The Threat of Air Pollution

Transcription

1 Chapter 13: Air Pollution The Atmosphere: An Introduction to Meteorology, 12 th Lutgens Tarbuck Lectures by: Heather Gallacher, Cleveland State University The Threat of Air Pollution The Threat of Air Pollution Natural air pollution: Dust storms, ash from volcanoes, pollen and spores, and smoke from wildfires are all forms of natural air pollution. Human caused air pollution: Smoke, soot, and other gases from chimneys, smog, and carbon monoxide are among the human causes of air pollution. 1

2 Air pollutants are particles and gases in concentrations that endanger the health and wellbeing of organisms. Primary pollutants are emitted directly from identifiable sources. Secondary pollutants are produced via chemical reactions in the atmosphere with primary pollutants. Primary pollutants: These pollutants consist of particulate matter, which is a mixture of solid particles and liquid droplets found in the air. Fine particles are less than 2.5 micrometers in diameter These are from combustion, wood burning, and power generation. Coarse particles are less than 10 micrometers. These particles come from dirt roads and crushing and grinding operations. 2

3 Sulfur dioxide (SO 2 ) SO 2 is a colorless gas originating from the combustion of sulfur-containing fuel, such as coal and oil. Important sources are power plants, smelters, pulp and paper mills, and petroleum refineries. SO 2 is also a cause of acid rain. Nitrogen oxide (No x ) Nitrogen oxides are gases that form during the hightemperature combustion of fuel when nitrogen in the air or fuel reacts with oxygen. Motor vehicles and power plants are the primary sources. It is also a contributor to acid rain. Volatile organic compounds (VOCs): VOCs are also called hydrocarbons. They encompass a wide array of solids, liquids, and gases. Carbon monoxide (CO): CO is a colorless, odorless, and poisonous gas produced by the incomplete burning of coal, wood, and oil. More than three-quarters of U.S. emissions are from motor vehicles and nonroad equipment. Lead (Pb): Lead was formerly added to gasoline to prevent engine knock. Occasional violations still occur at lead smelters. 3

4 Secondary air pollution: Air pollution in urban and industrial areas is called smog, a combination of smoke and fog. Photochemical reactions are triggered by strong sunlight. Nitrogen oxides absorb sunlight in the presence of VOCs. It is a noxious mixture of gases and particulates. The major component is ozone. Volcanic smog (Vog): This occurs in active volcanoes. 4

5 Clean Air Act of 1970: It was responsible for the creation of the Environmental Protection Agency. This legislation set standards for the four primary pollutants as well as the secondary pollutant. Primary Particulates SO 2 NO x CO Secondary Ozone Short term: Acute effects refers to levels that might be life threatening within a period of hours or days. Long term: Chronic effects occur when levels cause gradual deterioration of fhysiological functions over a span of years. 5

6 Air Quality Index (AQI): The AQI is an indicator for reporting daily air quality to the general public. The EPA calculates the AQI for the five pollutants regulated by the Clean Air Act. The AQI scale runs from Less than 100 on the scale is good. Greater than 100 is considered unhealthy. 6

7 Meteorological Factors Affecting Air Pollution Wind as a factor Meteorological Factors Affecting Air Pollution The role of atmospheric stability: This determines how far the pollutants will move vertically. Mixing depth is the vertical distance between Earth s surface and the height of convectional movement. When air is stable, there is little convection and the mixing depths are small. When air is unstable air, there is greater convection and the mixing depths are large. Meteorological Factors Affecting Air Pollution Surface temp inversions 7

8 Meteorological Factors Affecting Air Pollution Inversions aloft Acid Precipitation Wet deposition: Through a series of chemical reactions, pollutants emitted from sources, such as power-generating plants, oresmelting, petroleum refining and motor vehicles of all kinds, are converted to acids then fall as rain or snow. Dry deposition Acid-producing chemicals may become incorporated into dust or smoke and then fall to the ground. Acid Precipitation Extent and potency of acid precipitation 8

9 Acid Precipitation Acid Precipitation Effects of acid precipitation It lowers the natural ph of lakes and rivers. It reduces agriculture yields. It corrodes metals and stone structures. End Of Chapter 13 9