Chapter 7 Outline
A. Urban Air Quality
1. The quality of urban air is measured in terms of six common air pollutants: total suspended particulates, sulfur dioxide, carbon monoxide, nitrogen dioxide, ozone, and lead.
2. Concern about urban air quality stems from the adverse effects that pollution has on human health, crops and plants, property, safety, and visibility.
B. Acid Rain
1. Acid rain has its chemical origin in compounds formed principally from sulfur dioxide emitted from electrical generating plants. These highly acidic compounds fall to the earth as a part of natural precipitation.
2. Acid rain affects the ability of lakes and streams to sustain aquatic life, the growth and mortality rate of forests, and human health.
C. Global Warming
1. Global warming refers to the increased warming of the planet caused by an increase in the emission of greenhouse gases such as carbon dioxide.
2. Global warming could threaten lives and coastal properties by causing an increase in ocean levels and could affect the location of the world's croplands and forests by altering weather patterns.
D. Ozone Depletion
1. Ozone (when present in the stratosphere) is a gas that protects the earth from harmful solar ultraviolet radiation.
2. Emissions such as chlorofluorocarbons enter the stratosphere and destroy ozone while other emissions such as carbon dioxide and methane increase the atmospheric concentration of ozone.
3. The net effect of these emissions is not known with certainty; however, there are indications that significant decreases in ozone have occurred in some pans of the earth's atmosphere, and that further decreases could occur if the use of chlorofluorocarbons is not slowed.
E. Hazardous Air Pollutants
1. There are hundreds, perhaps thousands, of toxic substances that may be transported by the air.
2. These pollutants have been linked to central nervous system damage and cancer in humans.
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