Air Pollution Chapter 21. Atmosphere as a Resource

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1 Air Pollution Chapter 21 Atmosphere as a Resource Atmospheric Composition Nitrogen 78.08% Oxygen 20.95% Argon 0.93% Carbon dioxide 0.04% Ecosystem services Blocks UV radiation Moderates the climate Redistributes water in the hydrologic cycle Climate Processes and Air Pollution Air pollution is defined as any contaminant added to the air that is harmful to the health of living organisms. Due to the nature of air and wind, this pollution can be carried great distances. Industrial contaminants can be found in places that have virtually no population. Contaminants especially concentrate at the poles. Types of Air Pollution Two categories Primary Air Pollutant Harmful substance that is emitted directly into the atmosphere Secondary Air Pollutant Harmful substance formed in the atmosphere when a primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants Sources of Pollutants Stationary sources: are mainly power plants, factories Mobile sources: are mainly motor vehicles Affects mode of regulation as mobile sources more traditionally controlled at federal level Particulate Material Sulfur Oxides Carbon Oxides Hydrocarbons Major Classes of Air Pollutants

2 Particulate Material Thousands of different solid or liquid particles suspended in air Includes: soil particles, soot, lead, asbestos, sea salt, and sulfuric acid droplets Dangerous for 2 reasons May contain materials with toxic or carcinogenic effects Extremely small particles can become lodged in lungs Nitrogen and Sulfur Oxides Gases produced by the chemical interactions between atmospheric nitrogen and oxygen at high temperature Problems Greenhouse gases Cause difficulty breathing Sulfur Oxides Gases produced by the chemical interactions between sulfur and oxygen Causes acid precipitation Carbon Oxides and Hydrocarbons Carbon Oxides Gases carbon monoxide (CO) and carbon dioxide (CO 2 ) Greenhouse gases Hydrocarbons Diverse group of organic compounds that contain only hydrogen and carbon (ex: CH4- methane) Some are related to photochemical smog and greenhouse gases Ozone Tropospheric Ozone Man- made pollutant in the lower atmosphere Secondary air pollutant Component of photochemical smog Stratospheric Ozone Essential component that screens out UV radiation in the upper atmosphere Man- made pollutants (ex: CFCs) can destroy it Smog Formation Industrial smog Gray sooty smog Particulates and so2 Worse in winter Photochemical smog Mixture of pollutants form from VOC s, NOx, and sunlight main components are ozone, PAN s (peroxyacetyl nitrate)

3 Effects of Air Pollution Low level exposure Irritates eyes Causes inflammation of respiratory tract Can develop into chronic respiratory diseases Health Effects of Air Pollution Sulfur Dioxide and Particulate material Irritate respiratory tract and impair ability of lungs to exchange gases Nitrogen Dioxides Causes airway restriction Carbon monoxide Binds with iron in blood hemoglobin Causes headache, fatigue, drowsiness, death Causes burning eyes, coughing, and chest discomfort Children and Air Pollution Greater health threat to children than adults Air pollution can restrict lung development Children breath more often than adults Children who live in high ozone areas are more likely to develop asthma Indoor Air Pollution Indoor air pollution can have more significant effects on human health than outdoor pollution. People generally spend more time indoors. Cigarette smoke is the most common indoor air pollutant in the U.S. 430,000 die annually from a disease related to smoking. Less-developed countries also suffer from indoor air pollution. Organic fuels make up majority of household energy. These fuels are often burned in smoky, poorly ventilated heating and cooking fires. Economic Cost Smog Costs California $521 Million a Year; Kids, Asthmatics Hit Hardest Environmental Working Group (EWG), 2005 News: Los Angeles Smog Found Cause Of $1 Million in Crop Damage J. Agric. Food Chem., 1954 Effect of Climate

4 Warm cities have more solar input; can cause more photochemical smog Colder cities may have more added pollution in winter due to heating of buildings Thermal Inversions Normal air pattern is unstable Air should be warmer near earth; cooler as move up Inversion has cooler air below a cap of warmer air Cities more susceptible if in a valley and near a coast Cold air can subside down mountain and slip under warmer air Cities susceptible are: Los Angeles, Mexico City, Denver Air Quality Legislation 1963-first Air Quality Act 1970-first Clean Air Act Consolidated control under newly formed EPA Set NAAQS (ambient air quality standards) 1977-amendments 1990-major amendments to Clean Air Act new standards for ozone and particulates Clean Air Act The most significant parts of the U.S. Clean Air Act took effect in Initially, the law required the EPA to set and enforce limits for 6 different air pollutants. These are called criteria pollutants. Sulfur Dioxide Carbon Monoxide Particulates Lead Ozone Depletion in Stratosphere Protects earth from UV radiation Part of the electromagnetic spectrum with wavelengths just shorter than visible light thinning/hole First identified in 1985 over Antarctica Caused by human-produced bromine and chlorine containing chemicals Ex: CFCs Hole over Antarctica requires two conditions: Sunlight just returning to polar region

5 Circumpolar vortex- a mass of cold air that circulates around the southern polar region Isolates it from the warmer air in the rest of the planet Polar stratospheric clouds form Enables Cl and Br to destroy ozone Effects of Ozone Depletion Higher levels of UV-radiation hitting the earth Eye cataracts Skin cancer (right) Weakened immunity May disrupt ecosystems May damage crops and forests Recovery of Ozone Layer Montreal Protocol (1987) Reduction of CFCs Started using HCFCs (greenhouse gas) Phase out of all ozone destroying chemicals is underway globally Satellite pictures in 2000 indicated that ozone layer was recovering Full recovery will not occur until 2050 Air Pollution Control Most effective strategy for controlling pollution is to not produce it in the first place. Particulate Removal - Remove particles physically by trapping them in a porous mesh which allows air to pass through but holds back solids. Electrostatic Precipitators Pass air across electrically charged plates that attract the particles of pollution. Reducing Pollution Sulfur Dioxide Reduction Heating Fuel Switching Switch from soft coal with a high sulfur content (like was used in London in 1952) to low sulfur coal. Change to another fuel (natural gas). Limestone Injection Can reduce sulfur emissions by 90% by mixing crushed limestone with coal before it is fed into a boiler. International Efforts to Reduce Greenhouse Gas Emission Kyoto Protocol Legally binding Provides operational rules on reducing greenhouse gases US and Australia have not sign it- it will be difficult to implement without US backing