continued development and uncertainties with next …pubs.awma.org/flip/em-nov-2017/emnov17.pdf ·...

The Magazine for Environmental Managers November 2017

Continued Development and Uncertainties withNEXT-GENERATIONAir Quality Sensors

October 20-22, 2015 • Houston, TX

AIR QUALITY MEASUREMENTMETHODS AND TECHNOLOGYNOVEMBER 7-9, 2017 • LONG BEACH, CA

Thank You Sponsorsand Exhibitors!

Silver

www.awma.org/measurements

Networking Breaks

For additional information about sponsorship and exhibition opportunities please contact Jeff Schurman, Business Development Manager, at [email protected]

Five Reasons to Sponsor or Exhibit:1. Raise your brand profile and generate new business2. Showcase your expertise and industry leadership3. Differentiate yourself from your competitors4. Protect and increase your market share5. Support your industry’s professional organization

Sponsorship PackagesFor Every Budget

Beginning at $250 - $500

Attention Exhibitors: Limited prime exhibit spaces are still available. Reserve your exhibit booth now!

GeneralOrsat Air Monitoring

2B Technologies, Inc. Aet�LabsAmbilabs

Consolidated Analytical SystemsENMET

Entech Instruments

Restek CorporationScion Instruments

Teledyne A�ITisch Environmental, Inc. TricornTech Corporation

TSI, Inc.URG Corporation

Yorke Engineering, LLC

Exhibitors

Global Analyzer SystemsLA Testing

��C Tec�GroupMagee Scientific

�ontrose �n�ironmental New Star Environmental, Inc.

Orsat

Sponsors

Gold

Be an ExhibitorBe a Sponsor

Table of Contents

em • The Magazine for Environmental Managers • A&WMA • November 2017

Columns

Etcetera: Solid Waste: What’s in a Name?by Anthony B. CavenderThe latest on the EPA’s ongoing project to define theterm “solid waste” in the context of regulating the recycling of hazardous secondary materials.

YP Perspective: Sensor Overload: LDEQ’s Mobile Air Monitoring Laboratoryby Nathan McBrideThe Louisiana Department of Environmental Quality’sMobile Air Monitoring Laboratory (MAML) is a fully-functional laboratory on wheels.

Departments

Message from the President: My Thanks for the Associationby Scott Freeburn

In Memoriam: Steve M. Hays

Last Stop: This Month in History (and other fun facts)

Continued Development and Uncertainties with Next-Generation Air Quality Sensorsby John Kinsman

A look at next-generation air quality sensors—typicallysmaller, more portable, and lower cost in contrast tomore expensive traditional monitoring equipment—increasingly being used for regulatory and research applications.

Characterizing AirQuality in a RapidlyChanging Worldby Kristen J. Benedict,Richard A. Wayland, and Gayle S.W. Hagler

Preparing for PersonalAir Sensors: State andLocal Air Quality Agencies on the Frontlines of CitizenScience by Jason Sloan, Sean Alteri, and Stuart Spencer

Evaluating Environ-mental Monitoring Applications of Low-Cost Sensors for Electric Utilitiesby Stephanie Shaw and Bruce Hensel

Low-Cost Sensor Pod Design Considerationsby Stephen Reece,Amanda Kaufman, Gayle Hagler, and Ronald Williams

Features

This is a good month to give thanks. For one, I give thanks to beable to sit in my comfy home listening to Mozart, Patsy Cline, andElise LeBlanc—a young Canadian artist I first heard at a strange motelhappy hour in the The Dalles, OR—while I write this. I also givethanks for the happy circumstances that have allowed life to unfoldas it has, resulting in the accumulation of so many good friendships,some lasting for decades.

Friends from my college football days and the Association have beenthe longest-term connections. I would not have predicted such anoutcome, but I am thankful for the result. As significant as my collegefriends have been to me and my family over the years, I want to talkabout the Association as an example of how connections built hereinhelp knit a career. Most folks well along in their careers understandhow these, sometimes casual, connections can become key turns offortune that have impacts beyond any expectation. For the youngprofessional reading this, consider it a case study in networking youcan’t replicate online.

I was introduced to A&WMA by my graduate school professor Dr. Richard W. Boubel, who was very active in the Association and wasone of the founders, I would say, of the Pacific Northwest InternationalSection (PNWIS). Dr. Boubel—Dick—went on to serve as A&WMAPresident from 1978 to 1979, and another grad student at the timewas future A&WMA President Joe Martone. While in grad school, Dickput my name forward for a new position created by the state agencyin Oregon, in response to a call he had received from Hal Patterson,then-state Air Director, hunting buddy, and A&WMA colleague.

During those years, there was much encouragement and support for professional development within the Oregon agency. This wasmanifested in support for obtaining one’s Professional Engineer (PE)registration, getting additional formal education, and joining professionalsocieties like A&WMA. I attended my first A&WMA meeting as avery young professional. I was given access to an annual meeting inPortland, OR, and directed visitors around the venue in exchange forbackrow seats in a few technical presentations. I was hooked.

I left the agency to work for Norm Edmisten, a former Public HealthService air specialist, and A&WMA member, who had been assignedto the U.S. Environmental Protection Agency’s (EPA) Oregon OperationsOffice before “retiring” to a consulting opportunity. In my new wet-behind-the-ears consulting role, I was encouraged to participate inorganizations such as A&WMA. I did and wound up making a few

presentations about interesting work; one of those was being on theteam that supported EPA in its only foray into actually running a stateair program. I found that if I practiced enough, I could give a technicalpresentation that was tolerable and as a result I sought out other opportunities. Attending a (usually A&WMA or PNWIS) conferencefor the purpose of presenting was the closest thing to a reward fordoing the often tedious work clients needed. In the consulting business,I found the professional exposure, through A&WMA, led to opportu-nities for both me and the companies for which I worked. This benefitstill exists and perhaps is easiest to see at our local Section andChapter meetings where people with problems are looking for solutions. (It’s hard to get this of type of connection with colleaguesand clients by looking for it on Craig’s List.)

When I began having employees working for me, I encouraged themat all opportunities to engage in the professional exposure offered bythe Association, often through PNWIS participation, but also throughspecialty conferences and the Annual Conference & Exhibition. Later,as an industry environmental engineer, and then compliance director,I maintained a close interest in and connection to the Association.When asked to run for a position on the Board of Directors, I washappy to, and more importantly, my company was willing to supportthat activity, even though other, narrower professional organizationsarguably provided more relevance to my daily work.

If this sounds like I was pursuing and encouraging professional expo-sure that was in part true, but from the very beginning my associationwith A&WMA and PNWIS has provided enjoyable, long-lasting social connections that weld the initial, perhaps tentative, professionalcontact. These social bonds are the connections that last through upsand downs and even complete career changes and give you supportand resiliency when change asks you to fold. Another thing aboutthe people you meet in this Association, they are engaged. These arevolunteers whose efforts make the Association or its Sections andChapters vital and relevant and are the type of folks that reach out, givethat extra effort, and whom you want on your team. I am thankful to know so many such members and to call them friends.

Like many other long-time members, I recognize the benefits thathave come from the Association and have looked for ways to giveback. When the Association (actually, good friend Sara Head) cameto me to ask me to be a candidate for President, I realized that if I really wanted to give back, there was no better time. I am thankfulfor that opportunity, too. em


by Scott A. Freeburn, P.E. » [email protected]

My Thanksfor the Association

Message from the President

A look at next-generation air quality sensors, which exhibit characteristics

such as being smaller, portable, and lower cost, in contrast to more expensive

traditional monitoring equipment, now used for regulatory and research

applications. This important topic previously has been the central theme of EM

issues in January 2014, August 2014, and November 2016.

Continued Development and Uncertainties withNEXT-GENERATIONAir Quality Sensors

Cover Story by John Kinsman




There are many potential applications for small, low-costsensors, including activities that do not necessarily requirethe highest quality data—such as community engagement,education, condition indicator, research, and management.1

On the other hand, next-generation sensors must deliver veryhigh-quality data if they are to support regulatory decisions,regulatory standard setting, and enforcement actions.

The quality of measurements by next-generation air sensorsis increasing but inconsistent, as affirmed in evaluations of thetechnologies by the U.S. Environmental Protection Agency(EPA; through its Citizen Science Toolbox; https://www.epa.gov/air-sensor-toolbox) and state groups (e.g., South Coast AirQuality Management District; http://www.aqmd.gov/aq-spec).

design of custom sensor “pods” collecting sensors into a singleunit to maximize ease of operation in community settings.

In the first article, Benedict et al. observe that the technologyaround lower cost air sensors is rapidly advancing as are thedeployments of these sensors around communities, leadingto proliferation of disaggregated, big data sets characterizinglocal air quality. The authors find that, with a growing diversityof air monitoring participants (e.g., citizens, communities, researchers, businesses) and associated data sets (e.g., sensor,satellite remote-sensing, traditional regulatory networks),there comes a need to make sense of it all. However, achievingsufficient quality data and a scientifically-grounded interpretation,especially as it relates to health, is a significant challenge.

In their 2016 EM article “Advanced Monitoring Technology:Opportunities and Challenges” (http://pubs.awma.org/flip/EM-Nov-2016/hindin.pdf) Hindin et al. discuss the “E-Enterprisefor the Environment” effort of EPA, state, and tribal agenciesto address the challenges and opportunities presented byrapidly changing monitoring technology. The authors statethat uncertainties about the quality of these devices and theinterpretation of the data they generate are limiting their impact.

In their 2014 EM article “Regulatory Considerations of LowerCost Air Pollution Sensor Data Performance” (http://pubs.awma.org/flip/EM-Aug-2014/judge.pdf) Robert Judge and RichardWayland observe that: “It is vitally important to understandthe quality of the data collected, because the consequencesof collecting poor quality data can be significant. … Becausethis data will be used to make decisions that may have far-reaching health and cost implications for the public or affected sources, EPA established data quality objectives forquality assurance and quality control (QA/QC) of air monitoringdata to ensure that the quality of the data supports using it tomake agency decisions.”

In this issue of EM, authors from the federal government (EPA),states (Association of Air Pollution Control Agencies; AAPCA),and an industry research organization (Electric Power ResearchInstitute; EPRI) discuss the uses, progress, and challenges ofnext-generation sensors. A companion article by Oak RidgeInstitute for Sciences and Education and EPA discusses the

Collecting and managing data are only a part of characterizingair quality. Complexities are numerous and include under-standing how sensor response may vary in environments thatdiffer from the testing environment, ensuring measurementsare accurate both initially and over time, having proper datathat describes a measurement, relating measurements tohealth effects or emissions standards, and communicating information in a consistent manner. EPA, the California AirResources Board, and the University of California, Davis AirQuality Research Center are planning an Air Sensor Interna-tional Conference in September 2018 to advance the scienceand engage all parties as measurement and information technologies evolve.

In the next article, Sloan et al. discuss how air agencies nowregularly field calls from the public concerning readings froma wide array of personal air sensors. Used properly, thesetools can allow students and citizens to explore their local environment, as well as learn about air quality and the U.S.Clean Air Act. As technology continues to improve, low-costair sensors may be able to augment regulatory networks ordetect pollution hotspots. The authors note that, as of June2017, two personal air sensors have been designated as a Federal Equivalent Method.

On the other hand, laboratory and field testing suggests thereare many low-cost sensors with quality that cannot compareto monitors used for regulatory purposes by air agencies. The

Next-generation sensors must deliver very

high-quality data if they are to support

regulatory decisions, regulatory standard

setting, and enforcement actions.

South Coast Air Quality Management District’s Air QualitySensor Evaluation Center (AQ-SPEC) has identified sensorsmeasuring particulate matter, carbon monoxide, ozone, andnitrogen oxides that display a complete lack of correlationcompared to regulatory monitors in field tests. Similarly, a NorthCarolina Department of Environmental Quality collocationstudy found a low-cost sulfur dioxide sensor showing levelsof more than 150 parts per billion (ppb) at the same locationwhere a regulatory monitor was reading less than 5 ppb.AAPCA has produced a fact sheet—“Preparing for PersonalAir Sensors: Definition, Opportunities, and Data Limitations”(http://www.csg.org/aapca_site/documents/AAPCAPersonalAirSensorFactSheet6-21-2017.pdf) —as a resource guide todefining personal air sensors, exploring opportunities for use,and recognizing data limitations.

In the third article, Shaw and Hensel note that sensor toolshave the potential to provide screening level data in currentlyunmonitored areas, or to supplement more complex existingmonitoring programs. EPRI scientists have brainstormed a variety of potential environmental (including those beyond airquality) applications relevant to electric utilities for which theywould like to see viable sensor options exist in the future.Some examples include use of sensors to help site permanentmonitoring instruments; measurement of emissions sourcesat power generation facilities (e.g., fugitive dust or methane);creation of early warning or detection systems; worker personalexposure monitoring; and interaction with local communitiesor other stakeholders for education. Despite a marked increasein recent reports summarizing results from field studies testingenvironmental sensors, a lack of evaluation data still exists formany potential applications.

Additionally, the fundamental designs of low-cost sensors makeit difficult to extrapolate performance from one site, metric, orsensor model to other situations, even if they are generallysimilar in design. Prior research studies have repeatedly shownthat while sensor components themselves can often havehigh precision, many of the detection techniques used canbe subject to chemical interferences (cross-sensitivities), drift,and other factors that affect data quality to a greater degreethan traditional instrumentation. Comprehensive site-specificperformance testing can be used to determine suitability ofsensors for electric utility applications. Several EPRI pilot projectshave already begun to test the capabilities of individual

environmental sensors, as well as logistics concerning theirusage, such as power supply (often off the grid) and wirelessdata transmission.

In the fourth article, Reece et al. consider key aspects of designing and developing deployable sensor pods, includingthe enclosure, ease-of-use features, power supply, data collectionand processing, and sensor selection. Understanding how thetechnology functions and then integrating the componentsinto a functional design requires technical expertise often notavailable at the citizen or community level.

In closing, there are a number of concerns that regulated entities and many regulators have regarding data quality associated with next-generation air quality sensors operatedindependently, which can be compounded when crowd-sourcing data or with clearinghouses featuring data collectedby different operators, using different sensor models, in different locations, and at different times. Justifying regulatoryand enforcement actions requires data collected under rigorousstandards. Regulators and regulated entities are concernedabout the resources that might be needed to address datasets, including those that may be shared on public websites,from next-generation air sensors.

Manufacturers, testers, and users of next-generation air sensorsshould continue to strive to improve the technologies by addressing data quality characteristics and considerations likethose discussed in previous EM articles by Dye et al. (“AirSensor Study Design—Details Matter”; http://pubs.awma.org/flip/EM-Nov-2016/dye.pdf and “Air Sensors: Quality Data forthe Right Application”; http://pubs.awma.org/flip/EM-Aug-2014/dye.pdf)—accuracy, precision, minimum detection limit,degradation of the instrument over time, reproducibility ofthe data, reliability, frequency of maintenance, data formattingand processing, interferences from other pollutants or frommeteorological conditions such as relative humidity or tem-perature, fouling, lack of ability by the user of some low-costsensors to be calibrated by the user, and limited airflow tothe sensor. Finally, an EPA advisory committee adds that“Metadata” describing the measurement conditions, time andlocation of sampling are needed to document the quality ofdatasets, since “When little is known about a data set, it cannot be used to make a decision, take a specific action, or be combined with other data sets.”2 em



John Kinsman is Senior Director of Environment with the Edison Electric Institute and Chair of EM’s Editorial Advisory Committee.E-mail: [email protected].

References1. Environmental Protection Belongs to the Public: A Vision for Citizen Science at EPA; EPA 219-R-16-001; National Advisory Council for Environmental Policy

and Technology, U.S. Environmental Protection Agency, December 2016, p. 5.2. Ibid. p. 33.

A discussion on projects collecting large volumes of unique air quality data

around the United States and how the collection of big data fits into the overall

picture of air quality management and characterization.

Characterizing Air Quality in a Rapidly Changing World

Characterizing Air Quality by Kristen Benedict, Richard Wayland, and Gayle Hagler



The technology around lower cost air sensors is rapidly advancing, as are the deployments of these sensors throughoutcommunities in the United States. As a result, disaggregated,big data sets characterizing local air quality are proliferating.These initiatives—often referred to as “Smart City” or “Internetof Things” (IoT)—are introducing entirely new sets of information.The U.S. Environmental Protection Agency (EPA), states, andtribes have been anticipating this development and publishedrecommendations for advancing the understanding, collection,and use of these data just one year ago.1 Recently, informationtechnology (IT) companies—and users of their products—haveemerged with technologies and tools that integrate air qualitydata into the larger IoT framework.

Collection of Big, Non-Traditional DatasetsAir quality data generated and collected by a variety of parties,including large IT companies, are growing at a rapid pace. ITcompanies are promoting the use of the cloud and advancedanalytics (e.g., machine learning) to characterize air qualityacross the globe. They are often driven by the desire to haveend users consume products (e.g., smartphone applications),provide data storage and access, or sell analytic services. Concurrently, a wide variety of private sector, academic, non-profit, and government entities are also developing new, integrated air quality sensor systems. These include wearables,urban sensor networks, mobile sensing systems, and applicationprogram interfaces. This presents a major shift in the UnitedStates, as government agencies have traditionally been themain resources for collecting, storing, sharing, and communi-cating air data. With a growing diversity of air monitoringparticipants (e.g., citizens, communities, researchers, businesses)

and associated data sets (e.g., sensor, satellite remote-sensing,traditional regulatory networks) there comes a need to makesense of it all.

EPA has funded numerous internal projects, external grants,and challenges to explore the development and applicationof new sensor technologies.2-8 Projects led by organizationsoutside of government are collecting data at an even largerscale. For example, Google street view vehicles repeatedlysampled street emissions in Oakland, California, creating thelargest urban air quality data set of its type.9 The WeatherCompany, which is owned by IBM, is collaborating with theinstrument manufacturer Purple Air to augment its existingpersonal weather station network with particulate mattersensors.10 The National Science Foundation is funding TheArray of Things (AoT) in Chicago, a network of interactive,modular sensor boxes installed to collect real-time data onthe city’s environment.11 The availability of very low-cost sensor equipment and supporting technical components ispromoting the development of these systems. However,achieving sufficient quality data and a scientifically-groundedinterpretation, especially as it relates to health, is a significantchallenge.

Air Quality Management and Characterization ConsiderationsCollecting and managing data are only a part of characterizingair quality. Complexities are numerous and include under-standing how sensor response may vary in environments thatdiffer from the testing environment, ensuring measurementsare accurate both initially and over time, having proper data

Go to www.awma.org/honors for descriptions and criteria.

Dedication definedA&WMA honors outstanding individuals and companies

in the environmental industry. Nominate someone today!

42nd Annual A&WMA Information Exchange December 12-13, 2017 • Marriott at Research Triangle Park • Durham, NC

Get the latest information on research and regulatory issues directly from the experts!

Join A&WMA at one of the best kept secrets in the industry for information exchange, networking, and solutions. This year's program will cover policy updates, regulatory changes, and research on the latest environmental topics.

Make your plans to attend now! www.awma.org/infoexchange



that describes a measurement, relating measurements tohealth effects or emissions standards, and communicating information in a consistent manner.

To date, the majority of efforts characterizing the performanceof air sensor technologies have been primarily conducted bycollocation of sensors with reference grade equipment in ambient, stationary environments without nearby pollutionsources.12,13 Long-term (i.e., more than 12 months) performanceof these sensors is generally poorly characterized, and somesensors have shown progressive drift with time.14 These areimportant considerations when assessing the quality of measurements and use of data analytic approaches. Theshort-term (i.e., days to months) performance characterizationor calibration developed at these locations may not holdwhen sensors are moved to near-source environments.

For example, particle counters using volume light scatteringtechniques can be influenced by particle size distribution,chemical composition, shape, and relative humidity. Any significant change from the initial calibration environment(e.g., a burst in large particles emitted by a nearby source)may result in measurement inaccuracies. Topography, varyingair pollution mixtures, and near-road measurements can alsointroduce uncertainty in virtual, network-based corrections.15,16

Additional research involving the collocation of sensors withreference-grade equipment near sources is needed, especiallyfor localized pollutants such as particulate matter, nitrogendioxide, carbon monoxide, and sulfur dioxide. Sensorsmounted on mobile platforms add additional complexity, asone must consider the representativeness of instantaneousmeasurements, as well as potential measurement artifacts introduced by mobile monitoring (e.g., vibration or pressureeffects). Metadata—data that describe the measurement andits data quality such as precision, bias, range, method detectionlimit, and calibration—are also critical in determining the enduse of air quality information.

In general, the science on air pollution and health doesn’t tell us what a few minutes of exposure to an elevated level of pollution will mean for an individual.17 While air qualitysensors currently have the capability to produce data on theorder of seconds to minutes, health research has been primarilyfocused on longer-term exposures to air pollution and the resulting health endpoints. Thus, a shorter-term sensor

measurement is not directly comparable to the National Ambient Air Quality Standards (NAAQS) or the related AirQuality Index (AQI) categories, which are based on a sub-stantial body of research supporting health-based standardsat longer averaging intervals (e.g., 24-hr PM2.5 standard, 8-hr max ozone standard).

As more high time resolution data become available, appro-priate context will be needed. AirNow is the current tool usedby EPA to promote real-time data exchange and protect public health. It uses quality assured data from long-term ambient monitoring networks to display and send air qualityalerts. AirNow presents data in a way that is consistent withthe NAAQS and published health evidence using official AQI colors (i.e., green, yellow, orange, red, purple, and maroon) to communicate information to the general public.

Meanwhile, a number of private sector groups have developeda variety of new air quality communication platforms, whichare using a myriad of approaches to communicate air qualityconditions. While there is a tremendous opportunity to learnfrom new and more localized datasets collected by thesegroups, creation of unique air quality communication platforms,visualizations, interpretations, use of the AQI or AQI colors indifferent ways, and alerts have the potential to confuse thepublic. Care needs to be taken to ensure air quality informa-tion is communicated with a scientifically-grounded approach.Further, understanding how people react to high-resolutiontemporal data is a subject of needed research.

E-Enterprise Advanced Monitoring Team UpdatesAs EPA monitors the rapid explosion of sensor networks, EPA,states, and tribes continue to make progress on advancedmonitoring priorities through the collaborative E-Enterpriseinitiative (see Table 1).18 Specifically discussed in this article areupdates on priority initiatives 1, 3, and 4 shown in Table 1.

Since one of the biggest concerns about sensors is the qualityof the data generated, EPA, states, and tribes are actively exploring the feasibility of an independent third-party certifi-cation program (Priority 1). The certification program conceptis unique in that it would be voluntary and based upon defensible data quality objectives for common non-regulatoryapplications, as well as other justifiable technology requirements

Table 1. E-Enterprise advanced monitoring priorities.

1 Options and Feasibility Analysis for an Independent Third-Party Certification Program

2 Technology Scan, Screen, and User Support Network

3 Data Interpretation

4 Data Exchange Standards

5 Lean the Current Technology Approval Process

!!!!!! Replace me with the correct header information !!!!!!



Kristen J. Benedict and Richard A. Wayland are both with the Office of Air and Radiation; and Gayle S.W. Hagler is with theOffice of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC.

References1. Hindin, D.; Grumbles, B.; Wyeth, G.; Benedict, K.; Watkins, T.; Aburn Jr., G.; Ulrich, M.; Lang, S.; Poole, K.; Dunn, A.D. Advanced Monitoring Technology:

Opportunities and Challenges. A Path Forward for EPA, States, and Tribes; EM, November 2016; http://pubs.awma.org/flip/EM-Nov-2016/hindin.pdf.2. Jiao, W.; Hagler, G.S.W.; Williams, R.W.; Sharpe, R.N.; Weinstock, L.; Rice, J. Field Assessment of the Village Green Project: An Autonomous Community

Air Quality Monitoring System; Environ. Sci. Technol. 2015; DOI: 10.1021/acs.est.5b01245.3. Jiao, W.; Hagler, G.S.W.; Williams, R.W.; Sharpe, R.; Brown, R.; Garver, D.; Judge, R.; Caudill, M.; Rickard, J.; Davis, M.; Weinstock, L.; Zimmer-Dauphinee,

S.; Buckley, K. Community Air Sensor Network (CAIRSENSE) project: evaluation of low-cost sensor performance in a suburban environment in the southeasternUnited States; Atmos. Meas. Tech. April 2016; https://doi.org/10.5194/amt-9-5281-2016.

4. Duvall, R.M.; Long, R.W.; Beaver, M.R.; Kronmiller, K.G.; Wheeler, M.L.; Szykman, J.J. Performance Evaluation and Community Application of Low-Cost Sensors for Ozone and Nitrogen Dioxide; Sensors 2016; DOI:10.3390/s16101698.

5. EPA Air Pollution Monitoring for Communities Grants. See https://www.epa.gov/air-research/air-pollution-monitoring-communities-grants.6. EPA’s Smart City Air Challenge. See https://developer.epa.gov/smart-city-air-challenge-resource-pages/.7. EPA Air Sensors Toolbox. See https://www.epa.gov/air-sensor-toolbox/air-sensor-toolbox-what-epa-doing#pane-1. 8. Wildland Fire Sensors Challenge. See https://www.challenge.gov/challenge/wildland-fire-sensors-challenge/.9. Apte, J.S.; Messier, K.P.; Gani, S.; Brauer, M.; Kirchstetter, T.W.; Lunden, M.M.; Marshall, J.D.; Portier, C.J.; Vermeulen, R.C.H.; Hamburg, S.P. High-Resolution

Air Pollution Mapping with Google Street View Cars: Exploiting Big Data; Environ. Sci. Technol. May 2017; DOI: 10.1021/acs.est.7b0089.10. The Weather Company Collaborates with PurpleAir to Provide Community Air Quality Data Across Its Consumer Properties. See http://www.theweather-

company.com/newsroom/2017/07/19/weather-company-collaborates-purpleair-provide-community-air-quality-data-across.11. Array of Things. See https://arrayofthings.github.io.12. Air Quality Sensor Performance Evaluation Center (AQ-SPEC). See http://www.aqmd.gov/aq-spec.13. EPA Office of Research and Development Evaluation of Emerging Air Pollution Sensor Performance. See https://www.epa.gov/air-sensor-toolbox/evaluation-

emerging-air-pollution-sensor-performance.14. Jiao, W.; Hagler, G.S.W.; Williams, R.W.; Sharpe, R.; Brown, R.; Garver, D.; Judge, R.; Caudill, M.; Rickard, J.; Davis, M.; Weinstock, L.; Zimmer-Dauphinee,

S.; Buckley, K. Community Air Sensor Network (CAIRSENSE) project: Evaluation of low-cost sensor performance in a suburban environment in the southeasternUnited States; Atmos. Meas. Tech. April 2016; https://doi.org/10.5194/amt-9-5281-2016.

15. Karner, A.A.; Eisinger, D.S.; Niemeier, D.A. and references therein, Near-Roadway Air Quality: Synthesizing the Findings from Real-World Data; Environ. Sci. Technol. June 2010; DOI: 10.1021/es100008x.

16. Baldauf, R.W.; Heist, D.; Isakov, V.; Perry, S.; Hagler, G.W.S; Kimbrough, S.; Shores, R.; Black, R.; Brixey, L. Air Quality Variability Near a Highway in ComplexUrban Environment; ScienceDirect January 2013; https://doi.org/10.1016/j.atmosenv.2012.09.054.

17. Keating, M.; Benedict, K.; Evans, R.; Jenkins, S,; Mannshardt, E.; Stone, S.L. Interpreting and Communicating Short-Term Air Sensor Data; EM November2016; http://pubs.awma.org/flip/EM-Nov-2016/keating.pdf.

18. Note: The progress on E-Enterprise advanced monitoring priorities described in this article is part of EPA’s broader effort to meet the opportunities and challenges posed by advanced monitoring technologies as described in an article in the November 2016 issue of EM. See “Advanced Monitoring Technology:Opportunities and Challenges” by Hindin et al.; http://pubs.awma.org/flip/EM-Nov-2016/hindin.pdf.

monitoring results. The team plans to recommend a set ofdata standards by the end of 2017. Concurrently, the teamcontinues to explore the development of metadata standards,as well as proposed data architecture.

ConclusionWith this rapid onset of new sensor technology and increasedavailability of new air quality data, it will be important for airquality professionals and data management companies towork together moving forward. Stakeholders in domestic andinternational governments, academia, commercial interests,and communities will need to collaborate to understand theunique characteristics of air quality measurements, how thedata relate to health effects and other factors, and the differentdata handling and analytic approaches that could be used to“improve” sensor measurements.

To promote engagement, EPA, the California Air ResourcesBoard (CARB), and the University of California, Davis Air QualityResearch Center are planning an Air Sensor InternationalConference (https://sehall4.wixsite.com/asic/home-landing) inSeptember 2018, which will focus on advancing the scienceand engaging communities. In order to harness the opportunityprovided by new data, it will be important to first understandand address some of the challenges. This is an ever changinglandscape and will require long-term strategic thinking fromall parties involved. em

supporting good data quality. The team has reached out tostandards organizations to determine the level of interest andpotential structure in supporting a long-term strategy andprogram. Recognizing that it may take several years to establishsuch a program, EPA is planning a workshop in spring 2018to discuss potential performance targets for air sensors usedin non-regulatory applications. The purpose of the workshopwill be a comprehensive review and analysis of informationrelated to determining performance targets and test methodsthat would support an eventual third-party certification programfor sensor technologies.

The Priority 3 data interpretation team has identified candidatepilot cities to test new and existing communication and visualization strategies for disparate datasets (e.g., air sensorand regulatory monitoring network data). Strategies for communicating data from pilot cities will explore providingshort-term measurements alongside the AQI; applyingweighted averages to hourly sensor measurements (i.e., theNowCast algorithm); presenting hourly values for one ormore pollutants; giving data additional context, including geographical and meteorological information; and providingappropriate data caveats such as marking data as “raw,” “provisional,” or “final.”

Consistent with the charge of evaluating existing data standards,the data exchange standards team (Priority 4) has completedan analysis and comparison of standards for continuous

With their on-the-ground experience, proximity to the public, expert personnel,

and ability to interpret current air quality information, state and local air agencies

are uniquely situated to help address technological and communication issues

surrounding the increased use of low-cost personal air sensors. The Association

of Air Pollution Control Agencies (AAPCA) has worked closely with its member

agencies, as well as the U.S. Environmental Protection Agency (EPA), over the

last two years to better understand these sensors and develop tools to help

facilitate proactive community engagement.

On the Frontlines of Citizen Science by Jason Sloan, Sean Alteri, and Stuart Spencer


Preparing for Personal Air Sensors:State and Local Air Quality Agencieson the Frontlines of Citizen Science

On the front lines. A number of recent developments underscore the public’s interest in personal air sensors andthe need for state and local air agencies to engage in theseissues. These include:

• EPA, through its Offices of Air Quality Planning and Standards and Research and Development, has providedpublic information in the form of the Air Sensor Toolboxfor Citizen Scientists, Researchers and Developers(https://www.epa.gov/air-sensor-toolbox) and Air SensorGuidebook (https://cfpub.epa.gov/si/si_public_file_down-load.cfm?p_download_id=519616), as well as throughchallenges and prizes like the Wildland Fire Sensors Challenge (https://www.challenge.gov/challenge/wildland-fire-sensors-challenge/) and Smart City Air Challenge(https://www.challenge.gov/challenge/smart-city-air-challenge/).

understanding and communication in the new world of personal air sensors. In 2016, AAPCA established a PersonalAir Sensor Workgroup, which includes active participationfrom association committees focused on public outreach andinformation, ambient monitoring, and local government. InSeptember 2016, the association held an extended topicalsession on personal air sensors during its Fall Business Meetingin Raleigh, NC. The session, Preparing for Personal Air Sensors:Communication, Context, and Perspectives, incorporated abroad spectrum of views from state and local air pollutioncontrol agencies, EPA, academics, and developers. Presenta-tions covered public outreach programs, collocation studies,sensor development, and potential future avenues for usingthis technology (Note: Presentations are available online;http://www.csg.org/aapca_site/events/2016FallBusinessMeetingPresentations.aspx.)

• Other EPA bodies, including the National Advisory Councilfor Environmental Policy and Technology (“EnvironmentalProtection Belongs to the Public: A Vision for Citizen Science at EPA”; https://www.epa.gov/sites/production/files/2016-12/documents/nacept_cs_report_final_508_0.pdf)) and E-Enterprise for the Environment (“AdvancedMonitoring Strategy and Implementation”; https://e-enter-prisefortheenvironment.net/our-projects/advanced-monitoring-projects/advanced-monitoring/)), have providedadvice on integrating personal air sensors into the work ofEPA and co-regulators.

• The U.S. Congress has expressed its interest in sensortechnology as well, with citizen science provisions of theAmerican Innovation and Competitiveness Act signed intolaw earlier this year and the introduction of H.R.1355, theCrowd Sourcing of Environmental Data Act of 2017(https://www.congress.gov/bill/115th-congress/house-bill/1355?q=%7B%22search%22%3A%5B%22air+monitor%22%5D%7D&r=4).

• State and local air agencies now regularly field calls fromthe public concerning readings from a wide array of personal air sensors.

AAPCA members have undertaken several initiatives to compare notes and develop strategies as they look to improve

Following the session and several in-depth workgroup discus-sions, AAPCA published a fact sheet, “Preparing for PersonalAir Sensors: Definition, Opportunities, and Data Limitations.”(http://www.csg.org/aapca_site/documents/AAPCAPersonalAirSensorFactSheet6-21-2017.pdf) Routinely updated, thefact sheet is a resource guide to defining personal air sensors,exploring opportunities for use, and recognizing data limitations.

Defining Personal Air SensorsDuring the topical session and early workgroup discussions,the difficulty in defining personal air sensors was identified asa key communications issue. While the term “low-cost sensor”applies broadly to technology used for highly localized meas-urements, participants stressed the need to better contextualizepersonal air sensors in terms of the ambient air monitoringperformed by air agencies.

The following consensus description was incorporated in theAAPCA fact sheet: “Low-cost and portable air sensors mayhave varying definitions. Personal air sensors may not meetthe stringent standards established for monitors operated bystate, local, or federal agencies and monitoring data used toinform compliance with National Ambient Air Quality Standards(NAAQS). An emerging technology, personal air sensors aresensing devices for air pollution that are designed to provide



Despite tremendous progress made in air pollution

control in recent decades, AAPCA’s April 2017

report noted disconnects between air quality

data and public perception.



short-term information regarding an individual’s immediateenvironment. Quality assurance and quality control measuresmay not exist for personal air sensors or their data, and theresult may be questionable data quality and a high variabilitybetween instruments.”

OpportunitiesMuch of AAPCA agencies’ work related to personal air sensorsfocuses on the opportunities presented by this type of citizenscience. Low-cost, portable personal air sensors can have useful classroom and citizen science applications. Used properly, these tools can allow students and citizens to exploretheir local environment as well as learn about air quality andthe Clean Air Act in the broader context of state, local, andnational air pollution control efforts. For example, these sensorscould be used in student-led research, efforts to engage communities in air quality awareness, or to help inform sitingof regulatory monitors. As technology continues to improve,low-cost air sensors may be able to augment regulatory networks or detect pollution hotspots.

Personal air sensors could help educate the public on airquality trends. In August 2017, EPA released its air trends report, “Our Nations’ Air: Status and Trends Through 2016,”(https://gispub.epa.gov/air/trendsreport/2016/) highlightingtrends also included in AAPCA’s April 2017 report, “TheGreatest Story Seldom Told: Profiles and Success Stories inAir Pollution Control” (http://www.csg.org/aapca_site/documents/GreatestStory4-17-17.pdf). Both reports demonstrate the

tremendous progress made in the United States in virtuallyevery measure of air pollution control over the last severaldecades, and rely on high-quality monitoring data from local,state, and federal environmental agencies.

Despite this progress, public opinion polls suggest that theseimprovements have gone under the radar for most Americans.The introduction to AAPCA’s April 2017 report explored fivekey disconnects between air quality data and public perception,which present opportunities for expert air agencies. For example, between 2000 and present, between one-third andone-half of Americans polled annually by Gallup said theyworry a great deal about pollution.1 Over that same period,aggregate emissions from six common pollutants fell by morethan 60 percent, air releases of toxic chemicals dropped morethan half, and the carbon intensity of the economy wentdown by more than 25 percent. Greater public engagementcould facilitate citizen understanding of air quality, and helpfocus energy and resources on the most pressing environ-mental issues.

Inquiries about personal air sensors, and increased publicawareness as a result of these technologies, offer an openingfor air agencies to provide important information to their constituents about monitoring technology, the Air QualityIndex, and the basis for standards under the Clean Air Act.These agencies need to be able to move beyond technicaldescriptions of “parts per billion” or “micrograms per cubicmeter,” and create the capability to highlight case studies,

Scholarships A&WMA has scholarships available for air quality research, solid and hazardous waste research, waste management research and study, and air pollution control and waste minimization research. Last year the Association headquarters awarded $ ,000 in scholarships.

Thesis and Dissertation AwardsA&WMA acknowledges up to two exceptional Masters Thesis and up to two exceptional Doctoral Dissertations each year. Nominations shall be made by the student's faculty advisors, who are members of A&WMA, only.

Best Student Platform Paper AwardThe Platform Paper Award will acknowledge up to two exceptional technical papers at the M.S. and Ph.D. academic levels for papers submitted for presentation at the 201 A&WMA Annual Conference & Exhibition on June

Best Student Poster AwardThe Student Poster Awards recognize student posters to be the best amongst those considered in the undergraduate, masters, and doctoral categories. Student must present the poster during the 201 A&WMA Annual Conference & Exhibition on J

to be eligible for this competition.

Each year, the Air & Waste Management Association (A&WMA) recognizes outstanding students who are pursuing courses of study and research leading to careers in air quality, waste management/policy/law, sustainability. Award opportunities include:

A&WMA Student Opportunities

Visit www.awma.org/scholarships for more information.



community involvement, and localized benefits. A 2004study by Brody et al. examining local patterns of air qualityperception in Texas, found that public views are not drivenby actual air quality conditions but that “other factors such asa sense of place, neighborhood setting, source of pollution,and socioeconomic characteristics appear to shape perceptions.”2

The researchers suggest that “[p]olicymakers thus cannot relyon scientific data alone to drive a public decision-makingprocess, but also must consider location-based factors, thespecific make-up of the population, and the venues throughwhich this population receives information on environmentalconditions.”

LimitationsThe ability of air agencies to provide context to the public isparticularly important in light of differing quality of air sensorscurrently available in the United States. Section 103 of theClean Air Act directs EPA to “conduct a program of research,testing, and development of methods for sampling, measure-ment, monitoring, analysis, and modeling of air pollutants.” In accordance with 40 CFR 53, EPA establishes “referencemethods” or “equivalent methods” for criteria pollutants, stating that “each method is acceptable for use in state orlocal air quality surveillance systems.” As of June 2017, twopersonal air sensors (the Personal Ozone Monitor and theModel 405 nm NO2/NO/NOx Monitor) have been desig-nated as a Federal Equivalent Method (FEM), though a userwould need to ensure that the instrument is used accordingto FEM protocol.3

On the other hand, laboratory and field testing suggeststhere are many low-cost sensors with quality that cannotcompare to monitors used for regulatory purposes by airagencies. The South Coast Air Quality Management District’sAir Quality Sensor Performance Evaluation Center (http://

www.aqmd.gov/aq-spec/evaluations/summary), which “aimsat being the testing center for low-cost air monitoring sensorsto establish performance standards by which sensors areevaluated,” has identified sensors measuring particulate matter,carbon monoxide, ozone, and nitrogen oxides that display acomplete lack of correlation compared to regulatory monitorsin field tests. Similarly, a North Carolina Department of Envi-ronmental Quality collocation study (http://www.csg.org/aapca_site/events/documents/Cherry-MonitoringSO2UsingSensorTechnology-9-21-2016.pdf) found a low-cost sulfurdioxide sensor showing levels of more than 150 parts per billion (ppb) at the same location where a regulatory monitorwas reading less than 5 ppb.

In order to capture the differing quality of sensors, AAPCA’sfact sheet lays out a number of potential limitations to dataderived from personal air sensors. These include:

• Personal air sensors may not have established quality controland quality assurance measures and may not conform toquality assurance documents established by EPA or otherregulatory bodies.

• Personal air sensors may have questionable data quality,and provide data that might not correlate with Federal Reference Method (FRM) or Federal Equivalent Method(FEM) monitors used for regulatory purposes.

• Personal air sensors may display air quality information differently than those data used by air agencies, includingaveraging time, units of measure, level, exposure, andmethod.

• While short-term measurements from personal air sensorsmight be for a second or minute, it is difficult to relate thisdata to the science of health effects of air pollution, whereeffects are evaluated based on an average of an hour orday of exposure.

In Memoriam: Steve M. Hays

A&WMA member Steve M.Hays, P.E., CIH, FACEC, FAIHA,founding partner and chairmanemeritus of Gobbell Hays Partners(GHP) Environmental + Architecturefirm, died in Nashville, TN, onSeptember 28, 2017, after an extended illness.

An A&WMA member since 1991, Hays was a nationalleader in identifying and safely mitigating hazards related toasbestos, mold, and lead-based paints in buildings for morethan 30 years, and was the co-author of two books: IndoorAir Quality: Solutions and Strategies and Settled Asbestos Dust Sampling and Analysis.

Appointed to the Board of the National Institute of BuildingSciences by President Bill Clinton, he was a Fellow of theAmerican Industrial Hygienists Association and the AmericanCouncil of Engineering Companies. Among his many honorswere the Mortimer M. Marshall Lifetime Achievement Awardfrom the National Institute of Building Sciences (2013) andthe Donald E. Cummings Memorial Award from the AmericanInstitute of Industrial Hygiene (2017).

Hays taught at Georgia Tech Research Institute and The Environmental Institute in Georgia and was a frequent guestlecturer at the University of California, Berkeley and Texas A & M University.



• Personal air sensors may not be operated in ambient conditions or by siting requirements in accordance withTitle 40, Part 58 of the Code of Federal Regulations (CFR),Appendix E.

• Personal air sensors may have diminished accuracy fromhumidity, temperature, transitioning from indoors to out-doors (or vice versa), as well as cross sensitivities to othergases.

• Personal air sensors may not have the geographical infor-mation and documentation that are necessary to ensureconsistent and comparable data.

• Personal air sensors need regular calibration and may besubject to drift and decreased sensitivity over time.

• Personal air sensors may have a high variability betweeninstruments.

Air Agencies on the FrontlinesIn a world of social media, the advancement of big data, andhighly localized measurement technologies, it is more importantthan ever for state and local air agencies to develop proactive,credible avenues to communicate with the public about airquality. AAPCA and its members stand ready to help providecritical context, encourage educational opportunities, and recognize data limitations in a world of proliferating sensingtechnology. em

Jason Sloan is Policy and Membership Associate at Association of Air Pollution Control Agencies (AAPCA). Sean Alteri is Directorat Kentucky Division for Air Quality and 2017 AAPCA President. Stuart Spencer, is Associate Director at Arkansas Department of Environmental Quality and 2018 AAPCA President.

The Association of Air Pollution Control AgenciesThe Association of Air Pollution Control Agencies (AAPCA) is a national, non-profit, consensus-driven organization focused on assistingstate and local air quality agencies and personnel with implementation and technical issues associated with the U.S. Clean Air Act.AAPCA represents more than 40 state and local air agencies, and senior officials from 20 state environmental agencies currently siton the AAPCA Board of Directors. AAPCA is housed in Lexington, Kentucky as an affiliate of The Council of State Governments.

References1. Gallup Inc. “Environment,” March 2017; available at http://www.gallup.com/poll/1615/environment.aspx.2. Brody, S.D.; Peck, B.M.; Highfield, W.E. Examining Localized Patterns of Air Quality Perception in Texas: A Spatial and Statistical Analysis; Risk Analysis

2004, 24 (6), 1561-1574; available at http://research.arch.tamu.edu/media/cms_page_media/3391/RiskAnalysis_airq.pdf.3. List of Designated Reference and Equivalent Methods; U.S. Environmental Protection Agency, June 16, 2017; available at https://www3.epa.gov/ttn/amtic/

files/ambient/criteria/AMTIC_List_June _2017_update_6-19-2017.pdf

Get the latest information and solutions on the implementation of the Appendix W promulgation and other issues related to the Guideline on Air Quality Models.

The Keynote Session includes presentations on the work EPA is doing in the areas of regulatory policy, Appendix W, AERMOD, cumulative impact analyses, single source ozone and PM2.5 demonstrations, and more.

The popular Town Hall Meeting will feature environmental experts from EPA, Georgia EPD, U.S. Forest Service, and law �rms discussing successes and challenges with the Guideline revision.

Technical Sessions will consist of over 40 presentations from experts around the world covering: • AERMOD Issues and Applications • Meteorological Issues • Aerodynamic Downwash • Secondary Formation Modeling

Courses on Monday, November 13 will help you gain a working knowledge of the most popular models used in the industry: • AERMOD • CAMX • SCICHEM 3.1

Thanks to our sponsors:

Guideline on Air Quality Models: THE CHANGESNovember 14-16, 2017 Chapel Hill, North Carolina

Since the 1960s, TRC has served clients with air quality systems design, permitting, dispersion modeling, licensing, regulatory compliance, engineering, auditing, due diligence review, litigation support, and expert witness services. As one of the nation’s largest air measurement �rms, TRC also provides emission testing, ambient monitoring, and meteorological monitoring services.

Lakes Environmental is internationally recognized for its technologically advanced environmental modeling software and data products that increase productivity, reduce errors, and provide unique solutions in an ever-increasing regulatory constrained world.

With over 4.5 million customers and approximately 44,000 megawatts of generating capacity, Atlanta-based Southern Company is the premier energy company serving the Southeast through its subsidiaries.

Register and �nd details online at www.awma.org/aqmodels.

Gold

Silver

General

A look at the potential applications for new low-cost sensors in industrial

environmental monitoring.

Evaluating Environmental Monitoring Applications of Low-Cost Sensors for

Electric Utilities

Evaluating Low-Cost Sensors for Electric Utilities by Stephanie Shaw and Bruce Hensel


A variety of novel environmental monitoring technologies,such as small low-cost air quality sensors, have been on therise for the past several years, fueled in part by advances inmanufacturing technologies that have eased miniaturizationof electronics. These devices are often quite inexpensive andaccessible to potential users, while still providing real-time information on environmental metrics. Sensor tools have thepotential to provide screening-level data in currently unmoni-tored areas, or to supplement more complex existing moni-toring programs. However, their applicability for environmentalmonitoring performed by electrical utilities has yet to be vetted. This article considers potential applications of sensorsto a subset of industrial facility monitoring that is occurring at electric utility sites.

Potential for Sensors in Industrial Environmental MonitoringScientists and engineers at our organization, the ElectricPower Research Institute (EPRI), are always looking for newtools and processes that may help electric utilities operate theirfacilities more efficiently, with more flexibility, and at lowercost. Over the past several years, EPRI has engaged in a cross-disciplinary research program on intelligent sensor systemsand associated data analytics that is investigating sensor performance and data acquisition, data communications andmanipulations, and final use of sensor data in facility opera-tions (see Figure 1). Sensor applications are considered withrelevance to the various electricity research sectors: generation,



nuclear power, transmission and distribution, and energy and environment.

Intelligent sensors are needed throughout the power systemto transform raw data into actionable information. For example,EPRI has developed its own sensor packages for equipmentmonitoring and condition-based maintenance. These devicesare being tested on the transmission grid and at substationsto demonstrate the technology’s potential to reduce or extendintervals between preventive maintenance and surveillancetasks. Development and in-plant testing has been conductedof novel systems that can continually sense torsional vibrationat turbine shafts. This enables early detection of conditionsthat cause turbine blades and other rotor elements to fail.

Similarly, chemical or physical sensors might be relevant toolsfor environmental monitoring at power system facilities. Inaddition to their relatively low cost, the ability to deploy sensorsystems in complex environments and without line powermake them attractive for locations that cannot accommodatetraditional instruments due to space or infrastructure limitations,such as on the grounds of working industrial facilities. Ideally,real-time information about electric power system assets provided by sensors would be secure, and incorporated tooperate the system efficiently and effectively while managingenvironmental impacts.

EPRI scientists have brainstormed a variety of potential

Figure 1. EPRI’s approach to electric utility sensor systems.



environmental applications relevant to electric utilities for whichthey would like to see viable sensor options exist. Some examples include:

1. Use of sensors to help site permanent monitoring instruments;

2. Measurement of emissions sources at power generationfacilities (e.g., fugitive dust or methane);

3. Creation of early warning or detection systems, such asfor geotechnical parameters (e.g., berm stability) orleaks of materials in confined spaces;

4. Worker personal exposure monitoring; and5. Interaction with local communities or other stakeholders

for education.

Listing of these example applications does not necessarilymean that the technologies are currently commercially availableand appropriate for deployment now, rather they are aspira-tional applications if sensors of appropriate performance are identified.

Real-World Testing Is Vital for Sensor EvaluationAs with any new and emerging technology, it is crucial to ensure that the performance capabilities and limitations ofsensors are adequately understood before they are applied.These complexities can then be communicated to stakehold-ers. Despite a marked increase in recent reports summarizingresults from field studies testing environmental sensors, a lackof evaluation data still exists for many potential applications.Additionally, the fundamental designs of low-cost sensorsmake it difficult to extrapolate performance from one site,metric or sensor model to other situations, even if they aregenerally similar in design.

Prior research studies have repeatedly shown that while sensor components themselves can often have high precision,many of the detection techniques used can be subject tochemical interferences (cross-sensitivities), drift, and other factors that affect data quality to a greater degree than traditional instrumentation. Even if these concerns may beanticipated due to manufacturers’ specifications and prior laboratory analysis, they do not always present in expectedways due to the complex real-world ambient air matrix inwhich they are deployed. Therefore, comprehensive site-specific performance testing can be used to determine suitability of sensors for electric utility applications.

A further need in the design of sensor performance testing is a robust assessment of the full sensor system cost. For example, the capital cost for the sensor component and thepackage into which the sensor is incorporated, including electronic control boards, power systems, wireless communi-cation systems, and data handling infrastructure, all need

careful evaluation. Additionally, operations and maintenancecosts for sensor deployments are often expected to be relativelylow, due to the relative ease-of-use of sensors compared totraditional reference instrumentation. However, the labor costof any need for frequent maintenance (e.g., online or offlinecalibrations or cleaning activities) should be a consideration.

Management of the challenging “big data” files resulting fromthe real-time measurements can also be substantial. Any evaluation of whether low-cost sensor technologies are an appropriate opportunity to pursue for a given applicationshould, at minimum, consider these issues that contribute to their classification as a help or a hindrance to facility monitoring.

Lessons Learned from Test ApplicationsSeveral EPRI pilot projects have begun to test the capabilities ofindividual environmental sensors, as well as logistics concerningtheir usage, such as power supply (often off the grid) andwireless data transmission. One pilot project involved a deployment of particulate matter sensors for fugitive dustmeasurement at a power generation facility. Dust sources at these facilities can include material handling processes forcoal and ash, which can include bulldozing, rail delivery, and wind-driven lofting and advection. Road dust can also be present.

Three sensor systems from different manufacturers weretested to see if they could detect dust plumes. All systems incorporated sensors using optical techniques to count particlenumber, with conversions required to produce results inunits of particle mass. Two of the systems were powered withsmall solar panels and batteries, rather than through connectionto grid power (see Figure 2). The sensor results will be com-pared against reference instruments, including hourly FederalEquivalent Method data, sub-hourly data, and particle sizedistribution data.

This deployment was only recently completed, and analysis isongoing, but early results suggest that some of the deployedsensors did capture many of the dust plumes of interest.Good precision was observed between duplicate sensors ofthe same manufacturer and model (see Figure 3). Accuracy is still to be determined. As the field study lasted for ninemonths, an initial consideration of the sensor lifespan and long-term replacement frequency is possible. Impacts of seasonalmeteorology on sensor performance will also be investigated.

EPRI is also testing sensors in a groundwater monitoring deployment using down-hole multi-sound sensors equippedwith probes for pH, electrical conductance, chloride, tempera-ture, and groundwater elevation. There is currently no sensorthat can completely replace a traditional groundwater monitoring program, particularly for inorganic applications,



because probes are not commercially available for constituentssuch as boron and sulfate dissolved in groundwater. However,there may be applications where sensor information can supplement traditional monitoring using surrogate constituentssuch as electrical conductance and chloride. For example,providing higher time resolution information between samplingevents may be of value in groundwater environments withrapid flow, such as karstic groundwater systems.

Another potential use is monitoring of indicator constituentsduring remediation. For example, one use could be to optimizeoperation of an enhanced groundwater flushing system, whereclean groundwater is injected at some wells and impactedgroundwater is extracted at other wells, and where injectionand pumping rates can be modified in response to systemeffectiveness as indicated by the sensor array.1 Results ofEPRI testing to date have demonstrated the ability of theseinstruments to achieve the objective of monitoring short-termfluctuations in groundwater quality. The results have also suggested that maintenance requirements for these devices,in their current stage of development, makes them bestsuited to specialized applications.

Other innovative environmental sensor applications have also been tested. One utility member of EPRI has set up anextensive array of geotechnical sensors that provide real-timedata to monitor dike stability at impoundments using vibratingwire transducers to monitor pore water pressure, inclinometersto measure lateral movement, and borehole extensometer tomonitor settlement/vertical movement. EPRI is documentingthis successful application so that other companies can consider similar deployments.2

Both expected and unexpected challenges were encounteredduring these pilot deployments. For example, complicationswith the air particulate matter sensors were expected at highrelative humidity levels, and were indeed observed. However,prior deployments and manufacturer specifications did notprovide prior indication of the number of large false positivesignals that were observed at temperatures below zero degrees Celsius. Additionally, an unexpected failure of electromagnetic compatibility was found during a deploymentat a power generation facility, which was associated with asingle component in a sensor system package. This samepackage design was deployed at a variety of other types ofsites (e.g., rural, urban) with no indication of any issue.

A substantial upfront labor investment was required for thepilot deployments to understand drivers of sensor performanceand to determine likely maintenance needs. These labor costscould likely be reduced with future deployments, when asensor network is beyond the pilot stage. In addition to upfrontlabor, resources are needed on an ongoing basis to checksensor readings for evidence of drift or malfunction, and to

make necessary adjustments in the field. This requires train-ing of individuals to understand how to calibrate sensors andotherwise maintain the equipment.

Important Study Design FeaturesBest practices for study design and implementation learnedfrom the EPRI deployments are evolving. Most practices rele-vant at utility sites were like those previously recommendedfor ambient sites. For example, it was important to test multiplesensor devices of same manufacturer and model, as well asmultiple different models. This helped to detect and address

Figure 2. Example of an air sensor node on a tripodstand, with solar panel and battery for power provision.



Stephanie Shaw and Bruce Hensel are Principal Technical Leaders at the Electric Power Research Institute in Palo Alto, CA.

References1. Corrective Action Technology Profile: Groundwater Extraction and Treatment at Coal Combustion Residual Facilities; Technical Report 3002010945; EPRI, Palo

Alto, CA: 2017.2. SENTINEL: Geotechnical Instrumentation Overview—Example Application and Cost. EPRI, Palo Alto, CA: in-press.3. Dye, T.; Graham, A.; Hafner, H. Air Sensor Study Design—Details Matter; EM November 2016.http://pubs.awma.org/flip/EM-Nov-2016/dye.pdf

the same, slow-flowing, mass of groundwater. Therefore,chemical measurements are not independent and are notuseful, which makes moot one of the advantages of usingsensors, which is collecting many readings over a short period. This suite of details to consider during sensor deployments highlights the importance of incorporating a site-specific approach to project design.

Another important component of any eventual sensor monitoring program determined to be suitable for real-worlduse at utilities is an alerting system. For such an application,data are accumulated, statistically evaluated or compared tometrics, and alerts sent when readings are out-of-bounds ofexpected values. Alerting facilitates the ability to take operationalaction to respond to the observations.

Future ValueAll signs point to a continuation of research on environmentalsensor applications and performance evaluations. EPRI willalso continue to review new sensor developments and potentialapplications for opportunities and partnerships that may berelevant to electric utilities. These include applications relevantto ambient environments and traditional environmental monitoring networks, as well as facility monitoring. EPRI’sfocus is on technologies that provide high data quality whilehelping electric utilities to lower their monitoring costs, provideincreased spatial or temporal density of measurements, orotherwise provide new insights to assist with managing facility operations. em

Figure 3. Example field measurements in particles per cc of air for duplicate sensor systems of the same manufacturerand model (x- and y-axes) for (a) PM1, (b) PM2.5, and (c) PM10 size fractions.

issues with sensor stability, precision, and usefulness thatwould adversely affect results. Advance review of the technologyspecifications and laboratory testing cannot replace testingthe devices of interest at the site of interest. It is crucial to include a collocated certified monitor (e.g., Federal Referenceor Equivalent Method) or similarly vetted sampling andanalysis protocols, as the best reference for comparison tosensor performance. This will help ensure accurate sensorreadings and provide early indications of drift, confounding,or other issues. The reference instrument that provides data on a similar time interval as the sensor (i.e., typically lessthan 1 hour for air) enables the most robust comparison.

Development of relevant data quality control and quality assurance approaches for long-term sensor operations anddata management is also important. Ongoing intermittentcomparison of sensor data against data from more traditionalmethods can be done on time periods suitable for the equip-ment and metrics being measured. Other details importantto consider, from the perspective of an air sensor deployment,are summarized in a prior issue of EM.3

For groundwater, another important consideration is whetherthe cost of installing and maintaining the sensor is lower thanthe cost of sending a person to collect and a laboratory to analyze the samples. Another consideration for groundwaterapplications is sample independence. In many non-karsticgroundwater environments, multiple sampling events on thesame day, or even same week, are essentially drawing from

A look at the decision-making process used in the development of two unique

low-cost air quality sensor pods.

Low-Cost Sensor PodDesign Considerations

Low-Cost Sensor Pod Design Considerations by Stephen Reece et al.


by Stephen Reece, Amanda Kaufman, Gayle Hagler, and Ronald Williams



to ensure adequate data collection to meet a specific purpose.This article describes some of the decision-making used inthe development of two unique low-cost sensor pods as ameans to share our generalized approach with users havingsome degree of technical expertise. Each example was designedto meet the specific needs of a unique user community, andtherefore, the two had quite dissimilar requirements.

Key Parameters of Pod DevelopmentVarious decisions must be made during the design and development of a deployable sensor pod. These decisionsmust consider the technical abilities of the user, the length ofthe deployment, and the measurement goals of the deployment.The primary design decisions include:

1. Pod Enclosure and Ancillary Components2. Ease of Use Features3. Power Supply4. Data Collection and Processing5. Sensor Selection

Pod Enclosure and Ancillary ComponentsThe design and level of sophistication of a sensor pod is influenced by the intended use in exploring environmentalchallenges. Regardless of application, all sensor pods reflectcompromises among a number of competing factors affectingfunctionality. Materials for enclosures may range from metallic to plastic, and pods may be custom-built or use a commercially available enclosure.

A benefit of metallic enclosures is the flexibility to customizeon the fly via drilling holes, cutting openings, and so forth.However, these cases are often heavier, can have inadvertentsharp edges, and may require special equipment to makemodifications.

Plastic can be a less expensive alternative for enclosures and the rise of three-dimensional printing supports rapid prototyping and iteration of a custom case. A risk with plasticmaterials is potential interference; great effort should bemade to ensure the material is inert and is non-reactive with the target pollutant.

A lightweight material is ideal for versatile and portable sensorpods. Such designs would allow for mobile measurements,where the sensor pod is being worn or carried by the user.To ensure the sensor pod is durable, internal componentsshould be packaged in a weather-resistant, rugged enclosureto protect them from damage during transport and minimizeinterferences from environmental conditions. Depending on the performance specifications of the internal sensors, environmental conditions, such as sunlight, precipitation,relative humidity (RH), and temperature can influence response.7-10

Teach a course at ACE 2018! Share your expertise and enhance the knowledge

of others in the industry.

A&WMA is looking for courses on timely environmental topics including, but not limited to:

• Air Pollution Controls • Modeling and Monitoring • Environmental Management • Air and Waste Regulatory Compliance Permitting • Emissions Sampling and Analysis • Multi Media Auditing • Regulatory Law • QEP Preparation, and more.

If you are interested in teaching a course on June 24 or 25, 2018, please go to www.awma.org/courses and complete the Course Proposal Form. Deadline is December 14, 2017.

Public concern about air quality is growing in communitiesaround the globe, as citizens learn more about the potentialhealth effects of the air they breathe.1 In the United States, airquality monitoring has often been restricted to organizationsadministering Federal Reference Method (FRM) or FederalEquivalent Method (FEM) equipment or other professional/academic institutions operating research-grade instrumentation.2

The recent development of low-cost (< $2,500) air qualitysensors has generated opportunities for communities to engage in citizen science to address air quality concerns on alocal level, but many of these low-cost sensors have not beenfully evaluated and may have undefined issues regardingperformance characteristics and data quality.3-5

In an effort to gain perspective on sensor performance andsupport a wide range of interested stakeholders, the U.S. Environmental Protection Agency (EPA) has developed anddeployed a variety of custom sensor pods in community settings to evaluate their performance under real-world conditions. These sensor pods were constructed by combiningvarious low-cost original equipment manufacturer (OEM)component sensors and system integration technologies intoa single unit in an effort to maximize ease of operation, whilemeeting a specific research requirement.3,6 Many of the sensorcomponents selected for these pods were chosen based uponresearch findings from direct reference monitoring comparisons.This approach provides the ability to leverage knowledgegained regarding sensor operational requirements and generalperformance capabilities with application needs.

Researchers at the EPA are often asked about how they developsensor pods. Development is guided by project requirements



To ensure that sensor pods are operated under proper conditions and measured values are representative of ambientconcentrations, additional components, such as fans, activesampling inlets, temperature sensors, RH sensors, and non-reactive samplings lines, are factors we consider in the designof sensor pods. Appropriately positioned inlets and environ-mental sensors (e.g., temperature and RH) help ensure morerepresentative sampling. Inadequate planning and testing ofthe design of a sensor pod can result in a device that producesresults not reflective of true environmental conditions.

Ease of Use FeaturesEase of use is a critical factor supporting successful operationof sensors pods by community members, who may have adiversity of backgrounds and level of comfort with new tech-nology. User-friendly features help minimize the risk of user

projects and should be considered when incorporating user-friendly features.

Power SupplyUnlike traditional regulatory monitors, a sensor pod’s low-costinternal components typically have low energy requirements(< 30 watts). This often allows sensor pod energy supply decisions to be a function of the location and duration of deployment. A sensor pod can be operated using variouscombinations of AC, solar, and battery power.

Sensor pods using AC power are more suitable for urbansettings, where the electrical grid can supply AC power. Thereliability of electrical grids varies by location, so sensor podscan also be equipped with an internal battery as a backup toprotect against the event of a power failure. This allows for

error and the amount of time required for training. Theamount of operation time required to deploy a sensor podand start data collection will often be dictated by the amountof tasks that are not automated via firmware. Firmware provides the instructions needed for the microprocessor tocommunicate with sensors and initialize required tasks.

A fully automated sensor pod can be designed to have apower switch to simultaneously power all components and,via an onboard programmed microprocessor, initialize sensors,perform self-checks, set timestamps, and begin logging data.Scripts can also be incorporated to provide quality assuranceby performing checks and balances to alert users to a rangeof issues, such as low battery warnings, fluctuations inflowrates, sensor failure, and interruptions in data logging.Quality assurance scripts can direct a sensor pod to terminateoperations to prevent further damage in the event of a failure.

Real-time data and alerts can be displayed on an interactivegraphical user interface on a touchscreen or an external laptopto allow users to navigate through menus and configurationsto monitor the status. This provides a visual method to clearlyidentify which components are operating and to communicatethe cause of any potential issue. The complexity of sensorpod design and the experience of the user will vary across

continuous measurements during momentary power outagesand provides time to follow proper shutdown procedures ifthe primary power source is down for an extended period.

Solar-powered sensor pods are designed for outdoor deploy-ments, where ideal conditions permit. However, a sensor poddependent on solar panels as a main power source is at riskof failure during non-ideal weather conditions. Sensor podsthat rely on solar panels must also be equipped with an internalbattery and controller, which supports the ongoing charge/discharge of the battery and automatic shutdown of the podto protect the battery under critical low-charge conditions.

Sensor pods powered only by battery are typically used fordeployments with short durations or in rural areas that lackaccess to electrical connections. In these situations, additionalbatteries for periodic battery changes are required to maximizedata collection, otherwise measurements will be interruptedfor allocated recharge time.

A wide variety of batteries are available (e.g., lead acid, lithiumion, lithium polymer) with different advantages depending onapplication type. These trade-offs include, but are not limitedto: safety, ease of use, and weight considerations. To determinethe battery capacity or number of solar cells requires an

Inadequate planning and testing of the

design of a sensor pod can result in a

device that produces results not reflective

of true environmental conditions.

!!!!!! Replace me with the correct header information !!!!!!



energy budget to be performed to calculate the required operational watts of the internal components. The frequencyat which batteries are exchanged will also influence the required capacity of the power source. The battery can bestored in a dedicated enclosure or the sensor pod can be designed to accommodate an internal battery bay. In eithercase, the internal battery should be easily accessible to accommodate routine battery recharge and/or replacementin a safe manner and to reduce the amount of time the sensor pod is offline.

All sensor pod designs should be reviewed by a qualified engineering team to ensure all integrated electrical circuitsmeet required standards of safety. Power requirement considerations are essential in ensuring proper operation of sensor pod components and maximizing performance.

Data Collection and ProcessingSensor pods are composed of a range of components that eachrequire independent power and communication connections.To provide power and communication to these devices requires a simple computer (microprocessor) capable of: (a) collecting raw data and controlling major operations, (b) locally processing raw data to final reporting units ortransmitting raw data to a server for post-processing, and (c) storing processed data. Major operations controlled by the microprocessor include powering the sensor and initializing the collection of data.

Once data collection is initialized, the microprocessor is responsible for controlling a range of tasks by running scripts.These tasks might include quality assurance checks and displaying values in real-time as a single value or graphicallyas a time series. If a sensor does not have a built-in processorthat directly reports final measurements units, then the micro-processor is also required to convert a raw electrical signal tothe final units or direct the raw electrical signal to be transmittedto a server via cellular, Bluetooth, or cloud communication.

Post-processing data on a server allows algorithm updates tobe easily implemented across a network of sensor pods insteadof reprogramming sensor pods individually, but sensor podsshould still locally store data for quality assurance. Additionalprocessing might be required if data need to be averagedover a defined time interval. The final major task a micro-processor is responsible for includes storing either processedor unprocessed data.

Data can be stored locally in real-time either temporarily onthe processor or long-term on a secure digital (SD) memorycard. The available capacity of flash storage on microprocessorsis often very limited, so sensor pods that require data storageon the level of gigabytes (GB) or more should incorporateadditional internal storage. Local data storage requirements

are mainly determined by the number of sensors and param-eters being measured and the frequency and duration of thesampling. Our experience would indicate 4–8-GB SD cardsoften provide months of data logging capacity. As an example,we have observed 1-minute data collections for 10 variablestranslates to a rate of ~ 0.1 MB per day.

Remote data storage also helps minimize power requirementsbecause data do not have to be processed or stored locally.11-

12 Remote data storage can be redundant of locally storeddata or data processing/storage can be entirely remote withthe risk of communication failure potentially resulting in lostdata. The appropriate selection of a microprocessor is criticalto ensuring a sensor pod is capable of properly operating internal components, processing data to final units, and storing data.

Sensor SelectionWhen choosing an environmental sensor, it is important todefine performance specifications considering the expectedenvironmental conditions and the data quality requirementsof the end-user. This requires understanding the target pollu-tant’s expected range of concentrations during the durationof the project and the rate of fluctuation. The duration of theproject affects the impact of diurnal and seasonal trends, as well as the potential drift in a sensor’s response over time.Understanding these parameters is critical for proper sensorselection to ensure data are useful and appropriate.

The quality of the data collected by a sensor pod is a functionof the performance specifications of the internal sensors. Sensorswith a wide range of sampling frequencies are available andend-users need to define the specifications required toachieve the goals of the specific application. Important char-acteristics to consider during the design of sensor pods andthe performance specifications of various low-cost sensors arecovered in more detail in EPA’s Air Sensor Guidebook.13

Sensor pods could include a combination of sensors to measure particulate matter (PM), and/or gas-phase species,and environmental conditions. Many low-cost PM sensors arenephelometers that size particles in real-time based on lightscattering by an ensemble of particles at one or more specificwavelengths.6 Particles are measured via either active (e.g.,pump or fan) or passive (e.g., heated resistor or diffusion)sampling. The translation of the light scattering signal to mass is commonly done through a calibration against a massstandard or through collocation with a reference monitor.14

The second common PM sensor type is via an optical particlecounter, which counts and estimates the size of individualparticles as they pass through a laser beam. These sensors thentranslate the size-binned particle counts to mass by assumingthe particles are spherical and applying an assumed density.



matter (PM2.5), temperature, and RH. A primary requirementof the CSAM was to be capable of operating indoors and/oroutdoors on AC and/or battery (LiFePO4) power for oneweek unattended. For that reason, the CSAM units were designed to be fully automated by using a single-step key-lock access door to operate all functions simultaneously.

All of the sensors in the CSAM communicated and relayeddata through an Arduino Uno microprocessor via customsoftware that continuously stored all logged data to a SDmemory card. The CSAM was designed to function in bothoutdoor and indoor environments with minimal modifica-tions. When deployed indoors, the CSAM operated on ACpower with inert Teflon tubing used to extend the samplinginlets through windows to sample ambient conditions. Thesensors and battery were housed in separate National ElectricalManufacturers Association (NEMA)-approved boxes equippedwith rubber gaskets and a rain cover to be fully weather resistant. Aluminum materials were used for the housing, tripod, and rain shield to minimize weight and to prevent rust.

The CSAM measured NO2 in real-time in parts per billion(ppb) using a CairClip sensor, and PM2.5 in micrograms percubic meter (µg/m3) using a Thermo Scientific personalDataRam (pDR) 1200 nephelometer. Sensors selected for inclusion represented those useful in establishing potentialnear-road environmental conditions. The pDRs were modifiedfrom their original design by making them active samplersand amending their control board to accept on/off initiationinstructions from the CSAM. Air was actively sampled at aflow rate of 1.5 liter per minute (LPM) through a sharp-cutcyclone to exclude particles greater than 2.5 micrometers indiameter. Temperature and RH were measured inline by aHoneywell sensor (hih-4602-A/C series) to monitor environmental conditions.

Each CSAM unit included an embedded Microsoft Excelmacro-enabled spreadsheet to allow for the processing offield data. Following data collection, the user executed themacro, which resulted in the conversion of the voltagesrecorded for each sensor to the appropriate reporting units.The resulting spreadsheet contained the raw data, calibrationalgorithm, converted data, and time series for each sensor toallow the data to be assessed for quality and usability in auser-friendly manner.

During deployment, a collocation study was performed at theNCore network site maintained by the New Jersey Departmentof Environmental Protection (NJDEP) to compare four CSAMunits to Federal Reference Monitors. The internal NO2 andPM2.5 sensors were audited over a period of one week (April,7–April 14, 2015) against a TECO 42i sampler and a R&PTapered Element Oscillating Microbalance-Filter DynamicsMeasurement System (TEOM-FDMS), respectively.

Generally, PM sensors lack a true physical impactor and there-fore provide only estimations of size fraction concentrations.

Two common types of low-cost gas-phase sensors are electro-chemical and metal oxide.15,16 These sensors rely on chemicalreactions that produce electrical responses proportional to the concentration of the target pollutant. Metal-oxide sensorshave the advantage of high sensitivity across a wide range ofconcentrations relative to electrochemical sensors, but are influenced by cross sensitivity to other pollutants and are susceptible to drift.17

Measurements from both PM and gas-phase sensors havebeen shown to be influenced by changes in temperature and RH.7-9,19 To monitor changes in a sensor’s response, it isrecommended that sensor pods incorporate ambient temper-ature and RH sensors to ensure the readings are truly repre-sentative of the environment being sampled. Besides airquality sensors, other options of sensors not covered in depth include accelerometers, GPS, noise, and so forth.

Examples of Developed Sensor PodsEPA has been developing resources to help citizen scientistsexplore the air quality of their local communities and properlyconduct research to address potential environmental issues.Two examples of low-cost, cutting-edge air sensor pods aredescribed below: the Citizen Science Air Monitor (CSAM)and the AirMapper.

CSAMEPA developed the CSAM, as shown Figure 1, for an envi-ronmental justice research study in Newark, NJ, involving the measurement of nitrogen dioxide (NO2), fine particulate

Figure 1. The Citizen Science Air Monitor (CSAM)

showing the internal components.



Figure 2. The portable AirMapper with carrying

strap and touchscreen.

Each CSAM demonstrated good correlation with the referencemonitors for temperature (R2 > 0.92), RH (R2 > 0.88), NO2

(R2 > 0.62), and PM2.5 (R2 > 0.61). Individual regressionequations were derived for each CSAM to normalize the response between the reference monitors and the CSAM internal sensors. The deployment of the CSAM sensor podsat the study location from February 12, 2015, to July 30,2015 demonstrated that they could be operated by citizenscientists in a manner to provide reliable air quality informationwith only minor technical issues reported.

Lessons learned from the development and deployment ofthe CSAMs have been reported in depth elsewhere.3 Theseincluded miniaturization of the primary pod enclosure anduse of pod-specific printed circuit boards designed to improveelectrical architectural features. Overall, operation of theCSAMs and data recovery were effective. The operation ofthe CSAMs using the turnkey design allowed for minimaltraining and resulted in no issues with the citizen volunteers.Similarly, regularly changing batteries and switching to ACpower was successful.

AirMapperThe AirMapper, as shown in Figure 2, was designed as alightweight battery-powered portable sensor pod to measurePM1/PM2.5/PM10, carbon dioxide (CO2), temperature, RH,acceleration, noise, and location.18 The focus of the AirMapperwas to develop an environmental awareness sensor pod witha focus on ease of use to accommodate a wide range of enduser ages, including elementary school participants. For thisapplication, the data quality requirements were relaxed com-pared to a research application and a priority was high timeresolution data (10 seconds) to support fast data retrievalwhile walking or biking.

The AirMapper was constructed by modifying a commerciallyavailable bicycle commuter bag to add an aluminum case enclosure. The lightweight design (< 2 kg) and size (25 cm x20 cm x 25 cm) provided for the AirMapper to be eitherpersonally carried or used in a mobile fashion. Collected datawere processed using two coupled Arduino (Arduino Unoand Arduino Mega 2560) microprocessors, which supportedtwo components (touchscreen and PM sensor) that requireda serial interface. The data were logged to an internal SDcard and could also be viewed in real time through a touch-screen interface. Data were logged in 10-second intervalsand automatically processed to report in a format compatiblewith the Real-Time GeOspatial viewer (RETIGO) data visuali-zation tool,20 which could be used to explore trends andchanges in data. The AirMapper can run on battery for approximately 8 hours using a 7.2V rechargeable NiMH battery pack (recharge time of ~ 4 hrs).

On-board the AirMapper, PM was measured in units ofµg/m3 using an AlphaSense OPC-N2 optical particle monitor,which pulled ambient air into the sensor via a fan. CO2 wasmeasured in units of parts per million (ppm) using a COZIRsensor (GC-0015) using nondispersive infrared sampling.Both temperature and RH were measured by an Adafruitsensor (DHT22). The AirMapper also measured noise(MAX9814 Chip), acceleration (ADXL326), and longitudeand latitude coordinates (Ultimate GPS module).

EPA released the AirMapper for pilot testing by three EPA regional offices. Early feedback from community groups andEPA users indicated that the AirMapper is user-friendly andthe immediate interactive data exploration via RETIGO pro-vided an enhanced educational experience. When releasingthe AirMapper to specific EPA regional offices, the agencyalso provided educational lessons directly to them, whichaligned with national science standards. Such education materials are available upon direct request.

Future ConsiderationsTo continue the advancement of emerging low-cost sensorpods, several key aspects must be addressed. A mechanismis needed to inform users of commercially available sensorsthat have been evaluated against Federal Reference Monitorsto establish performance specifications. EPA’s Air Sensor Tool-box21 and South Coast Air Quality Management District’s(SCAQMD) AQ-SPEC22 program are examples of methodsof communication useful in conveying performance specifications of low-cost sensors to end users.

Stephen Reece is with Oak Ridge Institute for Science and Education. ORISE Participant, Oak Ridge, TN; Amanda Kaufman iswith the U.S. Environmental Protection Agency’s (EPA) Office of Air Quality Planning & Standards, Research Triangle Park, NC; andGayle Hagler and Ronald Williams are both with EPA’s National Exposure Research Laboratory, Research Triangle Park, NC.

Disclaimer: The U.S. Environmental Protection Agency (EPA) through its Office of Research and Development funded and conducted the research described here. This article has been reviewed by EPA and approved for publication. Mention of tradenames or commercial products does not constitute endorsement or recommendation for use. The authors have no conflicts ofinterest or financial ties to disclose.

References1. Kura, B.; Verma, S.; Ajdari, E.; Iyer, A. Growing Public Health Concerns from Poor Urban Air Quality: Strategies for Sustainable Urban Living; Computational

Water, Energy, and Environmental Engineering 2013, 2, 1-9.2. Judge, R.; Wayland, R. Regulatory Considerations of Lower Cost Air Pollution Sensor Data Performance; EM, August 2014, 32-37.3. Kaufman, A.; Williams, R.; Barzyk, T.; Greenberg, M.; O’Shea, M.; Sheridan, P.; Hoang, A.; Ash, C.; Teitz, A.; Mustafa, M.; Garvey, S. A Citizen Science and

Government Collaboration: Developing Tools to Facilitate Community Air Monitoring; Environ. Justice 2017, 10 (2), 51-61.4. Snyder, E.G.; Watkins, T.H.; Solomon, P.A.; Thoma, E.D.; Williams, R.W.; Hagler, G.S.W.; Shelow, D.; Hindin, D.A.; Kilaru, V.J.; Preuss, P.W. The Changing

Paradigm of Air Pollution Monitoring; Environ. Sci. Technol. 2013, (47), 11369-11377.5. French, R. Public Participation in Air Quality Monitoring: A New Frontier in Citizen Science; EM, August 2014, 16-21.6. Jiao, W.; Hagler, G.; Williams, R.; Sharpe, R.; Brown, R.; Garver, D.; Judge, R.; Caudill, M.; Rickard, J.; Davis, M.; Weinstock, L.; Zimmer-Dauphinee, S.; Buckley,

K. Community Air Sensor Network (CAIRSENSE) project: Evaluation of low-cost sensor performance in a suburban environment in the southeastern UnitedStates; Atmos. Meas. Tech. 2016, (9), 5281-5292.

7. Wang, Y.; Li, J.; Jing, H.; Zhang, Q.; Jiang, J.; Biswas, P. Laboratory Evaluation and Calibration of Three Low-Cost Particle Sensors for Particulate Matter Measurement; Aerosol Sci. Technol. 2015, (49), 1063-1077.

8. Williams, R.; Long, R.; Beaver, M.; Kaufman, A.; Zeiger, F.; Heimbinder, M.; Hang, I.; Yap, R.; Acharya, B.; Ginwald, B.; Kupcho, K.; Robinson, S.; Zaouak, O.;Aubert, B.; Hannigan, M.; Piedrahita, R.; Masson, N.; Moran, B.; Rook, M.; Heppner, P.; Cogar, C.; Nikzad, N.; Griswold, W. Sensor Evaluation Report;EPA/600/R-14/143; U.S. Environmental Protection Agency, Washington, DC, May 2014.

9. Williams, R.; Kaufman, A.; Hanley, T.; Rice, J.; Garvey, S. Evaluation of Field-deployed Low Cost PM Sensors; EPA/600/R-14/464; U.S. Environmental ProtectionAgency, Washington, DC, December 2014.

10. Polidori, A.; Papapostolou, V.; Zhang, H. Laboratory Evaluation of Low-Cost Air Quality Sensors; South Coast Air Quality Management District, Diamond Bar,CA, August 2016.

11. Kotsev, A.; Schade, S.; Craglia, M.; Gerboles, M.; Spinelle, L.; Signorini, M. Next-Generation Air Quality Platform: Openness and Interoperability for the Internetof Things; Sensors 2016, 16 (3).

12. Kremens, R.L.; Gallagher, A.J.; Seema, A.; Low-Cost Autonomous Field-Deployable Environment Sensors; AIP 2002, 636 (1), 190-199.13. Williams, R.; Kilaru, V.; Snyder, E.; Kaufman, A.; Dye, T.; Rutter, R.; Russell, A.; Hafner, H. Air Sensor Guidebook; EPA/600/R-14/159; U.S. Environmental

Protection Agency, Washington, DC, June 9, 2014.14. Northcross, A.L.; Edwards, R.J.; Johnson, M.A.; Wang, Z.-M.; Zhu, K.; Allen, T.; Smith, K.R. A low-cost particle counter as a real-time fine-particle mass monitor;

Environ. Sci: Process. Impacts 2013, (15), 433-439.15. Fine, G.F.; Cavanagh, L.M.; Afonja, A.; Binions, R. Metal Oxide Semi-Conductor Gas Sensors in Environmental Monitoring; Sensors 2010, (10), 5469-5502.16. Stetter, J.R.; Li, J. Amperometric Gas Sensors: A Review; Chem. Rev. 2008, (108), 352-366.17. Aleixandre, M.; Gerboles, M. Review of small commercial sensors for indicative monitoring of ambient gas; Chem. Eng. Trans. 2012, (30), 169-174.18. Village Green and AirMapper Fact Sheet; U.S. Environmental Protection Agency, Office of Research and Development, 2016. See

https://www.epa.gov/sites/production/files/2016-04/documents/village_green_and_airmapper_fact_sheet_0.pdf (accessed August 4, 2017).19. Spinelle, L.; Gerboles, M.; Aleixandre, M.; Bonavitacola, F. Evaluation of metal oxides sensors for the monitoring of O3 in ambient air at ppb level; Chem.

Eng. Trans. 2016, (54), 319-324.20. Real Time Geospatial Data Viewer (RETIGO). See https://www.epa.gov/hesc/real-time-geospatial-data-viewer-retigo (accessed May 23, 2017).21. Kaufman, A.; Brown, A.; Barzyk, T.; Williams, R. The Citizen Science Toolbox: A One-Stop Resource for Air Sensor Technology; EM, September 2014, 48-49.22. Air Quality Sensor Performance Evaluation Center; South Coast Air Quality Management District [Online]. See http://www.aqmd.gov/aq-spec/evaluations

(accessed August 4, 2017).23. Williams, R.; Watkins, T.; Long, R. Low-Cost Sensor Calibration Options; EM, January 2014, 10-15.24. Rea, A.W.; Zufall, M.J.; Williams, R.W.; Sheldon, L.; Howard-Reed, C. The Influence of Human Activity Patterns on Personal PM Exposure: A Comparative

Analysis of Filter-Based and Continuous Particle Measurements; J. Air & Waste Manage. Assoc. 2001, (51), 1271-1279.



Establishing benchmark performance criteria would provide a pathway for emerging technologies to achieve certification.This would create a clear means for users to identify sensorsthat meet defined performance standards. In addition, estab-lishing data and metadata standards for low-cost sensorswould improve interoperability, software, and databases. Manylow-cost sensors currently lack an affordable and simplisticmeans of calibration. The most widely practiced method is todo a collocation study against a reference monitor prior inorder to normalize sensor data relative to the reference monitor.23,24 Field calibrations also allow sensor pods to becalibrated under real-world conditions rather than under factory and laboratory settings. This option helps address

data quality concerns but is probably not feasible for inexperienced end users without support from third-party applications and custom field calibrations.

Based on the examples described here, multipollutant sensorpods can provide value to environmental air quality awarenessstudies. Key decisions about component selection are requiredearly in the design process. Knowledge about the capabilitiesof the sensors of interest is vital in ensuring a device meetingits proposed use is developed. Understanding how the tech-nology functions and then integrating the components into afunctional design requires technical expertise often not availableat the citizen or community level. em

The latest on the EPA’s ongoing project to define the term “solid waste” in the

context of regulating the recycling of hazardous secondary materials.

Solid WasteWhat’s in a Name?

by Anthony B. Cavender

Etcetera


On July 7, 2017, the U.S. Court of Appeals for the District of Columbia issued its latest ruling on the U.S. EnvironmentalProtection Agency’s (EPA) ongoing project to define the term“solid waste” in the context of regulating the recycling of“hazardous secondary materials”. This decision, American Petroleum Institute v. EPA, rejected some important provisionsor components of the agency’s latest effort, promulgated in2015, to regulate these recyclable materials, whose manage-ment is a serious and ongoing concern for many industries.For more than 30 years, EPA has attempted—with only somesuccess—to conclusively define solid waste, which is of funda-mental importance to the implementation and enforcement

of the Resource Conservation and Recovery Act (RCRA) andthe regulation of hazardous and solid waste.

EPA’s efforts have been made more difficult by the statute’sdefinition of solid waste, which references not only garbage,refuse and sludge, but also “other discarded materials”. Thelatter phrase is ambiguous and has presented considerablechallenges to the agency when it confronts the issue of howto approach recycling operations, which can be a pretext fordisposal operations that the law requires to be regulated. The agency has decided that it must comprehensively define“solid waste” so as to regulate only materials that are truly

discarded, while allowing legitimate recycling operations toproceed to adhere to RCRA’s stated policy of promoting therecovery of materials that are valuable and need not beburied in landfills. As a result, over the years, EPA has notonly defined solid waste in its RCRA rules, but has also mademany separate exclusions to this definition. Those excludedmaterials are not, by definition, solid waste, and are thereforenot subject to RCRA’s stringent RCRA regulatory controls.


Etcetera

recycled” are automatically considered to be discarded andsolid waste;

5. changed the 2008 definition of “legitimate recycling”; and 6. substantially revised the procedures by which a solid waste

variance or non-waste determination will be made.

Most of these changes were not disturbed by the July meeting.

BackgroundSince the early 1980s, EPA has tried to reform, reduce, andrelax the regulatory obstacles to the reclamation and recoveryof valuable byproducts generated by manufacturing and otherindustrial practices and operations. On December 10, 2014,the then-EPA Administrator signed a final rule, which againrevised the agency’s regulatory definition of “solid waste,”which is the lynchpin of EPA’s authority to regulate the man-agement of hazardous waste. (Note: The rule was publishedin the Federal Register on January 13, 2015.)

This action reversed the modest regulatory actions taken byEPA in October 2008 to encourage the legitimate recyclingof “hazardous secondary materials” that would otherwise besubject to EPA’s very strict and complex RCRA Subtitle C hazardous waste rules. The agency states that it revised the2008 rules because it was concerned that the application ofthose rules would increase risk to human health and the environment from discarded hazardous secondary materialswithout additional safeguards. The many conditions that EPAplaced on the new recycling exclusions in 2008 were mademore prescriptive, to the extent that the conditions attendinga proposed recycling activity are similar in scope and complex-ity to the rules that apply to permitted RCRA treatment, storage and disposal facilities.

The 2015 RulesUnder the 2015 rules, EPA took the following actions: 1. amended the “generator-controlled exclusion”; 2. replaced the “transfer-based exclusion” with a new

“verified recycler exclusion”; 3. established a new “remanufacturing exclusion” to permit

the controlled reclamation of specifically listed solvents; 4. codified the agency’s long-standing policy that hazardous

secondary materials determined to have been “sham

The 2015 rules considerably tightened the 2008 recyclingexclusions. For example, the “generator-controlled” exclusionwas revised by providing that the reclamation process mustmeet the revised definition of “legitimate recycling” and EPAsubstantially revised the “speculative accumulation” rule. Inaddition, this exclusion mandated adherence to new record-keeping requirements, expanded notification requirements,new emergency response and preparedness conditions, andhazardous secondary materials must be managed in unitsthat satisfy the new “contained” definition.

Much of the 2008 “transfer-based exclusion” was jettisoned,and generators who wish to take advantage of this exclusionwould be obliged to use the services of a third-party “verifiedrecycler” that has obtained either a federal or state authorizationand has proof of financial responsibility. The new “remanufac-turing exclusion” will permit the reclamation of specific hazardous secondary materials that are listed high-value solvents—these materials will not be considered solid wastes ifthey are processed in accordance with this rule. New notificationrequirements also apply to this new exclusion, and the remanufacturing facility must prepare and follow a satisfactory“remanufacturing plan,” whose criteria are spelled out in therule. In addition, these solvent reclamation facilities must ad-here to complex and extraordinarily-detailed U.S. Clean AirAct emission control requirements that are modeled on theexisting requirements applicable to certain RCRA-permittedor authorized units.

In addition, EPA took the following steps:

1. included a provision that the EPA Administrator’s decisionwhether to grant a petition seeking a variance from a mate-rial’s classification as a “solid waste” that is being reclaimedby a verified recycler will depend on whether the reclamation

For more than 30 years, EPA has

attempted—with only some success—

to conclusively define solid waste.

Etcetera


or intermediate facility’s petition addresses the “potentialfor risk to proximate populations from unpermitted releases…and must include consideration of potential cumulative risks from nearby stressors” (this new provisionappears to address some of the environmental justice concerns the agency has grappled with over the years);

2. added that, any variance or non-waste determination willbe effective for no more than 10 years, which is consistentwith the length of a RCRA permit;

3. stated the new definition of “contained” provides that acompliant unit must address “any potential risks of fires orexplosions,” which EPA states will make spent petroleumcatalysts eligible for inclusion in the generator-controlledexclusion; and

4. deferred, for the time being, a review of all pre-2008 recycling exclusions.

The D.C. Court RulesThe American Petroleum Institute v. EPA decision reviewedonly four issues from EPA’s 2015 rulemaking: the revisionand expansion of the legitimacy factors EPA uses to policesham recycling operations that are in truth another way todispose of discarded materials; making spent catalystsamenable to its own exclusion from strict RCRA hazardouswaste regulation; deferring for another time whether to subject all previous regulatory exclusions (of which there aremore than 20) to the new 2015 conditions; and replacingthe 2008 Transfer-based Exclusion with the Verified Recycler Exclusion.

In its opinion, the D.C. Court of Appeals upheld most of EPA’snew “legitimate recycling criteria,” set forth at 40 C.F.R. §260.43(a) (https://www.ecfr.gov/cgi-bin/text-idx?SID=f1af4d7aa546d340a59c98df057dfa46&node=40:26.0.1.1.1.3.1.13&rgn=div8), except for Factor 4 which the court held imposed unacceptably “draconian” conditions on recyclers;vacated the Verified Recycler Exclusion set forth at 40 C.F.R.§ 261.1(a)(24) (https://www.ecfr.gov/cgi-bin/text-idx?SID=77e67a5e0d111f49766e5ef25b0084b0&mc=true&node=se40.28.261_11&rgn=div8) with some exceptions; and reinstated the 2008 Transfer-based Exclusion and vacated arecycling bar that affected spent catalysts. The arguments ofthe environmental petitioners were rejected, as was industry’sargument, mistaken according to the court, that the legitimacyfactors should also be vacated as to Used Oil Recycling. According to the court, all the parties agreed that some formof legitimate third party reclamation would be consistent withthe statute, but EPA’s new advance administrative approval requirements in the Verified Recycler Exclusion were not

adequately justified as required by the Administrative Procedure Act and many decisions of the D.C. Circuit.

What Are the Results of the Ruling?The bulk of the new recycling/reclamation rules are noweffective, subject of course, to additional litigation. These rules include:

1. New and revised definitions of “facility,” “hazardoussecondary material,” “contained,” and “remanufacturing”(40 CFR Section 260.10);

2. Non-waste determination procedures (40 CFR Section260.34);

3. Notification requirements for hazardous secondarymaterials (40 CFR Section 260.42);

4. Legitimate recycling criteria—as revised by the court (40 CFR Section 260.43);

5. Definitions of materials “reclaimed” and “accumulatedspeculatively” (40 CFR Section 261.1);

6. New exclusions promulgated for material not consideredsolid waste, as revised by the court (40 CFR Section 261.4(a);

7. Financial Assurance requirements for owners andoperators of facilities reclaiming hazardous secondarymaterial (40 CFR Section 261.140-151); and

8. New standards applicable to remanufacturing units andequipment managing hazardous secondary material (40 CFR Section 261.170-1089).

It is likely that there will be additional litigation in this case.For one thing, the court’s discussion of the uncertain regulatorstatus of spent catalysts included an invitation to the partiesto file petitions for rehearing on this issue to give the court anopportunity to issue a clarifying opinion, and several petitionshave been filed.

After these petitions are addressed, the next issue to bedetermined is whether and when the new rules will be effectivein states having delegated RCRA authority. Not all stateshave adopted either the 2008 or 2015 rules, and steps mustbe taken in these states to revise or modify their existingRCRA rules to incorporate these changes. Pursuant to RCRA,the new rules will be immediately effective in those few statesthat do not have a final RCRA delegation, but the complexityof the RCRA delegation program means that the determinationof the status of these rules in the other states must proceedcarefully on a state-by-state basis. These rules are unusuallycomplex, and all parties must be especially cautious inworking with them. em

Anthony B. Cavender is Senior Counsel for Environment, Land Use, and Natural Resources at Pillsbury Law. E-mail: [email protected].

LDEQ’s MAML is a fully-functional laboratory on wheels.

Sensor OverloadLDEQ’s Mobile Air Monitoring Laboratory

by Nathan McBride

YP Perspective


Since 2006, the Louisiana Department of EnvironmentalQuality (LDEQ) has deployed the Mobile Air MonitoringLaboratory (MAML) to locations across the state of Louisianato monitor air quality and to assist with incident response.

The MAML (pronounced “mammal”) is a converted Winnebagorecreational vehicle, equipped with an array of air monitoringsensors and analyzers. These sensors and analyzers can detectand monitor for criteria air pollutants (i.e., ozone, particulatematter, carbon monoxide, nitrogen oxides, and sulfur dioxide,

as defined by the U.S. Environmental Protection Agency[EPA]), airborne mercury, hydrogen sulfide, and a variety ofvolatile organic compounds (VOCs) at very low concentrations—in parts per billion (ppb), in many cases.

Whenever applicable, all of the equipment and data collection activities onboard the MAML meet any and all EPA specificationsor equivalent method requirements. To maintain compliance withEPA standards and to ensure accuracy of measurements, muchof the equipment requires daily calibration.

YP Perspective


Arguably the most impressive component in the MAML’s arsenal of pollutant sensors is the onboard gas chromatograph/mass spectrometer. A gas chromatograph is an instrumentthat analyzes a sample by separating it into its individualchemical constituents, which are then passed through sometype of electronic analyzer to determine the makeup andconcentrations of each compound. A mass spectrometer essentially organizes—through a complex process involvingionization—the chemical constituents of a sample based onmass to provide an extremely accurate assessment of complexmixtures, in this case, an air sample. A gas chromatograph/mass spectrometer is an instrument that combines these twotechnologies into a single, integrated package.

The mobile lab originally came equipped with a standalonegas chromatograph, but the department decided the additionalanalyzing capabilities of an integrated mass spectrometerwould outweigh the added cost and required maintenance of the more complex instrument. Since making that decision,LDEQ upgraded the MAML to include an Agilent 7890Agas chromatograph equipped with an Agilent 5975C massspectrometer. This analyzer is capable of detecting 55 uniqueorganic compounds at concentrations as low as 0.5 ppb.

A piece of equipment like this is typically found in traditional,brick-and-mortar laboratories, and having one on wheels is aconsiderable benefit to LDEQ when it comes to environmentalmonitoring. The primary purpose of this analyzer onboardthe MAML is the detection of VOCs, which is critical duringincident response scenarios and significant in the overall pollution monitoring program.

The MAML can collect and analyze canister samples and canperform real-time, continuous analysis of air samples takenthrough a collection manifold. It also comes equipped withan onboard computing station for analyzing data and writingreports, which truly makes the MAML a fully-functional labo-ratory on wheels. The two onboard generators and kitchenallow for continuous operations, even in remote areas.

It has its own meteorological station, which technicians use to account for weather conditions and for assistance in deter-mining optimal placement of the MAML in each monitoringscenario. The positioning of a monitoring station is especiallycritical when assisting with emergency response following an environmental incident or release, which is one of theMAML’s primary functions.

It also serves as a mobile component in LDEQ’s network offixed pollution monitors stationed throughout the state. Inthe event of an exceedance at one of the state’s fixed monitors,LDEQ may dispatch the MAML to assist with further investi-gation or validation of the exceedance.

The MAML is also used to investigate citizen complaints orto gather information as needed by LDEQ or requested bythe regulated community. This allows the department toidentify potential areas of concern before serious problemsmay arise, without the expense or time required to constructa fixed monitoring site.

Currently, there is one MAML deployed in the state ofLouisiana. It was purchased through grants from state andlocal entities, but with a price tag of between $500,000 and$600,000, it will be a tall task for LDEQ to purchase a newone with the department’s current budget.

Louisiana does have a program, however, that allows privatecompanies to cover the cost of a new MAML. This programallows companies to complete Beneficial Environmental Projects(BEPs), such as a pollution study, a wetlands restoration project,or the purchase of a new MAML, as part of settlementagreements to resolve enforcement actions. A BEP for thepurchase of a MAML has been approved by LDEQ, andhopefully very soon a second MAML will be added to thefleet. This would instantly allow for much greater flexibilityand enhance LDEQ’s ability to protect the environment in the state of Louisiana. em

Nathan McBride is with Louisiana Mid-Continent Oil and Gas. E-mail: [email protected].

YP Perspective is a regular column organized by A&WMA’s Young Professional Advisory Council (YPAC). YPAC strives toeffectively engage professionals within the Association by developing services and activities to meet the needs of today’syoung professionals (YPs). A YP is defined by the Association as being 35 years of age or younger. Each YP is encouragedto get involved with the Association, whether within their local Chapter or Section or within the Association’s four Councils(Education Council, Technical Council, Sections and Chapters Council, and YPAC). YPs interested in getting involved maycontact YPAC for more information on current volunteer and leadership opportunities.

Call for Submissions: If you have a topic you would like to see YPs discuss and/or you would like to volunteer as an author, e-mail: Christopher Whitehead at [email protected].

Nov. 25, 1920: The Philadelphia Thanksgiving Day Parade is the longest-running in the United States, starting on this date.

Nov. 30, 2009: CERN (European Organization for Nuclear Research) was established on this date.

Nov. 22, 1954: The Humane Society of the United States formed.

This Month in History

This Month in History (and other fun facts)

The name November is believed to derive from “novem,” which is the Latin for the number nine.In the ancient Roman calendar, November was the ninth month after March.

November’s gem is Topaz, and its flower is Chrysanthemum.

Finnish: Marraskuu

Icelandic: Nóvember

Polish: Listopad

Spanish: De Novembre

Welsh: Tachwedd

Nov. 8, 1731: In Philadelphia, BenjaminFranklin (with members of his Junto Club) opened the first library in the United States.

Nov. 24, 1859: Charles Darwin published On the Origin of Species.

Nov. 1, 1512: Michelangelo’s paintings on the ceiling of Sistine Chapel in Vatican City, Italy were first exhibited. He started the work in 1508.

Did You Know?

Last Stop



A&WMA HeadquartersStephanie M. GlyptisExecutive DirectorAir & Waste Management AssociationOne Gateway Center, 3rd Floor420 Fort Duquesne Blvd.Pittsburgh, PA 15222-14351-412-232-3444; 412-232-3450 (fax)[email protected]

AdvertisingJeff [email protected]

EditorialLisa BucherManaging [email protected]

Editorial Advisory CommitteeJohn D. Kinsman, ChairEdison Electric InstituteTerm Ends: 2019

Teresa Raine, Vice ChairERMTerm Ends: 2020

Robert BaslEHS Technology GroupTerm Ends: 2019

Leiran BitonU.S. Environmental Protection AgencyTerm Ends: 2019

Gary Bramble, P.E.AESTerm Ends: 2018

Bryan ComerInternational Council on Clean TransportationTerm Ends: 2020

Prakash Doraiswamy, Ph.D.RTI InternationalTerm Ends: 2020

Layout and Design: Clay Communications, 1.412.704.7897

EM, a publication of the Air & Waste Management Association, is published monthly with editorial and executive offices at OneGateway Center, 3rd Floor, 420 Fort Duquesne Blvd., Pittsburgh, PA 15222-1435, USA. ©2017 Air & Waste Management Asso-ciation (www.awma.org). All rights reserved. Materials may not be reproduced, redistributed, or translated in any form withoutprior written permission of the Editor. A&WMA assumes no responsibility for statements and opinions advanced by contributorsto this publication. Views expressed in editorials are those of the author and do not necessarily represent an official position ofthe Association. A&WMA does not endorse any company, product, or service appearing in third-party advertising.

EM Magazine (Online) ISSN 2470-4741 » EM Magazine (Print) ISSN 1088-9981

Staff and ContributorsAli FarnoudRamboll EnvironTerm Ends: 2020

Steven P. Frysinger, Ph.D.James Madison UniversityTerm Ends: 2018

Keith GaydoshAffinity ConsultantsTerm Ends: 2018

C. Arthur Gray, IIIAmazon.com Inc.Term Ends: 2019

Jennifer K. KelleyGeneral ElectricTerm Ends: 2020

Mingming LuUniversity of CincinnatiTerm Ends: 2019

David H. Minott, QEP, CCMArc5 Environmental ConsultingTerm Ends: 2020

Brian Noel, P.E.Trinity ConsultantsTerm Ends: 2020

Anthony J. Sadar, CCMAllegheny County Health DepartmentTerm Ends: 2018

Golam SarwarU.S. Environmental Protection AgencyTerm Ends: 2019

Anthony J. Schroeder, CCM, CMTrinity ConsultantsTerm Ends: 2019

Susan S.G. WiermanMid-Atlantic Regional Air Management AssociationTerm Ends: 2018

James J. Winebrake, Ph.D.Rochester Institute of TechnologyTerm Ends: 2018

The Magazine for Environmental Managers

continued development and uncertainties with next …pubs.awma.org/flip/em-nov-2017/emnov17.pdf ·...

Documents