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People residing in counties that fail to meet Primary National Ambient Air Quality Standards (NAAQS).
miles above the Earth's surface. For example, chlorine concentrations in the upper atmosphere resulting from the release of chlorofluorocarbons (CFCs) and certain other chemicals have increased to a level that damages the Earth's ozone layer, which shields the planet from harmful doses of solar radiation. Another concern is possible climate change due to the accumulation of greenhouse gases that trap heat in the atmosphere. Emissions of greenhouse gases are still growing, but the rate of increase has slowed over the last 20 years. With direct and indirect controls established on greenhouse gas emissions in the last four years, emissions are expected to rise by as little as 1-2 percent during the 1990s.
0 20 40 60 80 100
Millions of People Note: PM10 = particulate matter less than 10 micrometers in diameter (dust and soot). Numbers are for 1991 based on 1990 U.S. county population data. Sensitivity to air pollutants may vary from individual to individual.
Source: See Part II, Table 43. Ozone can cause respiratory problems in sensitive individuals exposed for extended periods and also can damage forests and crops.
Carbon monoxide and particulates also exceed federal limits in some areas. Moreover, relatively large annual releases of sulfur dioxide and nitrogen oxides contribute to acid rain, visibility degradation, and health risks for sensitive parts of the population. Toxic pollutants—those known or suspected to cause cancer or other serious health effects are released into the air in many areas. The latest EPA Toxics Release Inventory shows a total of 2.2 billion pounds of air toxics released nationwide in 1990.
Indoor Air Pollution
The population's general exposure to indoor air pollutants is increasing because of the following factors:
• Construction of more tightly sealed
Indoor air pollutants may include tobacco smoke, radon, volatile organic compounds, biological contaminants, combustion gases, respirable particulates, lead, formaldehyde, and asbestos. Scientific data is limited regarding exposures to and risks of indoor air pollution.
A focus of concern is radon, a naturally occurring gas that could be a leading cause of lung cancer in the United States. Although few homes have been tested (6 percent), federal and state
Global Atmospheric Pollution
All over the world, air pollutants cross international borders and rise
environmental agencies have detected elevated radon levels in some areas of every state.
Policies and Programs
Current U.S. policy on air quality is embodied in the Clean Air Act Amendments of 1990 (CAAA), which contain several innovative, market-based mechanisms to help reduce pollution. Major international initiatives include the U.N. Framework Convention on Climate Change, the Montreal Protocol on Substances that Deplete the Ozone Layer, and the U.S./Canada Bilateral Agreement on Air Quality.
amendments mandated significant air quality improvements:
• Attainment of air quality standards
Since passage of CAAA, EPA has proposed or finalized rules and guidance documents that together will accomplish more than three-quarters of the emission reductions called for under the act. In an effort to prevent the kind of hostile litigation that has delayed
Clean Air Act Amendments
When fully implemented, CAAA will reduce air pollutant emissions by 56 billion pounds annually. The
Leading powerplant emitters of sulfur dioxides.
Source: U.S. Environmental Protection Agency, National Air Quality Emissions and Trends Report, 1990, (Washington, DC: EPA, 1991).
environmental progress in the past, several rules were developed through regulatory negotiations and other forums in which industry, environmental groups, and state and local officials helped EPA develop regulatory proposals.
Market-Based Acid Rain Control
A prime example of the CAAA cost-effective, market-based methods is the acid rain control program, which employs an emission-allowance system to reduce annual nationwide sulfur dioxide emissions by up to 10 million tons per year, or roughly 50 percent below the 1980 level. Under this program, the federal government will allocate emission allowances to electric utilities whose powerplants emit sulfur dioxide. Nationwide emissions will be capped at the lower level and individual utilities must stay within their allowance limits. If, however, a utility can cut its emissions more than required, it can sell its extra allowances
to another utility, or bank them for future use. This creates an economic incentive to the utility to maximize its emissions reductions at the lowest possible cost.
Initially, concerns with the marketbased approach existed on two fronts. Some observers questioned whether a market actually would develop for the emission allowances, while others feared a lack of correspondence between the location of emission reductions and sensitive regions on the receiving end. Concerns over market development lessened substantially in 1992 when the Chicago Board of Trade established an allowance market; the first major transaction occurred in May 1992 when Wisconsin Power and Light sold 10,000 emission allowances to the Tennessee Valley Authority. Concerns over the distribution of pollution reductions have lessened because the cap on emissions will force all utilities to phase out older, dirtier equipment over time.
EPA has instituted a monitoring system to identify potential problem areas.
The following is a summary of other CAAA rules that EPA has proposed or finalized to date.
Cleaner Gasoline. National limits on gasoline’s volatility—its tendency to evaporate—already are reducing the release of hydrocarbons, which contribute to ozone smog. Starting in 1995 a new generation of cleaner, reformulated gasolines will reduce hydrocarbon and toxic emissions by at least 15 percent in the nine cities with the worst ozone pollution. A companion rule to increase the oxygen content of gasoline in 39 cities with carbon monoxide pollution will cut those emissions by an estimated 20 percent in 1993.
Cleaner Cars and Trucks. Tighter emissions limits for cars and light trucks will be phased in starting with 1994 models, cutting exhaust hydrocarbons by 30 percent and nitrogen oxides by 60 percent relative to current standards. A new cold-temperature standard is expected to reduce wintertime carbon monoxide emissions by 20 percent. Smoke from diesel trucks and buses will be cut by proposed particulate standards and by new limits on sulfur in diesel fuel.
Vehicle Inspection and Maintenance. High-tech vehicle inspection and proper maintenance could do more to improve urban air quality than any other single measure. Under a rule issued in 1992, EPA will require improved vehicle emissions inspection programs in cities having difficulty attaining federal standards for ambient levels of ozone and carbon monoxide. The rule also requires vehicle owners to tune-up or repair high-polluting vehicles.
Cash for Clunkers. An estimated 20 percent of all vehicles on the road
create more than 60 percent of autorelated air pollution. A proposed "cash for clunkers” program would allow states and industries to buy older, higher-polluting cars and trucks, retire them permanently, and use the resulting pollutant reductions to help satisfy federal clean air requirements. Several companies and organizations have conducted pilot tests of the program in conjunction with state and federal officials in California, Illinois, and Delaware.
Fleet Vehicles. Beginning in 1998 in 22 cities, EPA will require new fleet vehicles, such as taxis and delivery vans, to meet tailpipe standards more stringent than those required for conventional vehicles. EPA guidelines will provide incentives for fleet owners to purchase ultra-clean vehicles fueled with natural gas, propane, pure alcohol, or electricity.
Offshore Oil Facilities. Offshore oil and gas platforms within 25 miles of a state's seaward boundary will be subject to the same air pollution control requirements as onshore facilities.
Incinerators and Landfills. New standards for municipal waste incinerators will result in a 90-percent reduction in emissions of metals, organic chemicals, and acid gases. Proposed standards for large, solid waste landfills, as well as hazardous waste treatment and disposal facilities, would cut toxic and smog-forming emissions. The landfill standards also would cut releases of methane, a greenhouse gas.
Permits. To facilitate enforcement of the amendments, states will develop comprehensive permit programs for air pollution sources.
Hazardous Organics Rule. New standards cover emissions from such diverse sources as storage tanks, transfer operations, and wastewater treatment plants. As a result, toxic air