Chapter 19

Air Pollution

When Is a Lichen Like a Canary?• Some lichen species are

sensitive to specific air-polluting chemicals. Ex. Sulfur dioxide

• Good biological indicators – continually absorb air as a source of nourishment.

• Orange crusty – moderate pollution

• Gray-green crusty – high pollution

• Leafy lichens – fairly clean air

Figure 19-1Figure 19-1

BIOLOGY REVIEW

• A LICHEN IS MADE UP OF A ______________ AND AN ALGA.

• NAME 2 OTHER SYMBIOTIC RELATIONSHIPS BESIDES MUTUALISM.

• IN MUTUALISM, WHICH SPECIES BENEFITS?

• WHY COMPARE A LICHEN TO A CANARY?

CASE STUDY ASSIGNMENT

• RESEARCH AND LIST LICHENS (SCIENTIFIC NAME AND COMMON NAME) NATIVE TO THE UNITED STATES (10 MINIMUM)

• EXPLAIN THE CONTROLLED EXPERIMENT YOU WOULD SET UP AND CONDUCT TO DETERMINE THE TYPES AND AMOUNT(S) OF POLLUTION IN VARIOUS AREAS AROUND THE U.S.

• DUE TUESDAY OCTOBER 14 , DO NOT TYPE – WRITE LEGIBLY

STRUCTURE AND SCIENCE OF THE ATMOSPHERE

• Troposphere – • life giver & weather breeder • 11 miles above sea level at

equator• 5 miles above sea level at

poles• Dynamic system: chemical

cycling of many vital nutrients;

• Rising/falling air currents & winds largely responsible for weather & climate;

Figure 19-2Figure 19-2

STRUCTURE AND SCIENCE OF THE ATMOSPHERE

• Troposphere – Air composition:– 78% N2– 21% O2– Water vapor, Argon, CO2,

CH4, O3, N2O, Dust & soot particles

Figure 19-2Figure 19-2

STRUCTURE AND SCIENCE OF THE ATMOSPHERE

• Troposphere• Temperatures decrease with

altitude until the Tropopause (upper boundary) is reached;

• Cold temperatures produce a thermal barrier that prevents mixing of air between the Troposphere & Stratosphere;

• Then temperatures increase with altitude in the Stratosphere

Figure 19-2Figure 19-2

STRUCTURE AND SCIENCE OF THE ATMOSPHERE

• Stratosphere – 11 – 30 miles above sea level

• 78%N2, 21%O2, O3% much higher than in Troposphere

• Contains the ozone layer that shields 95% of UV from earth

• Ozone layer 11 – 19 miles above sea level

• Also prevents much of O2 in Troposphere from being converted to photochemical ozone

Figure 19-2Figure 19-2

FACTS YOU NEED TO KNOW

• OZONE IS PRODUCED WHEN O2 INTERACTS WITH UV RADIATION;

• 3O2 + UV YIELDS 2O3

• GOOD OZONE IS O3

• BAD OZONE IS PHOTOCHEMICAL

• PREFIX PHOTO MEANS LIGHT

• Mesosphere – temperature decreases with increasing altitude (maximum altitude for aircraft) – area for meteors to burn up

• Thermosphere – outer layer – orbiting areas for satellites – UV rays cause ionization (radio waves bounce off here & are returned) – responsible for aurora borealis/australis

AIR POLLUTION

• Primary vs. secondary pollutants• Stationary vs. mobile sources• Natural sources (volcanoes, dust, fires, pollen, salt, VOCs)

Figure 19-3Figure 19-3

National Ambient Air Quality Standards (NAAQS)

• Regulates the following pollutants:• 1) SO2 • 2) SPM (Suspended• Particulate Matter)• 3) Pb• 4) O3• 5) NO2• 6) CO

Major Air Pollutants

• Carbon oxides: – Carbon monoxide (CO) -

highly toxic gas - forms during the incomplete combustion of carbon-containing substances, ex. fossil fuels

CARBON MONOXIDE

• SOURCES INCLUDE: MOTOR VEHICLE EXHAUST, BURNING OF FORESTS/GRASSLANDS, TOBACCO SMOKE, COOKING WITH OPEN FIRES, INEFFICIENT STOVES

• CHRONIC EXPOSURE CAUSES HEART ATTACKS, ASTHAMA, BRONCHITIS, EMPHYSEMA

• HIGH EXPOSURE CAUSES HEADACHE,NAUSEA, DROWSINESS,MENTAL IMPAIRMENT, COLLAPSE, COMA, DEATH

CARBON DIOXIDE

• IS NOT REGULATED UNDER THE U.S. CLEAN AIR ACT;• 93% RESULTS FROM NATURAL CARBON CYCLE• 7% FROM HUMAN ACTIVITIES (BURNING)• S/B REGULATED BECAUSE CO2 IS BEING ADDED TO THE

ATMOSPHERE FASTER THAN C CYCLE CAN REMOVE IT• CONTRIBUTES TO GLOBAL CLIMATE CHANGE

– HEAT EXHAUSTION– DECREASE FOOD SUPPLIES– WATER SHORTAGE– DROUGHT– EXCESSIVE FLOODING

Major Air Pollutants• Nitrogen oxides and nitric acid:

– Nitrogen oxide (NO) - forms when nitrogen and oxygen gas in air react at high-combustion temperatures in automobile engines and coal-burning plants. NO can also form from lightning and certain soil bacteria – cause lung irritation & infections

• NO reacts with air to form NO2 (reddish-brown gas in smog)

• NO is a greenhouse gas (GHG)

• NO2 reacts with water vapor in the air to form nitric acid (HNO3) and nitrate salts (NO3

-) which are components of acid deposition.

• Both play a role in the formation of photochemical smog-mixture of chemicals formed from interaction of sunlight in cities with heavy traffic

Major Air Pollutants• Sulfur dioxide (SO2) and sulfuric

acid:– Two-thirds come from human sources, mostly

combustion (S+ O2 SO2) of sulfur-containing coal and from oil refining and smelting of sulfide ores.

– SO2 in the atmosphere can be converted to sulfuric acid (H2SO4) and sulfate salts (SO4

2-) that return to earth as a component of acid deposition.

– Causes breathing problems & bronchitis.– Irritating odor– All are major components of South Asian Brown

Clouds

Major Air Pollutants

• Suspended particulate matter (SPM):– Consists of a variety of solid particles and liquid droplets small

and light enough to remain suspended in the air (62% from smoke, dust, pollen, soot)

– 38% from coal burning plants (power & industrial), motor vehicles & road construction;

– SPM Toxic Particulates include Pb, Cd, PCBs)

– The most harmful forms of SPM are fine particles (PM-10, with an average diameter < 10 micrometers) and ultrafine particles (PM-2.5) – these are small enough to get to alveoli.

– Causes bronchitis, acid rain, mutations, reproductive problems

Major Air Pollutants• Ozone (O3):

– Is a highly reactive, irritating gas - major component of photochemical smog – reacts with VOCs & NOx’s.

– It can • Cause and aggravate respiratory

illness.

• Decrease resistance to colds/pneumonia

• Can aggravate heart disease.

• Damage plants, rubber in tires, fabrics, and paints.

Major Air Pollutants• Volatile organic

compounds (VOCs):– Most are hydrocarbons emitted by the

leaves of many plants and methane (CH4)– About two thirds of global methane

emissions comes from human sources (rice paddies, landfills, oil/natural gas wells)

– Other VOCs include industrial solvents such as trichlorethylene (TCE), isoprenes (C3H8), terpenes (C10H15), benzene (C6H6), gasoline (C8H18), and vinyl chloride (C2H3Cl)

– LT Exposure – leukemia, blood disorders, immune system damage

Major Air Pollutants

• Radon (Rn):– naturally occurring

radioactive gas found in some types of soil and rock (primarily granite bedrock).

– It can seep into homes and buildings sitting above such deposits through cracks in foundations & through well water.

URBAN OUTDOOR AIR POLLUTION

• Industrial smog (gray-air smog) - mixture of SO2, H2SO4, and a variety of SPM’s emitted mostly by burning coal.

• Sulfur in coal reacts with O2 yielding SO2 yielding H2SO4 + NH3 yielding (NH4)2SO4 (ammonium sulfate)

• (Coal from Eastern U S – bituminous - high in sulfur)• Frequency & severity depends on:• 1) Local climate & topography (bad with hills/mtns)• 2) Population density• 3) Amount of industry• 4) Types of fuels used

South Asia’s Massive Brown Clouds• Caused by coal-burning in China and

India• Covers India, Bangladesh, China’s

industrial heart, parts of Western Pacific Ocean

• 3 KM thick (approx. 2 miles); • Size of continental U S• Contains small particles of dust, smoke,

ash, soot, acidic compounds, toxic metals (Hg, Pb)

South Asia’s Massive Brown Clouds• Problems:

– Reduces photosynthesis– Changes weather patterns– Changes food production due to decreased rainfall in

North and flooding in South – Moves across continents– Moves to West Coast of U S– EPA has determined for LA that 25% of SPM, 77% of soot

and 33% of Hg comes from China

– Satellites show that long-lived air pollution can circle the world in about two weeks;

– Air Pollution Connects Us All.

Sunlight plus Cars Equals Photochemical Smog

• Photochemical smog - mixture of air pollutants formed by the reaction of nitrogen oxides and volatile organic hydrocarbons under the influence of sunlight (Atlanta’s summer smog).

Sunlight plus Cars Equals Photochemical Smog

• Mexico City, L.A., Sydney, Bangkok, Santiago, Sao Paulo & Atlanta all suffer from photochemical smog due to dry, sunny climates with lots of motor vehicles

Figure 19-4Figure 19-4

Factors Influencing Levels of Outdoor Air Pollution

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

chemical reactions. – Ex. SO2+O2 = SO3 + H2O = H2SO4 which falls

out as acid precipitation becoming acid deposition;

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

mountains (promote temperature inversions), and high temperatures (promote photochemical reactions), VOC emissions, Grasshopper Effect, Temperature Inversions;

Temperature Inversions Can Occur in 2 Types of Areas

• Cold, cloudy weather in a valley surrounded by mountains can trap air pollutants (left). (October 1948, Donora, PA Yellow fog)

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

Figure 19-5Figure 19-5

Temperature Inversions

• Subsidence inversion – large mass of warm air floats in at high altitude – floats over the cooler air – no vertical mixing

• Radiation inversion – at night, air near the ground cools faster – usually clears up next day when sun comes out (see this more in valleys in cloudy/cold areas)

ACID DEPOSITION

• Sulfur dioxides, nitrogen oxides, and particulates react in the atmosphere to produce acidic chemicals– Tall smokestacks reduce local air

pollution but increases regional air pollution.

– Prevailing winds can transport primary pollutants, SO2 & NO2 up to 1000 km

ACID DEPOSITION

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

Figure 19-6Figure 19-6

FORMS OF ACID DEPOSITION

• Wet deposition = acidic rain, snow, fog, cloud vapor

• Takes place within 4-14 days of emission

• Dry deposition = solid particles that are acidic

• Takes place within 2-3 days of emission

ACID DEPOSITION

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

Figure 19-7Figure 19-7

ACID DEPOSITION

• RESULTS FROM HUMAN ACTIVITIES THAT DISRUPT THE NATURAL NITROGEN AND SULFUR CYCLES

• BY ADDING EXCESSIVE AMOUNTS OF NITROGEN OXIDES AND SULFUR DIOXIDE TO THE ATMOSPHERE;

ACID DEPOSITION

Figure 19-8Figure 19-8

EFFECTS OF ACID DEPOSITION ON SOILS

• SOILS WITH BASIC COMPOUNDS SUCH AS CALCIUM CARBONATE OR LIMESTONE CAN BUFFER SOME ACID

• AREAS MOST SENSITIVE HAVE THIN, ACIDIC SOIL WITH NO NATURAL BUFFERING OR ALREADY DEPLETED

EASTERN U.S.

• TYPICAL PRECIP IS 10X MORE ACIDIC THAN NATURAL PRECIP

• WHY?• MIDWEST COAL BURNING POWER PLANTS EMISSIONS (W

TO E WINDS)• + AUTO EMISSIONS & OTHER INDUSTRY• SOME MTN TOP FORESTS RECEIVE ACID PRECIP 1000X

THAT OF NORMAL PRECIP

OTHER COUNTRIES

• ACIDIC EMISSIONS FROM UK & GERMANY BLOW S & E INTO SWITZERLAND & AUSTRIA

• AND BLOW N & S INTO NORWAY• ASIA HAS THE WORST ACID PRECIP ESP. CHINA• 70% TOTAL ENERGY FROM BURNING COAL• CHINA IS THE WORLD’S TOP EMITTER OF SO2• DAMAGES CROPS IN CHINA, JAPAN AND N/S

KOREA

THE HARMFUL EFFECTS OF ACID DEPOSITION – AQUATIC ECOSYSTEMS

• Leaches toxic metals, lead and mercury, into lakes used as drinking water source;

• Toxic metals can accumulate in tissues of fish consumed by humans & other animals;

• Hg is transformed to methylmercury & biomagnifies• Few fish can survive in water with ph less than 4.5;• Releases Al+ causes mucus formation on fish, clogging

gills and suffocation• Aerosols in Asian Brown Clouds are pulled into

thunderstorms that dump acid rain into Indian & Pacific Oceans

THE HARMFUL EFFECTS OF ACID DEPOSITION – TERRESTRIAL ECOSYSTEMS

• Soil ph less than 5.1 can harm crops by• Reducing plant productivity & the• Ability of soils to buffer acidic inputs• In forests, Ca and Mg leached from soils (both necessary

nutrients)• In forests, Al+, Pb+, Cd+, Hg+ released into soil, damaging

roots.• Trees are weakened and vulnerable to severe cold, disease,

insects and drought.

ACID DEPOSITION & MOUNTAIN TOP AREAS

• Hardest hit terrestrial areas by acid deposition due to

• Thin soils with little buffering capacity &

• Bathed almost continuously in highly acidic fog and clouds

ACID DEPOSITION• Nutrient leaching

• Heavy metal release

• Weakens trees (evident on mountaintops where pH can be 2.3 on balds)

Figure 19-9Figure 19-9

WHAT ACID DEPOSITION HAS DONE TO THE WORLD’S FORESTS & LAKES

• Has not reduced overall tree growth in US and Canada due to significant reductions in SO2 & NO2

• It has accelerated the leaching of plant nutrients from soils, hindering tree growth

• An additional 80% reduction in SO2 emissions needed in Mid Western US before NE lakes, stream & forests can recover

SOLUTIONS TO ACID DEPOSITION

• Prevention

• Homework – Discuss the many ways to decrease the problem of acid deposition, pages 451 -452.

SOLUTIONS TO ACID DEPOSITION

• FIG. 19-10 PAGE 452• BEST:

– PREVENTION APPROACHES THAT REDUCE OR ELIMINATE EMISSIONS OF SULFUR DIOXIDE, NITROGEN DIOXIDES AND PARTICULATES INCLUDING:

• IMPROVE ENERGY EFFICIENCY• REDUCE COAL USE• INCREASE NATURAL GAS USE• BURN LOW SULFUR COAL• TAX EMISSIONS OF SULFUR DIOXIDES

INDOOR AIR POLLUTION

• IAP = greater threat to human health than outdoor air pollution ( 2-5x higher than outside) - #1 source of cancer risk.

• 17% of US buildings are “sick”• According to the EPA, the four most dangerous

indoor air pollutants in developed countries are:– 1) Tobacco smoke.– 2) Formaldehyde.– 3) Radioactive radon-222 gas.– 4) 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

Asbestos

• Fibrous silicate minerals – was used in brake linings, shingles, water pipes, flooring

• Must be completely sealed or it’s a fibrous dust

• Causes asbestosis, lung cancer, & mesothelioma (cancer of lung’s lining)

Radioactive Radon

• Radon-222 -radioactive gas – produced by decay of uranium 238 – 4 picocurie level = EPA’s recommended max – no safe threshold level

Figure 19-13Figure 19-13

HEALTH EFFECTS OF AIR POLLUTION

• Cancer, asthma, chronic bronchitis, emphysema

Figure 19-14Figure 19-14

HEALTH EFFECTS OF AIR POLLUTION

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

Figure 19-15Figure 19-15

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

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

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

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

Air Pollution is a Big Killer

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

Figure 19-16Figure 19-16

CLEAN AIR ACTS 1970, 1977, 1990 • 1) Regulates SPLONC’s – through NAAQS

• 2) Command & Ctrl Approach – federal gov establishes the regulations, states & cities enforce it

• 3) Primary standards – protect human health• 4) Secondary standards – prevent environmental & property damage• 5) States must develop SIPs – how they will meet CAA reguirements. –

must list all pollutants & estimate quantities

Deficiencies in the Clean Air Act:– The U.S. continues to rely on cleanup rather than

prevention.– The U.S. Congress has failed to increase fuel-

efficiency standards for automobiles (recently changed).

– Regulation of emissions from motorcycles and two-cycle engines remains inadequate.

– There is little or no regulation of air pollution from oceangoing ships in American ports.

Deficiencies in the Clean Air Act:

– Airports are exempt from many air pollution regulations.

– The Act does not regulate the greenhouse gas CO2 (in debate right now)

– The Act has failed to deal seriously with indoor air pollution.

– There is a need for better enforcement of the Clean Air Act.

ATTEMPTS TO IMPROVE AIR QUALITY

• 1) MTBE added to fuels (increases O2 content – makes it burn more completely) (methyl tert-butyl ether)

• 2) RFG – reformulated gas• 3) CAFÉ standards (27.5 for cars, 23.5 for light trucks, SUVs

– 35 mpg in 2020) set by DOT (corporate average fuel economy)

• 4) New diesel engines – decrease emissions by 1/3• 5) Catalytic converters – burn any unburned hydrocarbons in

fuel

Using the Marketplace to Reduce Outdoor Air Pollution

• To help reduce SO2 emissions, the Clean Air Act authorized and emission trading (cap-and-trade) program.– Enables the 110 most polluting

power plants to buy and sell SO2 pollution rights.

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

Ways to Prevent and Control Air Pollution from Coal-burning

Facilities–1) Electrostatic precipitators: are

used to attract negatively charged particles in a smokestack into a collector.

–2) 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.

Electrostatic Precipitator• Can remove 99% of

particulate matter

• Does not remove hazardous ultrafine particles.

• Produces toxic dust that must be safely disposed of.

• Uses large amounts of electricity

Figure 19-18Figure 19-18

Wet Scrubber• Can remove 98% of

SO2 and particulate matter.

• Not very effective in removing hazardous fine and ultrafine particles.

Figure 19-18Figure 19-18

Fig. 19-21, p. 461

What Can You Do?

Indoor Air Pollution

• Test for radon and formaldehyde inside your home and take corrective measures as needed.

• Do not buy furniture and other products containing formaldehyde.

• Remove your shoes before entering your house to reduce inputs of dust, lead, and pesticides.

• Test your house or workplace for asbestos fiber levels and for any crumbling asbestos materials if it was built before 1980.

• Don't live in a pre-1980 house without having its indoor air tested for asbestos and lead.

• Do not store gasoline, solvents, or other volatile hazardous chemicals inside a home or attached garage.

• If you smoke, do it outside or in a closed room vented to the outside.

• Make sure that wood-burning stoves, fireplaces, and kerosene- and gas-burning heaters are properly installed, vented, and maintained.

• Install carbon monoxide detectors in all sleeping areas.

INDOOR AIR POLLUTION

• USING DIAGRAM 19-11, PAGE 453, MAKE A CHART LISTING THE INDOOR AIR POLLUTANT, THE SOURCE AND THE POSSIBLE THREAT TO HUMAN HEALTH;