Air Pollution

Chapter 18

What Is the Nature of the Atmosphere?

The atmosphere is structured in layers, including the troposphere, which supports life, and the stratosphere, which contains the protective ozone layer.

Troposphere – “Weather Breeder”

Troposphere - 75–80% of the earth’s air mass- Closet to the earth's surface- Chemical composition of air-Rising and falling air currents:

weather and climate-Involved in chemical cycling

The Stratosphere Is Our Global Sunscreen

Stratosphere• Similar composition to the troposphere, with 2

exceptions• Much less water

• O3, ozone layer, filters UV

• Location – 11 – 30 miles up

What is Air Pollution and What Are the Major Outdoor Pollution Problems?

Air pollution – presence of chemicals in the atmosphere high enough to harm organisms, ecosystems or materials & to alter climate

Human (Anthropogenic) sources: mostly in industrialized and/or urban areas•Stationary sources – examples include industry and power plants•Mobile sources – examples include motor vehicles

Natural sources•Dust blown by wind•Pollutants from wildfires • and volcanoes•Volatile organics released • by plants •Withdrawing groundwater

Some Pollutants in the Atmosphere Combine to Form Other Pollutants

Primary pollutants – released directly into atmosphere

Secondary pollutants – formed by chemical reactions in air

What Are the Major Outdoor Air Pollutants?

Carbon oxides • Carbon monoxide (CO)

• Carbon dioxide (CO2)

• Sources - incomplete combustion of carbon-containing materials

• Human health and environmental impact

CO reduces ability of blood to transport O2

CO2 Do you need to ask? ;-)

Primary Pollutant

What Are the Major Outdoor Air Pollutants?

Nitrogen oxides (NO) and nitric acid (HNO3)

• Sources – automobile engines & coal burning power plants

• Human health and environmental impact – greenhouse gas, acid deposition, irritation to eyes, nose, aggravated asthma, etc

• Photochemical smog (makes harmful O3) – more later

Sulfur dioxide (SO2) and sulfuric acid (H2SO4)

• Sources – coal burning power plants & smelting• Human health and environmental impact – acid

deposition

What Are the Major Outdoor Air Pollutants?

Particulates• Suspended particulate matter (SPM)

• Sources – natural sources, plowed fields, construction, unpaved roads, tobacco smoke, coal burning power plants, cars

• Human health and environmental impact –

Irritate nose, throat, aggravate asthma, some can accumulate in body (lead, PCB’s)

What Are the Major Outdoor Air Pollutants?

Ozone (O3)

• Sources - photochemical smog• Human and environmental impact – same as

others, also damages plants, rubber in tires, etc.

Volatile organic compounds (VOCs)• Hydrocarbons, terpenes, methane• Sources – natural sources, landfills, solvents, rice

paddies, natural gas wells, etc.• Human and environmental impact – greenhouse

gas (CH4), damage plants, can cause cancer

Burning Coal Produces Industrial Smog

Chemical composition of industrial smog (grey)

Reduction of this smog in urban cities of the United States

China and smog• Human deaths

Sunlight Plus Cars Equals Photochemical Smog

Photochemical Smog• Chemical composition• Sources

VOCs + NO2 + Heat +

Sunlight yields • Ground level O3 and other

photochemical oxidants• Aldehydes• Other secondary pollutants

Human health and environmental impact

A Model of How Pollutants That Make Up Photochemicals Are Formed

Several Factors Can Decrease or Increase Outdoor Air Pollution

Outdoor air pollution may be decreased by• Settling of particles due to gravity• Rain and snow• Salty sea spray from the ocean• Winds • Chemical reactions

Outdoor air pollution may be increased by• Urban buildings• Hills and mountains• High temperatures• Emissions of VOCs from certain trees and plants • Grasshopper effect• Temperature inversions

A Temperature Inversion

What Is Acid Deposition and Why Is It a Problem?

Acid deposition is caused mainly by coal-burning power plant and motor vehicle emissions, and in some regions, threatens human health, aquatic life and ecosystems, forests, and human-built structures.

Acid Disposition Is a Serious Regional Air Pollution Problem

Acid deposition, acid rain• Formation• Local versus regional problems• Effects of prevailing winds• Buffers• Where is the worst acid deposition?

Natural Capital Degradation: Acid Deposition, Acid Rain

Current and Possible Future Acid Rain Problem Areas

Acid Deposition Has a Number of Harmful Effects

Human respiratory disorders

Aquatic ecosystems affected

Release of toxic metals Leaching of soil

nutrients Loss of crops and trees Damage to buildings,

statues, and monuments

Solutions: Acid Deposition, Prevention and Cleanup

What Are the Major Indoor Air Pollution Problems?

The most threatening indoor air pollutants are smoke and soot from wood and coal cooking fires (a hazard found mostly in developing countries) and chemicals used in building materials and products.

Developing countries• Indoor burning• Poor suffer the greatest risk

Developed countries• Indoor air pollution is greater than outdoor air

pollution!!! WHY????

Indoor Air Pollution Is a Serious Problem

You asked WHY????....• 11 of the common air pollutants higher inside than outside• Greater in vehicles than outside• Health risks magnified: people spend 70–98% of their time is

indoors

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

Indoor Air Pollution Is a Serious Problem

Four most dangerous indoor air pollutants• Tobacco smoke• Formaldehyde• Radioactive radon-222

gas• Very small particles

Sources of these pollutants

Human health risks

Indoor Air Pollution Is a Serious Problem

Other possible indoor air pollutants• Pesticide residue• Pb particles• Living organisms and their

excrements• E.g., Dust mites and

cockroach droppings

• Airborne spores of molds and mildews

Sick-building syndrome – Let’s watch TWC - SICK BUILDINGS!

Science: Sources and Paths of Entry for Indoor Radon-222 Gas

What Are the Health Effects of Air Pollution?

Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer, heart attack, and stroke.

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

Respiratory system protection from air pollutants• Role of cilia, mucus, sneezing, and coughing

Effect of smoking and prolonged air pollution exposure• Chronic bronchitis• Emphysema

Normal Human Lungs and the Lungs of a Person Who Died of Emphysema

Air Pollution Is a Big Killer

3 Million deaths per year world-wide• Mostly in Asia• Main causes

EPA: proposed stricter emission standards for diesel-powered vehicles

Link between international trade and air pollution• Cargo ships and pollution

Premature Deaths from Air Pollution in the U.S.

How Should We Deal with Air Pollution?

Legal, economic, and technological tools can help to clean up air pollution, but much greater emphasis should be focused on preventing air pollution. - SOUND FAMILIAR???

Laws and Regulations Can Reduce Outdoor Air Pollution

United States• Clean Air Acts: 1970, 1977, and 1990

EPA • National ambient air quality standards (NAAQs)

for 6 outdoor criteria pollutants• National emission standards for 188 hazardous

air pollutants (HAPs)• Toxic Release Inventory (TRI)

Laws and Regulations Can Reduce Outdoor Air Pollution

Good news in U.S.• Decrease in emissions• Use of low-sulfur diesel fuel• Cuts pollution

Developing countries• More air pollution

We Can Use the Marketplace to Reduce Outdoor Air Pollution

Emission trading or cap-and-trade program• Mixed reactions to program

• SO2 emissions down significantly

• NO2 will be tried in the future

Solutions: Stationary Source Air Pollution

Solutions: Motor Vehicle Air Pollution, Prevention and Cleanup

Solutions: Indoor Pollution, Prevention and Cleanup or Dilution