Secondary Secondary PollutantsPollutants

Smog, Acid Deposition, Smog, Acid Deposition, Indoor and Outdoor Air Indoor and Outdoor Air

PollutionPollution

Questions for TodayQuestions for Today

1.1. What is Smog?What is Smog?

2.2. What is Acid Deposition and it’s effect on What is Acid Deposition and it’s effect on the environment?the environment?

3.3. What are sources for Indoor Air Pollution?What are sources for Indoor Air Pollution?

4.4. What are the methods to preventing Air What are the methods to preventing Air Pollution?Pollution?

URBAN OUTDOOR AIR URBAN OUTDOOR AIR POLLUTIONPOLLUTION

Industrial smog is a mixture of sulfur dioxide, Industrial smog is a mixture of sulfur dioxide, droplets of sulfuric acid, and a variety of droplets of sulfuric acid, and a variety of suspended solid particles emitted mostly by suspended solid particles emitted mostly by burning coal.burning coal.– In most developed countries where coal and In most developed countries where coal and

heavy oil is burned, industrial smog is not a heavy oil is burned, industrial smog is not a problem due to reasonably good pollution problem due to reasonably good pollution control or with tall smokestacks that transfer the control or with tall smokestacks that transfer the pollutant to rural areas.pollutant to rural areas.

Sunlight plus Cars Equals Sunlight plus Cars Equals Photochemical SmogPhotochemical Smog

Photochemical smog is a mixture of air Photochemical smog is a mixture of air pollutants formed by the reaction of nitrogen pollutants formed by the reaction of nitrogen oxides and volatile organic hydrocarbons oxides and volatile organic hydrocarbons under the influence of sunlight.under the influence of sunlight.

Sunlight plus Cars Equals Sunlight plus Cars Equals Photochemical SmogPhotochemical Smog

Mexico City is one Mexico City is one of the many cities of the many cities in sunny, warm, dry in sunny, warm, dry climates with many climates with many motor vehicles that motor vehicles that suffer from suffer from photochemical photochemical smog.smog.

Figure 19-4Figure 19-4

Factors Influencing Levels of Factors Influencing Levels of Outdoor Air PollutionOutdoor Air Pollution

Outdoor air pollution can be reduced by:Outdoor air pollution can be reduced by:– settling out, precipitation, sea spray, winds, and settling out, precipitation, sea spray, winds, and

chemical reactions. chemical reactions.

Outdoor air pollution can be increased by:Outdoor air pollution can be increased by:– urban buildings (slow wind dispersal of urban buildings (slow wind dispersal of

pollutants), mountains (promote temperature pollutants), mountains (promote temperature inversions), and high temperatures (promote inversions), and high temperatures (promote photochemical reactions).photochemical reactions).

Temperature InversionsTemperature Inversions

Cold, cloudy weather in a valley surrounded by Cold, cloudy weather in a valley surrounded by mountains can trap air pollutants (left).mountains can trap air pollutants (left).

Areas with sunny climate, light winds, mountains Areas with sunny climate, light winds, mountains on three sides and an ocean on the other (right) on three sides and an ocean on the other (right) are susceptible to inversions.are susceptible to inversions.

Figure 19-5Figure 19-5

Fig. 19-5, p. 447

Warmer air Descending warm air mass

Inversion layer Inversion layer

Sea breezeIncreasing altitude

Decreasing temperature

ACID DEPOSITIONACID DEPOSITION Sulfur dioxides, nitrogen oxides, and Sulfur dioxides, nitrogen oxides, and

particulates can react in the atmosphere to particulates can react in the atmosphere to produce acidic chemicals that can travel produce acidic chemicals that can travel long distances before returning to the long distances before returning to the earth’s surface.earth’s surface.– Tall smokestacks reduce local air pollution but Tall smokestacks reduce local air pollution but

can increase regional air pollution.can increase regional air pollution.

ACID DEPOSITIONACID DEPOSITION

Acid deposition consists of rain, snow, Acid deposition consists of rain, snow, dust, or gas with a pH lower than 5.6.dust, or gas with a pH lower than 5.6.

Figure 19-6Figure 19-6

ACID DEPOSITIONACID DEPOSITION

pH measurements in relation to major coal-pH measurements in relation to major coal-burning and industrial plants.burning and industrial plants.

Figure 19-7Figure 19-7

ACID DEPOSITIONACID DEPOSITION Acid deposition contributes to chronic Acid deposition contributes to chronic

respiratory disease and can leach toxic respiratory disease and can leach toxic metals (such as lead and mercury) from metals (such as lead and mercury) from soils and rocks into acidic lakes used as soils and rocks into acidic lakes used as sources for drinking water.sources for drinking water.

ACID DEPOSITIONACID DEPOSITION

Figure 19-8Figure 19-8

ACID DEPOSITIONACID DEPOSITION Air pollution is Air pollution is

one of several one of several interacting interacting stresses that stresses that can damage, can damage, weaken, or kill weaken, or kill trees and pollute trees and pollute surface and surface and groundwater.groundwater.

Figure 19-9Figure 19-9

Fig. 19-9, p. 451

Emissions

SO2 NOxAcid deposition

H2O2 O3

Others

Direct damage to leaves & bark

Reduced photo-synthesis and growth

Susceptibility to drought, extreme cold, insects, mosses, & disease organisms

Soil acidification

Tree death

Leaching

of soil nutrients

Release of toxic metal ions

Root damage

Reduced nutrient & water uptakeAcids

Lake

Groundwater

PANs

Fig. 19-10, p. 452

Solutions

Acid Deposition

Prevention Cleanup

Reduce air pollution by improving energy efficiency

Add lime to neutralize acidified lakes

Reduce coal use

Add phosphate fertilizer to neutralize acidified lakes

Increase natural gas use

Increase use of renewable energy resources

Burn low-sulfur coal

Remove SO2 particulates & NOx from smokestack gases

Remove NOx from motor vehicular exhaust

Tax emissions of SO2

INDOOR AIR POLLUTIONINDOOR AIR POLLUTION Indoor air pollution usually is a greater threat Indoor air pollution usually is a greater threat

to human health than outdoor air pollution.to human health than outdoor air pollution. According to the EPA, the four most According to the EPA, the four most

dangerous indoor air pollutants in developed dangerous indoor air pollutants in developed countries are:countries are:– Tobacco smoke.Tobacco smoke.– Formaldehyde.Formaldehyde.– Radioactive radon-222 gas.Radioactive radon-222 gas.– Very small fine and ultrafine particles.Very small fine and ultrafine particles.

Chloroform

Benzo--pyrene

Styrene

Radon-222

Methylene Chloride

Tobacco Smoke

Carbon Monoxide

Asbestos

Nitrogen Oxides

1, 1, 1-Trichloroethane

Particulates

FormaldehydeTetrachloroethylene

Para-dichlorobenzene

Fig. 19-11, p. 453

INDOOR AIR POLLUTIONINDOOR AIR POLLUTION Household dust mites Household dust mites

that feed on human skin that feed on human skin and dust, live in and dust, live in materials such as materials such as bedding and furniture bedding and furniture fabrics.fabrics.– Can cause asthma Can cause asthma

attacks and allergic attacks and allergic reactions in some people.reactions in some people.

Figure 19-12Figure 19-12

HEALTH EFFECTS OF AIR HEALTH EFFECTS OF AIR POLLUTIONPOLLUTION

Normal human lungs (left) and the lungs of Normal human lungs (left) and the lungs of a person who died of emphysema (right).a person who died of emphysema (right).

Figure 19-15Figure 19-15

Air Pollution is a Big KillerAir Pollution is a Big Killer Each year, air pollution prematurely kills Each year, air pollution prematurely kills

about 3 million people, mostly from indoor about 3 million people, mostly from indoor air pollution in developing countries.air pollution in developing countries.– In the U.S., the EPA estimates that annual In the U.S., the EPA estimates that annual

deaths related to indoor and outdoor air deaths related to indoor and outdoor air pollution range from 150,000 to 350,000.pollution range from 150,000 to 350,000.

– According to the EPA, each year more than According to the EPA, each year more than 125,000 Americans get cancer from breathing 125,000 Americans get cancer from breathing diesel fumes.diesel fumes.

Air Pollution is a Big KillerAir Pollution is a Big Killer

Spatial distribution of premature deaths Spatial distribution of premature deaths from air pollution in the United States.from air pollution in the United States.

Figure 19-16Figure 19-16

PREVENTING AND REDUCING PREVENTING AND REDUCING AIR POLLUTIONAIR POLLUTION

The Clean Air Acts in the United States The Clean Air Acts in the United States have greatly reduced outdoor air pollution have greatly reduced outdoor air pollution from six major pollutants:from six major pollutants:– Carbon monoxideCarbon monoxide– Nitrogen oxidesNitrogen oxides– Sulfur dioxidesSulfur dioxides– Suspended particulate matter (less than PM-10)Suspended particulate matter (less than PM-10)

Using the Marketplace to Reduce Using the Marketplace to Reduce Outdoor Air PollutionOutdoor Air Pollution

To help reduce SOTo help reduce SO22 emissions, the Clean Air Act emissions, the Clean Air Act

authorized an emission trading (cap-and-trade) authorized an emission trading (cap-and-trade) program.program.– Enables the 110 most polluting power plants to buy and Enables the 110 most polluting power plants to buy and

sell SOsell SO22 pollution rights. pollution rights.

– Between 1990-2002, the emission trading system Between 1990-2002, the emission trading system reduced emissions.reduced emissions.

– In 2002, the EPA reported the cap-and-trade system In 2002, the EPA reported the cap-and-trade system produced less emission reductions than were projected.produced less emission reductions than were projected.

Solutions: Solutions: Reducing Outdoor Air PollutionReducing Outdoor Air Pollution

There are a of ways to prevent and control There are a of ways to prevent and control air pollution from coal-burning facilities.air pollution from coal-burning facilities.– Electrostatic precipitatorElectrostatic precipitator: are used to attract : are used to attract

negatively charged particles in a smokestack negatively charged particles in a smokestack into a collector.into a collector.

– Wet scrubberWet scrubber: fine mists of water vapor trap : fine mists of water vapor trap particulates and convert them to a sludge that is particulates and convert them to a sludge that is collected and disposed of usually in a landfill.collected and disposed of usually in a landfill.

Solutions: Solutions: Reducing Outdoor Air PollutionReducing Outdoor Air Pollution

There are a # of ways to prevent and control There are a # of ways to prevent and control air pollution from motor vehicles.air pollution from motor vehicles.– Because of the Clean Air Act, a new car today Because of the Clean Air Act, a new car today

in the U.S. emits 75% less pollution than did in the U.S. emits 75% less pollution than did pre-1970 cars.pre-1970 cars.

– There is and increase in motor vehicle use in There is and increase in motor vehicle use in developing countries and many have no developing countries and many have no pollution control devices and burn leaded pollution control devices and burn leaded gasoline.gasoline.

Fig. 19-19, p. 460

Solutions

Motor Vehicle Air Pollution

Prevention Cleanup

Emission control devices

Mass transit

Bicycles and walking

Less polluting engines

Less polluting fuels

Improve fuel efficiency

Car exhaust inspections twice a year

Get older, polluting cars off the road

Give buyers large tax write-offs or rebates for buying low-polluting, energy efficient vehicles

Stricter emission standards

Indoor Air PollutionIndoor Air Pollution Little effort has been devoted to reducing Little effort has been devoted to reducing

indoor air pollution even though it poses a indoor air pollution even though it poses a much greater threat to human health than much greater threat to human health than outdoor air pollution.outdoor air pollution.

Environmental and health scientists call for Environmental and health scientists call for us to focus on preventing air pollution us to focus on preventing air pollution (especially indoor) in developing countries.(especially indoor) in developing countries.

Fig. 19-20, p. 461

Solutions

Indoor Air Pollution

Prevention

Cover ceiling tiles & lining of AC ducts to prevent release of mineral fibers

Use adjustable fresh air vents for work spaces

Increase intake of outside airBan smoking or limit it to well ventilated areas

Change air more frequently

Set stricter formaldehyde emissions standards for carpet, furniture, and building materials

Circulate a building’s air through rooftop green houses

Prevent radon infiltration Use exhaust hoods for stoves and appliances burning natural gasUse office machines in well

ventilated areas

Use less polluting substitutes for harmful cleaning agents, paints, and other products

Install efficient chimneys for wood-burning stoves

Cleanup or Dilution