Air Pollution: Outdoor

Environmental Effects

• Affects plant growth (productivity), crop yields and disrupts food web

• Acidification of aquatic ecosystems, eutrophication

• Amphibians and lichens are especially sensitive (good indicator species)

• Decreases visibility and clarity

Human Health Effects

• Acute– irritation of eyes, skin, and respiratory system– Aggravates asthma and emphysema (COPD),

contributes to CV disease– Increases susceptibility to respiratory infection

(pneumonia, bronchitis)

• Chronic:– permanently decreases lung function, raises risk

of lung cancer

Human Health Effects

• Children are especially affected• Synergistic effects: multiple sources working

together, negative effects magnified– especially affect urban dwellers, some

occupations like miners and textile workers

Human Respiratory System

• Major function is to exchange gases with environment.

• Major organs: lungs• actual exchange of

gases occurs through diffusion

Your Body’s Natural Defenses against Air Pollution Can Be Overwhelmed

• Respiratory system protection from air pollutants– Hairs in your nose – filter out large particles– Mucus – capture smaller particles– Sneezing and coughing – expels contaminated air– Cilia (tiny hairs) – move mucus to throat to be

swallowed or expelled.

Human Respiratory System

• Respiratory problems affected by air pollution:– asthma– chronic bronchitis– lung cancer– emphysema

Sources of Air Pollutants

Natural Sources• Volcanoes• Pollen• Microorganisms• Dust• Storms• Wildfires

Sources of Air Pollution

• Anthropogenic sources = human caused– From transportation, power plants, industry

Anthropogenic Sources

• Stationary– Fixed.– Ex: Power Plant

• Mobile– Moving– Ex: Car, plane, ship

Anthropogenic Sources• Point Source

– Single, identifiable, localized

– Ex: smokestack• Non-point or area source

– From diffuse sources, hard to pinpoint

– Ex: buildings with multiple vents

– Fugitive emissions: emitted from factory somewhere along the way

Point vs. Non-point

Anthropogenic Sources

• Primary pollutants– Released directly into the air

• Secondary pollutants– Modified after emission– Ex: smog, acid rain, ozone– Modified by photochemical reactions (activated

by UV radiation)

Primary & Secondary

PRIMARY

• Primary Pollutants:– CO (carbon monoxide)– CO2

– NO (nitrogen oxide)– NO2 (nitrogen dioxide)

– SO2 (sulfur dioxide)

– Particulates– hydrocarbons

Carbon Oxides

– Carbon monoxide (CO) – a highly toxic gas that forms during the incomplete combustion of carbon-containing materials.

– Carbon dioxide (CO2) – a major component of the carbon cycle

• 93% of carbon dioxide (CO2) in the troposphere occurs as a result of the carbon cycle

• 7% of CO2 in the troposphere occurs as a result of human activities (mostly burning fossil fuels)

Nitrogen Oxides (CRITERIA POLLUTANT)

– Nitrogen oxides (NOx) – forms when nitrogen and oxygen gas in air react in automobile engines and coal-burning plants. It can also form from lightning and certain soil bacteria.

• NO reacts with oxygen in the air to form NO2

• NO2 reacts with water vapor in the air to form nitric acid (HNO3) which is a component of acid deposition (Secondary)

• Both NO and NO2 play a role in the formation of smog (Secondary)

Sulfur Oxides

– Sulfur dioxide (SO2) – CRITERIA POLLUTANT!• About one-third of SO2 in the atmosphere occurs

naturally through the sulfur cycle• Two-thirds come from human sources, mostly

combustion of coal containing iron sulfide and from oil refining and smelting of sulfide ores

– FeS2 + O2 Fe2O3 + SO2

• SO2 reacts with water vapor in the air to form sulfuric acid (H2SO4) which is a component of acid deposition (Secondary)

Suspended Particulate Matter (SPM)(CRITERIA POLLUTANT)

– Particulate matter – A variety of solid particles small and light enough to remain suspended in the air

– Natural sources – forest fires, volcanoes, dust storms– Human sources – combustion of various materials

• The most harmful forms of SPM are fine particles (PM-10, with an average diameter < 10 micrometers) and ultrafine particles (PM-2.5).

Volatile organic compounds (VOCs):– Volatile organic compounds – are organic

chemicals that have high enough vapor pressures to vaporize and easily enter the atmosphere (type of hydrocarbon)

– VOCs are widely used in household chemicals• Cleaners, disinfectors, paints, fuels, etc.

– VOCs are also used as industrial solvents• trichlorethylene (TCE), benzene, and vinyl chloride

SECONDARY

• Secondary Pollutants:– SO3 (sulfur trioxide)

– HNO3 (nitric acid)

– H2O2 (hydrogen peroxide)

– O3 (ozone)

– PANs (Peroxyacytyl nitrate; found in smog)– H2SO4 (Sulfuric acid)

Smog = smoke + fog

• Photochemical smog (LA type)– from car emissions reacting with sunlight– strong oxidants; harm respiratory system, damage

crops and trees

Istanbul

• Photochemical smog is a mixture of air pollutants formed by the reaction of NO2 and VOCs under the influence of sunlight.

Sunlight Plus Cars Equals Photochemicals Smog

A Model of How Pollutants That Make Up Photochemicals Are Formed

– Mexico City– Beijing, China– New Delhi, India– Cairo, Egypt– Bangkok, Thailand– Hong Kong– Houston, TX– Los Angeles, CA

Worst Smog Cities in the World

Smog• Sulfurous/Industrial smog

(London type, gray air)– from burning coal, oil– Burning releases sulfur oxides

(SOx), mostly sulfur dioxide (SO2)– Mostly in stagnant air, cloud

cover, high humidity– Worse in less developed

countries with inadequate pollution control

London!

Beijing: after rain………..smoggy

How Pollutants Are Formed from Burning Coal and Oil, Leading to Industrial Smog

Ozone (Add to notes!)• Gaseous Pollutant (in Troposphere!)• Sources:

– Vehicle exhaust– Formed from other pollutants in the presence of

sunlight

• Effects– Lung damage– Eye irritation– Respiratory problems– Smog

Acid Rain• pH < than naturally occurring rain (5.6)• SO2 + water vapor H2SO4

• Coal, power plants

• NOx + water vapor HNO3

• Transportation (cars, trucks, buses)

Acid Disposition Is a Serious Regional Air Pollution Problem

Acid Deposition- Harmful Effects

• Acid deposition causes harm in a number of ways:– Aquatic ecosystems affected– Loss of crops and trees– Leaching of soil nutrients– Human respiratory irritation– Release of toxic metals

• Leached out of the soil and into drinking water sources

– Damage to buildings, statues, and monuments

Natural Capital Degradation: Air Pollution Damage to Trees

Trends in Air Pollution

• Worse in urban and industrialized areas

• Influenced by topography, meteorology, seasons

• Temperature inversions• Worst problem in

Greensboro area: ozone in summer

Temperature Inversions

• Thermal inversion – Warm air moves over cooler air “capping” the atmosphere and trapping air pollutants

• Cities with sunny climate, mountains on multiple sides and an ocean on another are susceptible to inversions

Several Factors Can Decrease or Increase Outdoor Air Pollution

Several Factors Can Decrease or Increase Outdoor Air Pollution

• Heat islands – cities and urban areas can be 2º – 10º warmer than the surrounding areas– Caused because buildings and pavement have replaced trees and

vegetation

• Can increase the likelihood of thermal inversions and increase air pollution, especially the formation of smog

Several Factors Can Decrease or Increase Outdoor Air Pollution

Trends in Air Pollution

• Air quality is better in US; EPA estimates since 1970– Every pollutant is decreasing in abundance except

nitrates, which are constant/increasing (why?)• Air quality worse in developing countries:

– Mexico City, Beijing: air exceeds WHO standards 350 days/year

– Eastern Europe (Soviet Block countries) burned high-Sulfur coal, resulted in forest decline due to acid rain, major human health problems

Science Focus: Detecting Air Pollutants

• Chemical instruments– Aircraft– Air pollutant monitors

• Biological indicators– Lichens (fungus/algae)

• Sensitive to air pollutants• Some are pollutant specific (SO2)

– Peppered Moths• Soot from Industrial Revolution in

England and U.S.• % of light/dark moths changed

Control of Air Pollution

Control of Air Pollution

• Cars (produce Nox, CO, previously Lead)– Reduce automobile numbers and use– Stricter emissions standards and enforcement– Low emissions cars, improve gasoline, modify fuel – Public transportation, car pools– Catalytic converters, remove CO, NOx (cars only)

Control of Air Pollution

• Industry (source of SOx, NOx, PM)– PM: use bag filters

– Electrostatic precipitators

– SOx: Use low sulfur, alternative energy, improve conservation, efficiency

– Use Ca (reacts to make CaSO3)

– NOx: burn at lower temperatures

– Scrubbers

Electrostatic precipitator• Used to attract negatively charged

particles in a smokestack into a collector

• Can remove 99% of larger particulate matter

• Does not remove hazardous ultrafine particles

• Produces toxic dust that must be safely disposed of

• Uses large amounts of electricity

There Are Many Ways to Reduce Outdoor Air Pollution

Wet scrubber• Fine mists of water vapor trap

particulates and convert them to a sludge that is collected and disposed of usually in a landfill

• Can remove 98% of SO2 and larger particulate matter

• Not very effective in removing hazardous fine and ultrafine particles

There Are Many Ways to Reduce Outdoor Air Pollution

Legislation

National Ambient Air Quality Standards (NAAQS)

• sets acceptable concentrations for 6 criteria pollutants that – Outdoor pollutants– Threaten public health/ the environment over

broad areas (nonpoint)– Are emitted in large quantities – CO, Pb, NOx, O3, PM, Sox

Specific Pollutants to Know

• Criteria Pollutants:– Nitrogen oxides– Sulfur dioxide– Lead (Pb)*** (success story!)– Ozone, smog– Particulate matter (PM)– Carbon monoxide– Remember: Natalie Sits Leisurely On Plush

Couches

How do you remember the six outdoor criteria pollutants regulated by the National Ambient Air Quality Standards (NAAQS)?

NOSCLP – A nose clip will save you from air pollution

• Nitrogen oxides • Ozone• Sulfur dioxide • Carbon monoxide• Lead• Particulate matter

Air Quality Index (AQI)

• Measures levels of 5 criteria pollutants (not Pb)

• Forecast of daily air pollution levels

• Purpose: to educate and protect public – focuses on health effects

• Limitations: doesn’t cover chronic or synergistic effects

National Emissions Standards for Hazardous Air Pollutants (NESHAP)

• regulates emissions for pollutants not covered by NAAQS

• for specific substances with known or suspected serious health effects (mutagens, carcinogens, neurotoxins, teratogens)

• Tend to be localized, from point sources• Examples: Ammonia, chlorine, asbestos,

arsenic, mercury, benzene

Clean Air Legislation

• 1970 Clean Air Act established NAAQS and AQI• 1990 amendments

– acid rain – urban smog– HAPs (hazardous air pollutant)– Ozone protection (CFCs) – trade allowances for SOx

• Require older industries and refineries to upgrade their pollution controls

Air Pollution: Indoor

Sources

Worse than outdoor?

• People spend more time indoors • HVAC systems can spread molds and bacteria

if not clean and dry• Indoor air is diarrhea which concentrates

pollutants• Buildings are insulated poorly

• Indoor air pollution usually is a greater threat to human health than outdoor air pollution.– Why?

• According to the EPA, many pollutants in the typical home or office are at least 10 times higher than in outdoor air. The average American spends 90% of their time indoors.

• Who are at greatest risk from indoor air pollution?– Children under 5 and the elderly– Pregnant women– People with respiratory disorders or heart problems– Smokers– Factory workers

Indoor Air Pollution Is a Serious Problem

Human health impacts of IAP• Headache, dizziness, nausea, fatigue; skin, eye,

throat irritation, rash, sinus congestion, shortness of breath, coughing, sneezing, etc.

• Sick Building Syndrome– building has unhealthy levels of air pollutants – Occupants exhibit symptoms which disappear when

they go outside– More common is newer buildings

Ways to control IAP

• Reduce source (example: no smoking)• Improve ventilation and exhaust, use indoor

plants• Clean and maintain HVAC, clean air filters, use

dehumidifiers

• Four most dangerous indoor air pollutants– Tobacco smoke– Radioactive radon-222 gas– Formaldehyde– Very small particles

• Other possible indoor air pollutants:– Biological pollutants – Dust, pollen, airborne spores of molds

and mildews, bacteria and viruses, living organisms and their excrements (E.g., Dust mites and cockroach droppings)

– Chemical pollutants – Fumes from paints, cleaners, carpets, fabrics, pesticide residues, lead particles

Indoor Air Pollution Is a Serious Problem

Environmental Tobacco Smoke (ETS)

• Contains 43 known carcinogens, arsenic, benzene, DDT and more

• Increases incidence of pneumonia, bronchitis, colds, ear infections, asthma attacks in children

• Smoking is tied to 87% of lung cancers

• Smoking is the most preventable cause of premature death in US

Formaldehyde

• Used in manufacturing many products• Outgassed from new furniture, drapes, upholstery, carpets,

wallpaper

Radon• inert, radioactive gas, breakdown product of uranium • enters buildings through cracks, holes, well water or in

bricks • measured in pCi/L (picocuries per liter)

– average indoor level = 1.3 pCi/L– average outdoor level = 0.4 pCi/L– EPA “action level” is 4.0 pCi/L

• Hotspots: Reading Prong in PA, NJ, NY, some areas in NC • Health effects: lung cancer • Reducing Radon: close entry routes; cracks, drains, increase

ventilation

Asbestos• mineral used as building

material, flame retardant• Causes asbestosis, lung

cancers in workers exposed to high levels

• Controversial: Has been banned and removed from schools

• Some people think that the risks have been overstated

Others…

• Legionnaire's Disease (Legionellosis)– pneumonia– outbreak during a American Legion Convention

Philadelphia, 1976, – bacteria spread via HVAC system.

• Indoor pesticide use – Schools are routinely treated, children are especially

susceptible. – Safer to use Integrated Pest Management (IPM)