Air PollutionAir Pollution

IntroductionIntroduction

Currently only two real Currently only two real problematic classes of problematic classes of pollutantspollutants– Non-point source agricultural pollutionNon-point source agricultural pollution– Air qualityAir quality

Difficult to control because air flows in Difficult to control because air flows in all directions (air shed)all directions (air shed)

Difficult to perform bioassayDifficult to perform bioassay Easier to control front end (decrease Easier to control front end (decrease

generation of polluted air) than back generation of polluted air) than back end (clean up polluted air)end (clean up polluted air)

Like water pollution, originates in one Like water pollution, originates in one place, impact another place (unlike place, impact another place (unlike soil pollution). soil pollution).

Most air pollution due to use of E.Most air pollution due to use of E.

Sources of all air pollutantsmeasured in California*

(Hydrocarbons, Carbon Monoxide, Oxides of Nitrogen, Oxides of Sulfur and Particulate Matter)

Source: California Department of Consumer Affairs, Bureau of Automotive Repair

Residential fuel combustion, farming operations, construction, road dust, wind-blown dust,

Major Sources of Air Pollution

Regulations – Clean Air ActRegulations – Clean Air Act Based on impact over a large area but low Based on impact over a large area but low

impact over any one areaimpact over any one area

A.A. Goal – maintain air quality to protect Goal – maintain air quality to protect human health and welfare (= environment)human health and welfare (= environment)

1. Two stage protection scheme1. Two stage protection schemea. Human health at worka. Human health at work

b. Widespread environmental controlsb. Widespread environmental controls

2. Two primary sources of air pollution 2. Two primary sources of air pollution (complex problem)(complex problem) a. smoke stacks (power plants, manufacturing)a. smoke stacks (power plants, manufacturing) b. mobile sources (auto’s b. mobile sources (auto’s California acid rain) California acid rain)

note: NE corridor/Los Angeles = 70% of problemnote: NE corridor/Los Angeles = 70% of problem

Regulations – Clean Air Act (con’t)Regulations – Clean Air Act (con’t)B. Policy – maintain “safe” outdoor concentrations of B. Policy – maintain “safe” outdoor concentrations of

pollutantspollutantshazard = exposure X effecthazard = exposure X effect

/ \ \ / \ \ conc. x duration LCconc. x duration LC50, 50, etcetc

C. StrategiesC. Strategies1. Regional air quality plan – if pollution levels go up 1. Regional air quality plan – if pollution levels go up deny new stack permits and/or alter flow of deny new stack permits and/or alter flow of transportation transportation

2. Emission control standards - reduce air pollution 2. Emission control standards - reduce air pollution using Best Available Control Technology (BACT)using Best Available Control Technology (BACT)

Regulations – Clean Air Act (con’t)Regulations – Clean Air Act (con’t) BACTBACT

- Front end controlFront end control- Compromise between function and cost effectiveness - Compromise between function and cost effectiveness -

zero emissions possible but too expensivezero emissions possible but too expensive A.A. BACT for auto’s (mobile source control)BACT for auto’s (mobile source control)

- emission control devices (eg catalytic converter) ~ $700 - emission control devices (eg catalytic converter) ~ $700 each because platinum (most expensive precious metal)each because platinum (most expensive precious metal)- mileage standards (fleet mileage goals - mileage standards (fleet mileage goals never reached) never reached)

Note: gas was cheap so no incentive (abandoned by Reagan, Note: gas was cheap so no incentive (abandoned by Reagan, Bush Sr, most recently Bush Jr Bush Sr, most recently Bush Jr wants us to “conserve”). wants us to “conserve”). Now gas is not cheap, and US is major contributor to global Now gas is not cheap, and US is major contributor to global COCO22 increase increase

B.B. BACT for stationary sources (smokestacks, dry cleaning)BACT for stationary sources (smokestacks, dry cleaning)- sulfur scrubbers - sulfur scrubbers expensive expensive so try to use low sulfur coal so try to use low sulfur coal (S is high in eastern coal, low in western coal(S is high in eastern coal, low in western coal

Examples of reduction in air pollution after Examples of reduction in air pollution after passage of Clean Air Actpassage of Clean Air Act

Some air pollution is not regulatedSome air pollution is not regulated

Wishful

thinking

Photo by R. Grippo

More unregulated air pollution - burning rice stubble in Poinsett Co., Arkansas

Photo by R. Grippo

Air pollution in India

Policeman directing traffic in India

Photo by J. Farris

Major Air PollutantsMajor Air Pollutants- mostly coal-plant generated- mostly coal-plant generated

A.A. Suspended particulatesSuspended particulates

- Most common, oldest problem addressed- Most common, oldest problem addressed1. Trace rock from burning pulverized coal (unburnable residues)1. Trace rock from burning pulverized coal (unburnable residues)

2. Fly ash from coal (contains Cd, Cu, Pb, Se, As, Hg) has high 2. Fly ash from coal (contains Cd, Cu, Pb, Se, As, Hg) has high volume volume control by electrostatic precipitators control by electrostatic precipitators

3.3. Carbon/soot from dieselCarbon/soot from diesel

B.B. GassesGasses1.1. SOSO22

- respiratory inhibitor- respiratory inhibitor

- plant leaf injury- plant leaf injury

- decreases N fixation in bacteria- decreases N fixation in bacteria

- oxidizes to SO- oxidizes to SO33 (sulfur trioxide) (sulfur trioxide) H H22SOSO44

B. Gasses (con’t)B. Gasses (con’t)2. 2. OxidantsOxidants (O (O3 3 ))

- - in atmosphere in atmosphere not enough not enough- at ground level - at ground level too much too much

comes from hydrocarbons comes from hydrocarbons (gasoline) + O(gasoline) + O2 2 = O= O33

- also a respiratory aggravator- also a respiratory aggravator- leaches nutrients from soil - leaches nutrients from soil

lower primary productivity lower primary productivity less carbon fixed less carbon fixed increase increase greenhouse effectgreenhouse effect

3. 3. Nitrogen oxidesNitrogen oxides (NOx (NOx )) - N- N22O nitric acid – comes from atm O nitric acid – comes from atm

N (atm = 80% nitrogen)N (atm = 80% nitrogen) - NO- NO22 nitrous oxide (ha, ha!) nitrous oxide (ha, ha!) - respiratory aggravator - respiratory aggravator

- decreases soil pH - decreases soil pH reduces soil reduces soil micronutrient availability to micronutrient availability to plantsplants

- NO- NO2 2 + H+ H22O = HNOO = HNO3 3 = brown haze = brown haze = smog= smog

Photo courtesy U.S. EPA

B. Gasses (con’t)B. Gasses (con’t)4. Carbon oxides 4. Carbon oxides

- CO monox - CO monox competes with O competes with O2 2 binding on hemoglobin binding on hemoglobin (affinity is 200X O(affinity is 200X O2 2 ))- CO- CO2 2 dioxide = greenhouse effectdioxide = greenhouse effect

Minor Gaseous Air PollutantsMinor Gaseous Air Pollutants

Low in direct effects, high in indirect effectsLow in direct effects, high in indirect effects1.1. CFC’s (Freon)CFC’s (Freon)

– Principal refrigerant (a/c, refrigerators)Principal refrigerant (a/c, refrigerators)– Catalyze destruction of ozoneCatalyze destruction of ozone– Ozone forms protective layer around earth Ozone forms protective layer around earth partially blocks UV partially blocks UV– Montreal Accord (1990) – supposed to phase out CFC’s by 2000 Montreal Accord (1990) – supposed to phase out CFC’s by 2000

(not completely done yet)(not completely done yet)

2.2. HalonHalon– Related to CFCRelated to CFC– Used in fire extinguishersUsed in fire extinguishers

3.3. Carbon tetrachloride and MethychloroformCarbon tetrachloride and Methychloroform– Dry cleaner solventsDry cleaner solvents– Manufacturing processesManufacturing processes

All above compounds catalyze the destruction of ozoneRecall: catalyzers participate in a reaction but are not

consumed hang around a long time (1/2 life of several years) and continue to reduce ozone

Therefore, if stopped using now good effects would take many years to appear

Ozone Depletion Capacity of Ozone Depletion Capacity of Commonly Commonly Used ChemicalsUsed Chemicals

CFC-11CFC-11 76 76 2626CFC-12CFC-12 139139 4545CFC-113CFC-113 92 92 1212

HalonHalon 1211 1211 12 1 12 1Halon 1301Halon 1301 101 101 4 4

Carbon Carbon tetrachloridetetrachloride 67 67 8 8__________________________________________________________________________________

Chemical Atmospheric Share of Contribution Lifetime (yrs) to Depletion (%)

Characteristics of Characteristics of Greenhouse GassesGreenhouse Gasses

346346 1.65 0.31 0.02 0.0002 0.00032 1.65 0.31 0.02 0.0002 0.00032

1 32 150 2000 14,000 17,000 1 32 150 2000 14,000 17,000

_______________________________________________ _______________________________________________

CO2 CH4 N2O O3 CFC-11 CFC-12

Atm contribution

Potential GH effect

Note: Up to 1970 CO2 dominated by 1980 dominance decreased by 2020 other gasses dominate. Result in predicted increase of 0.5º to 3º C

Indoor Air PollutantsIndoor Air Pollutants

Includes SOIncludes SO22, NOx, CO, CO, NOx, CO, CO22 (coal furnace, (coal furnace,

kerosene heater especially if burn outkerosene heater especially if burn out Formaldehyde Formaldehyde

– Common constituent of building materialCommon constituent of building material– Many health effects (humans very sensitiveMany health effects (humans very sensitive

Respiratory aggravatorRespiratory aggravator Potential carcinogenPotential carcinogen ““sick building syndrome” – formaldehyde volatilizes from sick building syndrome” – formaldehyde volatilizes from

building mat’l (including adhesives) building mat’l (including adhesives) trapped inside because trapped inside because buildings are airtight to increase E. efficiency buildings are airtight to increase E. efficiency people get sick people get sick

Non-industrial, non-regulated sources of in-door air pollution

Source: AirAdvice, Inc.

Summary of Major Air PollutantsSummary of Major Air Pollutants

Burning fossil fuels = air pollutionBurning fossil fuels = air pollution Coal Coal sulfur sulfur acid rain acid rain Cars Cars NOx - NOx - “ “ , haze “ “ , haze

Approximately 10,000,000 premature Approximately 10,000,000 premature deaths/year world-wide are attributable to deaths/year world-wide are attributable to stationary and mobile air pollution sourcesstationary and mobile air pollution sources

The least lethal form of energy production

Sharon Harris nuclear power plant, NC

Photo by R. Grippo