Environmental Science: Toward a Sustainable Future Richard T. Wright Atmospheric Pollution PPT by Clark E. Adams Chapter 21.

Environmental Science: Toward a Sustainable Future Richard T. Wright

Atmospheric Pollution PPT by Clark E. Adams

Chapter 21

Atmospheric Pollution

Air-pollution essentials Major air pollutants and their sources Impacts of air pollutants: health and

environment Bringing air pollution under control Unresolved issues

Incorrect Assumptions about Air Pollutants

There are threshold levels of tolerable air pollutants

Dilution is the solution to air pollution Air pollutants can be assimilated by nature Air pollutants do not travel Air pollution accidents will not happen

Pollutants and Atmospheric Cleansing

Air pollutants: gases and aerosols in the atmosphere that have harmful effects

Level of air pollution determined by: The amount of pollutants entering the air The amount of space into which the pollutants

dispersed Mechanisms that remove pollutants from the

air

The Hydroxyl Radical: Nature’s Cleanser

The Appearance of Smog

Impacts of Smog: Temperature Inversion

Air Pollution Effects

Adversely affects human health Damages crops and forests Highly corrosive

Major Air Pollutants and Their Sources (see Table 21-1)

Suspended particulate matter

Volatile organic compounds

Carbon monoxide Nitrogen oxides

Sulfur oxides Heavy metals Ozone Air toxics

Major Air Pollutant Sources

Major Air Pollutants: Primary (see next slide)

Primary pollutants derived directly from burning fuels and wastes Particulates Hydrocarbons Carbon monoxide Nitrogen oxides Sulfur dioxides

Major Pollutants: Secondary (see next slide)

Secondary air pollutants derive from reactions that occur between primary pollutants and other atmospheric chemicals Ozone PANs Acids: sulfuric and nitric

Comparison of Growth vs. Emissions

Acid Deposition

pH Scale

Acid precipitation = pH <5.5

pH = measurement of H+ ions in solution

Major Sources of SO2 Emitters

Impacts of Air Pollutants on Human Health

Chronic: gradual deterioration of a variety of physiological functions over a period of years

Acute: life-threatening reactions within a period of hours or days

Carcinogenic: cancer-causing

Impacts of Air Pollutants on Human Health

Chronic example: lead poisoning Acute example: death – Bhopal, India Carcinogenic example: lung cancer

The Respiratory System

Impacts of Air Pollutants on the Environment

Plants Necrotic: kills plant cells Chlorotic: destroys chlorophyll, reducing

photosynthesis Increases susceptibility to disease and pests

Ozone most serious pollutant

Ozone Impact on Crop Yields

Impacts of Air Pollutants on the Environment

Forests Leaching of nutrients Release of aluminum into solution Rapid changes in soil chemistry Reduced growth and diebacks of plants and

animals

Impacts of Air Pollutants on the Environment

Forests Increased plant vulnerability to natural

enemies Increased soil erosion Increased flooding Increased sedimentation of waterways

Impacts of Air Pollutants on the Environment

Materials Loss of color Oxidation Corrosion Decreased real estate values

Effects of Acid Deposition

Alteration of plant and animal reproduction Leaching of other toxic elements, e.g.,

aluminum Eutrophic to oligotrophic conditions Total loss of biota from aquatic

ecosystems Alterations of food chains

Trends in Automobile Emissions

Impact of Buffers on Acid Deposition

Bringing Air Pollution under Control

Clean Air Act identifies most widespread pollutants: e.g., particulates, SO, CO, NO, lead = criteria pollutants

National Ambient Air Quality Standards (NAAQS) set levels that protect environmental and human health

Bringing Air Pollution under Control

NAAQS: also set national ambient air quality standards

National Emission Standards for Hazardous Air Pollutants set national emission standards for hazardous air pollutants

Control Strategies

Command-and-control: regulate air pollution so criteria pollutants remain below primary standard level Lack of enforcement and compliance 37% reduction of air pollutants Forced compliance with state implementation

plan (SIP)

Match Control Strategies on Right with Air Pollutants on Left

Particulates VOCs Automobile

emissions Acid rain

Catalytic converter Reasonably

available control strategy (RACT)

Scrubbers Coal washing

Title IV Clean Air Act 1990

Reduce SO emissions 50% below 1980 levels Improve methods of reducing SO emissions Allow emissions allowances and trading Emissions purchases Reduce NO emissions

Industry’s Response to Title IV

Fuel switching Scrubbers Emissions allowance trading Using low-sulfur coals

Unresolved Issues

Costs versus benefits of air pollution control

Status of “new source” review and enforcement

Improving fuel efficiency – hybrid cars Improving mass transit systems Reducing commuting distances

End of Chapter 21