CHAPTER 21 - CHAPTER 21 ATMOSPHERIC POLLUTION I. Air...

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CHAPTER 21 ATMOSPHERIC POLLUTION I. Air Pollution A. What Is It? 1. Air pollutants consist of chemicals in the atmosphere that have harmful effects on living organisms and inanimate objects. B. Why Do We Care? 1. We inhale 20,000 liters of air each day a. Causes 150,000 premature deaths in the world each year (53,000 in the United States); aggravates other disease b. Three categories of health impact: · Acute: pollutants bring on life-threatening reactions within a period of hours or days; causes headache, nausea, and eye and throat irritation; aggravate preexisting respiratory conditions such as asthma and emphysema · Chronic: pollutants cause gradual deterioration of health over many years, and exposures are relatively low · Carcinogenic: some pollutants are suspected or known human carcinogens. Benzene, a common component of air pollution, is known as human carcinogen c. U.S. human health costs from outdoor air pollution range from $40 to $50 billion per year (CDC). 2. Damage to Plants
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a. Agriculture: crop loss estimated to be about $5 billion per year b. Forests: significant damage to Jeffrey and Ponderosa Pine along entire Western slope of the Sierra Nevada; in San Bernadino Mountains, the rate of tree growth has declined 75% c. Plants have increased susceptibility to disease and insect pests 3. Materials: damage to buildings, bridges, statues, books 4. Aesthetics : We don't like how it looks. We try to live in places without pollution, thus contributing to the problem by commuting II. Outdoor Air Pollutants A. Primary Pollutants: Sources B. Secondary Pollutants: Formation
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This is a simplified model of atmospheric cleansing by the hydroxyl radical. The first step is the photochemical destruction of ozone. The second step produces hydroxyl that reacts rapidly with many pollutants. Fig. 22.3 The threshold level for harmful effects diminishes with increasing exposure time. It differs for each pollutant. Fig. 22.4A
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CHAPTER 21 - CHAPTER 21 ATMOSPHERIC POLLUTION I. Air...

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