seasons

•

Air Pollution

Review

• Name the bottom two layers of the atmosphere– Troposphere, stratosphere

• 75-80% of atmosphere’s mass is in the __– Troposphere

• Distinguish between good and bad ozone– good: stratosphere, UV; bad: troposphere, lungs

Pollution Thorpe, Gary S., M.S., (2002). Barron’s How to prepare for the AP Environmental Science Advanced Placement Exam• The term “Smog” (smoke and fog) was first used The term “Smog” (smoke and fog) was first used

in 1905 to describe sulfur dioxide emissionin 1905 to describe sulfur dioxide emission

• In 1952, severe pollution took the lives of 5000 In 1952, severe pollution took the lives of 5000 people in London people in London

• ““It isn’t pollution that’s harming the It isn’t pollution that’s harming the environment. It’s the impurities in our air and environment. It’s the impurities in our air and water that are doing it.” water that are doing it.” FormerFormer U.S. Vice U.S. Vice President Dan QuaylePresident Dan Quayle

www.aqmd.gov/pubinfo/ 97annual.html

• Salt Lake City on a smoggy day

Killer London smog, 1952

• December• Very cold for several

days • People burned more

coal• Sulfur dioxide,

particulates

Deaths during ’52 killer smog

•

London smogs

• • Picadilly circus, London, winter, 1955

• NOON

1948: Air pollution inversion (cool air trapped by warm air above it keeps pollution from dispersing) in Donora, Pennsylvania, kills 20 people and makes 40 percent of the town's 14,000 inhabitants ill.

1952: Sulfur-laden smog covers London and is responsible for 4,000 deaths over a two-week period.

1967: Air Quality Control Act passed by Congress, setting timetables for states to establish their own air quality standards.

1970: Congress passes the Clean Air Act, allowing the newly created Environmental Protection Agency to set national air quality standards. Also allowed states to establish their own stricter standards, which California did.

Clean Air Act 1970• Amendments to an earlier act• ``To put the 1970 amendments in proper context, one needs to look back at

Congress' prior efforts to control air pollution, particularly the Air Quality Act of 1967. That statute authorized the Secretary of Health, Education, and Welfare (who then had chief responsibility for federal environmental protection programs) to designate so-called air quality regions throughout the country; the states were given primary responsibility for adopting and enforcing pollution control standards within those regions.

Some of us involved in the enactment of the 1967 statute had significant doubts as to the viability of the regional approach to air pollution control; after all, air contamination does not stop at neatly defined regional boundaries. Nevertheless, Congress as a whole and American industry were not yet convinced of the need for a national strategy for pollution control; therefore, as a first step, the 1967 statute's regional approach became the law of the land.’’

Paul Rogers, chair of House subcommittee on Health and the environment

Debate on Clean Air Act, 1970

• During House floor debate:– A representative quote a mayor: ``If you want

this town to grow, it has got to stink.’’– A common view then– Similar arguments continue to be made with

respect to efforts to control global warming

Clean Air ActRequires EPA to set National Ambient Air Quality

Standards (NAAQS) for six ``criteria’’ air pollutants

• Ozone

• Sulfur dioxide

• Lead

• Carbon monoxide

• Nitrogen dioxide• Particulate matter

Primary PollutantsPrimary Pollutants

Secondary PollutantsSecondary Pollutants

SourcesSourcesNaturalNatural

StationaryStationary

COCO COCO22

SOSO22 NONO NONO22

Most hydrocarbonsMost hydrocarbons

Most suspendedMost suspendedparticlesparticles

SOSO33

HNOHNO33 HH22SOSO44

HH22OO22 OO33 PANsPANs

MostMost andand saltssaltsNONO33––

MobileMobile

SOSO4422 ––

Major Sources of Primary Pollutants

Stationary Sources• Combustion of fuels for power and heat – Power Plants• Other burning such as Wood & crop burning or forest fires• Industrial/ commercial processes• Solvents and aerosols

Mobile Sources• Highway: cars, trucks, buses and motorcycles• Off-highway: aircraft, boats, locomotives, farm equipment, RVs,

construction machinery, and lawn mowers

Natural air pollution• Who said the following:• "I have flown twice over Mount St. Helens out on our west coast. I'm not a scientist

and I don't know the figures, but I have a suspicion that that one little mountain has probably released more sulfur dioxide into the atmosphere of the world than has been released in the last ten years of automobile driving or things of that kind that people are so concerned about.’’

• "Trees cause more pollution than automobiles do." – RONALD REAGAN

Natural sources

• The facts:– Volcanoes DO emit SO2.

Kilauea much worse than Mount St Helens. MSH probably emits less than cars; Kilauea more (largest SO2 point-source emitter in the US). Volcanoes also put out particles and can cause health and climate effects

– Some air pollution does come from trees, decay. Typically, spread out and not a health risk, unlike anthropogenic sources

Wind, dust particulates

Volcanoes Particulates, SO2, CO2

Forest fires CO2, unburned HC

Vegetation VOCs, pollen

Ocean salt

Human Impact on Atmosphere• Burning Fossil Fuels

• Using Nitrogen fertilizers and burning fossil fuels

• Refining petroleum and burning fossil fuels

• Manufacturing

Adds CO2 and O3 to troposphere

Global Warming Altering Climates Produces Acid Rain Releases NO, NO2, N2O, and NH3 into

troposphere Produces acid rain Releases SO2 into troposphere

Releases toxic heavy metals (Pb, Cd, and As) into troposphere

www.dr4.cnrs.fr/gif-2000/ air/products.html

Criteria Air PollutantsEPA uses six "criteria pollutants" as indicators of air quality

1. Nitrogen Dioxide: NO2

2. Ozone: ground level O3

3. Carbon monoxide: CO

4. Lead: Pb

5. Particulate Matter: PM10 (PM 2.5)

6. Sulfur Dioxide: SO2

• Volatile Organic Compounds: (VOCs)

EPA established for each concentrations above which adverse effects on health may occur

Nitrogen Dioxide (NO2)• Properties: reddish brown gas, formed as fuel

burnt in car, strong oxidizing agent, forms Nitric acid in air

• Effects: acid rain, lung and heart problems, decreased visibility (yellow haze), suppresses plant growth

• Sources: fossil fuels combustion, power plants, forest fires, volcanoes, bacteria in soil

• Class: Nitrogen oxides (NOx) • EPA Standard: 0.053 ppm

Mobile Source Emissions: Nitrogen Oxides

Ozone (O3)

• Properties: colorless, unpleasant odor, major part of photochemical smog

• Effects: lung irritant, damages plants, rubber, fabric, eyes, 0.1 ppm can lower PSN by 50%,

• Sources: Created by sunlight acting on NOx and VOC , photocopiers, cars, industry, gas vapors, chemical solvents, incomplete fuel combustion products

• Class: photochemical oxidants

Ozone (O3)

• 10,000 to 15,000 people in US admitted to hospitals each year due to ozone-related illness

• Children more susceptible– Airways narrower– More time spent outdoors

Mobile Source Emissions: Hydrocarbons – Precursors to

Ozone

Carbon Monoxide (CO)

• Properties: colorless, odorless, heavier than air, 0.0036% of atmosphere

• Effects: binds tighter to Hb than O2, mental functions and visual acuity, even at low levels

• Sources: incomplete combustion of fossil fuels 60 - 95% from auto exhaust

• Class: carbon oxides (CO2, CO)

• EPA Standard: 9 ppm

• 5.5 billion tons enter atmosphere/year

Mobile Source Emissions - CO

Lead (Pb)

• Properties: grayish metal

• Effects: accumulates in tissue; affects kidneys, liver and nervous system (children most susceptible); mental retardation; possible carcinogen; 20% of inner city kids have [high]

• Sources: particulates, smelters, batteries

• Class: toxic or heavy metals

• EPA Standard: 1.5 ug/m3

• 2 million tons enter atmosphere/year

Suspended Particulate Matter (PM10) •Properties: particles suspended in air (<10 um)

•Effects: lung damage, mutagenic, carcinogenic, teratogenic

•Sources: burning coal or diesel, volcanoes, factories, unpaved roads, plowing, lint, pollen, spores, burning fields

•Class: SPM: dust, soot, asbestos, lead, PCBs, dioxins, pesticides

•EPA Standard: 50 ug/m3 (annual mean)

Mobile Source Emissions: Fine Particulate Matter (PM2.5)

Sulfur Dioxide (SO2) • Properties: colorless gas with irritating odor

• Effects: produces acid rain (H2SO4), breathing difficulties, eutrophication due to sulfate formation, lichen and moss are indicators

• Sources: burning high sulfur coal or oil, smelting or metals, paper manufacture

• Class: sulfur oxides

• EPA Standard: 0.3 ppm (annual mean)

• Combines with water and NH4 to increase soil fertility

VOCs (Volatile Organic Compounds)

• Properties: organic compounds (hydrocarbons) that evaporate easily, usually aromatic

• Effects: eye and respiratory irritants; carcinogenic; liver, CNS, or kidney damage; damages plants; lowered visibility due to brown haze; global warming

• Sources: vehicles (largest source), evaporation of solvents or fossil fuels, aerosols, paint thinners, dry cleaning

• Class: HAPs (Hazardous Air Pollutants) – Methane

– Benzene

– Chlorofluorocarbons (CFCs), etc.

• Concentrations indoors up to 1000x outdoors

• 600 million tons of CFCs

Temperature inversion

• Makes effects of air pollutants worse

• Usually: sun warms air at Earth’s surface, which rises and mixes, dispersing pollutants

• Sometimes: layer of warm air above cooler, denser air, which does not rise and mix

• Ordinarily, warm air rises, carrying pollutants with it

• If colder air is under warmer air, the air is stable, and pollution can be trapped

Another kind of temperature inversion

• Air warms up by compression as it flows downslope. Forms a ``lid’’ over colder air. This type of inversion common in Denver, which is to right of the mountains

Acid rain

• Sulfur dioxide and nitrogen oxides react in atmosphere acidic chemicals that can travel long distances and return to earth

• Tall stacks reduce local pollution, but increase regional

Sudbury, Ont. superstack

•

• SEE TEXTBOOK, P. 445 Note: coal-burning plants in AZ, plume to NE

Acid rain impacts

• Erode metal and stone• Acidifies lakes,

leading to fish deaths• Acidifies soil, leaching

plant nutrients

The future of acid rain

• For better– Clean Air Act

amendments of 1990 led to reductions in SO2 and Nox

– Cap-and-trade program

• For worse– U.S. and China have

huge coal reserves

Smog

• Photochemical smog– Air pollutants (VOCs, NOx) react under

influence of sunlight and heat– Form: ground level ozone and other chemicals

that together = smog

• Industrial smog– A mixture of sulfur dioxide, sulfuric acid and

particulates– Often in winter, with coal burning (eg: London)

Industrial smog in China• Bejing• China is home to 20 of

the world’s top 30 most smog-plagued cities

Factors influencing smog formation

• DECREASE

• Local climate: rain and snow wash pollutants out; dry areas more prone

• Winds: mix pollutants or blow them away

• Salt spray from ocean: can remove particulates

• INCREASE• Tall buildings reduce

wind• Hills and mountains• High temperatures

Indoor air pollution

• Often: a GREATER threat to health than outdoor air pollution

• EPA studies:– 11 common pollutants often

2-5x higher indoors

– May be higher in cars in urban areas

– People spend more time indoors

Indoor air pollution

• Biggest problems– Formaldehyde: low levels emitted from many

household products• Furniture, paneling and plywood, insulation

– Radon: natural radioactive gas found in soil• Outdoors, disperses; indoors, may concentrate and

contribute to lung cancer

– Lead, asbestos, carbon monoxide, chloroform