Air Environment Chapter 7 PDF

AIR ENVIRONMENT CHAPTER 7 ENVIRONMENTAL SCIENCE CHAPTER 7 AIR ENVIRONMENT  What Is the Nature of the Atmosphere? The two innermost layers of the atmosphere are the troposphere, which supports life, and the stratosphere, which contains the protectiv...

AIR ENVIRONMENT CHAPTER 7 ENVIRONMENTAL SCIENCE CHAPTER 7 AIR ENVIRONMENT  What Is the Nature of the Atmosphere? The two innermost layers of the atmosphere are the troposphere, which supports life, and the stratosphere, which contains the protective ozone layer.  The Atmosphere Consists of Several Layers ATMOSPHERE - We live at the bottom of a thin envelope of gases surrounding the Earth, called atmosphere. - It is divided into several spherical layers. Density varies Decreases with altitude Atmospheric pressure Decreases with altitude  What is Air Pollution? Air pollution Is the presence of chemicals in the atmosphere in concentrations high enough to harm organisms, ecosystem, or human made materials, or to alter climate. Natural sources Dust blown by wind Pollutants from wildfires and volcanoes Volatile organics released by plants  Air Pollution Comes from Natural and Human Sources Stationary sources: power plants and industrial facilities Mobile sources: motor vehicles Natural sources: volcanoes, wildfires  Some Pollutants in the Atmosphere Combine to Form Other Pollutants Primary pollutants Are harmful chemicals emitted directly into the air from natural processes and human activities. Secondary pollutants While in the atmosphere, some primary pollutants reacts with one another and with one another and with other normal components of air to form new Indoor Air Pollution in Bangladesh harmful chemicals.  Human Impact on Atmosphere Burning Fossil Fuels  Adds CO2 and O3 to troposphere  Global Warming  Altering Climates  Produces Acid Rain Using Nitrogen  Releases NO, NO2, N2O, and NH3 fertilizers into troposphere  Produces acid rain Refining petroleum and  Releases SO2 into troposphere burning fossil fuels  Releases toxic heavy metals (Pb, Manufacturing Cd, and As) into troposphere  Criteria Air Pollutants EPA uses six "criteria pollutants" as indicators of air quality 1. Nitrogen Dioxide: NO2 2. Ozone: ground level O3 3. Carbon monoxide: CO 4. Lead: Pb 5. Particulate Matter: PM10 (PM 2.5) 6. Sulfur Dioxide: SO2 Volatile Organic Compounds: (VOCs) EPA established for each concentrations above which adverse effects on health may occur Carbon Monoxide (CO) Properties: colorless, odorless, heavier than air, 0.0036% of atmosphere Effects: binding to hemoglobin, dizziness, shortness of breath, fatigue, nausea, brain damage, death Sources: incomplete combustion of fossil fuels; 60 - 95% from auto exhaust Class: carbon oxides (CO2, CO) EPA Standard: 9 ppm 5.5 billion tons enter atmosphere/year  Nitrogen Dioxide (NO2) Properties: reddish brown gas, formed as fuel burnt in car, strong oxidizing agent, forms Nitric acid in air Effects: acid rain, lung and heart problems, decreased visibility (yellow haze), suppresses plant growth Sources: fossil fuels combustion at higher temperatures, power plants, forest fires, volcanoes, bacteria in soil Class: Nitrogen oxides (NOx) EPA Standard: 0.053 ppm  Sulfur Dioxide (SO2) Properties: colorless gas with irritating odor Effects: produces acid rain (H2SO4), breathing difficulties, eutrophication due to sulfate formation, lichen and moss are indicators Sources: burning high sulfur coal or oil, smelting or metals, paper manufacture Class: sulfur oxides EPA Standard: 0.3 ppm (annual mean)  Suspended Particulate Matter (PM10) Properties: particles suspended in air (