Air Toxics Monitoring in the Houston-Galveston Area

David Brymer, Texas Commission on Environmental Quality

General Monitoring Information

• >140 monitors (not including weather) at >45 fixed air monitoring sites in the Houston-Galveston area

• >25,000,000 air quality measurements

This represents almost a third of the fixed site air monitoring done in the State of Texas

Continuous Monitoring Sites

www.tceq.state.tx.us/subject/subject_air.html

Topics of Discussion

• Who is doing this monitoring?• Where are we monitoring Air Toxics?

– Network Design (why are we monitoring where we are?)

• What compounds are we monitoring?• How are we monitoring Air Toxics?

– Types of monitoring– Technology used/ Sampling frequency

Who Does this Monitoring?• Governmental Agencies

– EPA

– TCEQ

– Local Governments (HCPC, GCHD, etc..)

• Citizen Groups • Industry

– Consortiums (HRM)

– Individual facility fenceline and/or on-site monitoring

Network Design

• Fixed sites – Sited to address a specific monitoring objective

• Mobile sites – Screening or addressing a specific concern/

incident– Upwind/downwind

Fixed Air Toxics Monitoring Sites in the Greater Houston-Galveston Area

EISM Sites

HRM Sites

TCEQ Sites

Other

Air Toxics Related Projects with Fixed Sites

• National Air Toxics Trends Sites (NATTS) – EPA• Photochemical Assessment Monitoring Stations

(PAMS) – EPA• Community Air Toxics Monitoring Network

(CATMN) – State• Houston Regional Monitoring Network – Industry• Supplemental Environmental Projects/Agreed

Order Monitoring – Gov’t/Industry

CATMN

• Legislative directive in 1992

• Assess community exposure to VOC concentrations

• Determine potential long-term health effects

• Data used to assess temporal/spatial variability

CATMN Site Considerations

• Magnitude of pollution emissions within 10 km radius

• Predominant wind direction/wind rose• Population density• Traffic patterns• Degree of public concern• Logistical considerations

– 40 CFR Part 58, App. D & E– Access to the site

• Available data – mobile monitoring

Toxics Monitoring Sites

Air Toxics Monitoring Sites

Houston/Beaumont CATMN

PAMS Monitoring

– Monitoring required in non-attainment areas (1990 CAA Section 182[c][1])

– Enhanced monitoring of ozone, its precursors (VOCs which include some air toxics & NOx) and influencing factors (meteorology and solar radiation)

– In the Houston area this requirement includes upwind (Galveston), area of anticipated max VOC emissions (Clinton Dr), and downwind (Aldine)

National Air Toxics Monitoring Strategy

• Urban Air Toxics Strategy (UATS) -1999• Attain substantial reduction of Non-cancer HAPs• Attain 75% reduction of cancer drivers from 1993

levels

• Monitoring Goals– Trends– Exposure Assessments (ambient measurements as a

surrogate for actual human exposure)– Air Quality Model Evaluation

22 NATTS sites– 15 urban (1 in Tx – Deer Park)– 7 rural (1 in Tx – Karnac)

What Compounds are Being Monitored?

• Criteria Pollutants (ozone, particulate, CO, SO2, NO2, and lead)

• Volatile Organic Compounds – 1 to over 150 compounds at a given site– Includes HRVOCs and air toxics at most sites– Dependent upon monitoring method and

project/site objectives

What are Hazardous Air Pollutants (HAPs)?

• Hazardous air pollutants are those pollutants that are known or suspected to cause cancer or other serious health effects or adverse environmental effects, Source: EPA.

• EPA classified 188 compounds as HAPs in the 1990 Clean Air Act Amendments

• The National Air Toxics Assessment (NATA) study done by EPA in 1990 identified 6 risk drivers of particular interest nationwide.– VOCs – benzene, 1,3-butadiene, acrolein,

formaldehyde– Metals – chromium* and arsenic

• The 1999 NATA study using 1996 data did not identify 1,3-butadiene and arsenic as national risk drivers

Sources of Air Toxics

• Mobile sources • Stationary point sources• Indoor sources • Area sources such as lawn mowing,

heavy machinery, dry cleaners, and printing operations

• Atmospheric reaction products

Where are HAPs Monitored in Houston?

There are 32 TCEQ or industry-funded ambient air toxics monitors in the HGB area (not including SEP & Agreed Order monitoring)

Source: TCEQ

County City, Site

Hourly AutoGC VOCs

24-hour Canister VOCs

1-hour Canister VOCs

24-hour Carbonyls

1-hour Carbonyls

24-hour Metals

Clute, Cobb Field XDanciger, EISM XLake Jackson, EISM XLiverpool, Mustang Bayou, EISM X

Mont Belvieu, HRM XBaytown East, HRM X

Galveston, Airport X X XTexas City, Ball Park XTexas City, Nessler Pool X XTexas City, EISM X

Aldine X XBaytown XBaytown West, HRM XBaytown, Lynchburg Ferry XBaytown, Lynchburg Ferry, HRM XBaytown, Wallisville Rd., HRM XChannelview X X X X XGalena Park XHouston East XHouston, Central Street, HRM XHouston, Clinton Dr. X X X X XHouston, Deer Park #2 X X X X XHouston, Galleria X XHouston, Haden Rd. XHouston, Haden Rd., HRM X XHouston, Milby Park X XHouston, NW Harris County X XHouston, Sheldon Rd., HRM XLa Porte, HRM XLa Porte, San Jacinto Monument XLa Porte, Shore Acres X

Montgomery Conroe, re-located X

Harris

Brazoria

Galveston

Chambers

Houston-Galveston Area HAP Monitors

Legend

TCEQ & EISM sites

HRM sites

How are We Doing Fixed Site Monitoring?

• VOCs (including benzene, 1,3-butadiene)– Automated Gas Chromatographs (11sites) – Passivated Canisters (24 sites)

How are we Doing Fixed Site Monitoring?

• Carbonyls ( including formaldehyde, acrolein)– DNPH cartridge collection and HPLC analysis

– 3 sites

• Metals– Filter collection

and ICP analysis

– 8 sites

VOC Monitoring Approaches

• AutoGC’s– Provide hourly measurements – Provide sub ppbV detection limits– Preliminary data available within 2 hrs – Provides data on HRVOCs and air toxics– Limited target list (non-polar compounds)– Only 1 shot at the analysis– Large capital investment– Generates approx. 500,000 data points/yr

VOC Monitoring Approaches

• Canisters– Can be configured for a wide variety of sample

collection times (<1 min to > 1 day). We generally use 24 hr samples collected every 6th day.

– Can be analyzed for a wide variety of compounds (>100 target compounds).

– Lower initial and on-going costs.– Provide sub ppbV level detection limits with the

ability to reanalyze or dilute a sample – Samples sent back to a lab for analysis. Results are

not available in real-time or near real-time.

VOC Monitoring with Canisters

Event Triggered Can Sampler

Mobile Site Monitoring

• Mobile Laboratory Monitoring (In Field)– TCEQ

• Screening/Incident Monitoring– EPA – TCEQ

• HCPC

• GCPC

• Citizen groups

Mobile Laboratory Capabilities

• Volatile Organics– Screening with portable

GC/MS and other handheld instrumentation (soon to include IR camera)

– In field analysis using GC/PID/FID

– Confirmational sampling via canisters and GC/MS analysis

What is TCEQs Mobile Laboratories Role?

• Find contributors to elevated ambient concentrations measured at fixed sites

• Determine compliance with H2S/SO2/particulate Regulations

• Respond to ongoing complaints that appear to match monitoring capabilities

• Collect enforcement quality data• Identify/quantify air toxics in specific areas

When Roles Do TCEQs Mobile Laboratories not Fill?

• Emergency response (timing, safety, response time)

• General odor complaints (don’t do nuisance odor investigations - can analyze for H2S/SO and organics)

• Source sampling (in most cases)• Not great at monitoring intermittent or

batch operations

Screening/Incident Investigation

• Agency investigators can use screening tools (IR cameras, TVA, OVA,etc) or collect samples (e.g. canisters) that can be sent to lab for analysis

• Citizen group screening