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Adapted from a document by the same name. US Environmental Protection Agency
Updated May 13, 2002

Plain English Guide To The Clean Air Act

Features of the 1990 Clean Air Act: The role of the federal government and the role of the states

Although the 1990 Clean Air Act is a federal law covering the entire country, the states do much of the work to carry out the Act. For example, a state air pollution agency holds a hearing on a permit application by a power or chemical plant or fines a company for violating air pollution limits.

Under this law, EPA sets limits on how much of a pollutant can be in the air anywhere in the United States. This ensures that all Americans have the same basic health and environmental protections. The law allows individual states to have stronger pollution controls, but states are not allowed to have weaker pollution controls than those set for the whole country.

The law recognizes that it makes sense for states to take the lead in carrying out the Clean Air Act, because pollution control problems often require special understanding of local industries, geography, housing patterns, etc.

States have to develop state implementation plans (SIPs) that explain how each state will do its job under the Clean Air Act. A state implementation plan is a collection of the regulations a state will use to clean up polluted areas. The states must involve the public, through hearings and opportunities to comment, in the development of each state implementation plan. EPA must approve each SIP, and if a SIP isn't acceptable, EPA can take over enforcing the Clean Air Act in that state. The United States government, through EPA, assists the states by providing scientific research, expert studies, engineering designs and money to support clean air programs.

Interstate air pollution

Air pollution often travels from its source in one state to another state. In many metropolitan areas, people live in one state and work or shop in an- other; air pollution from cars and trucks may spread throughout the interstate area. The 1990 Clean Air Act provides for interstate commissions on air pollution control, which are to develop regional strategies for cleaning up air pollution. The 1990 Clean Air Act includes other provisions to reduce interstate air pollution.

International air pollution

Air pollution moves across national borders. The 1990 law covers pollution that originates in Mexico and Canada and drifts into the United States and pollution from the United States that reaches Canada and Mexico.


One of the major breakthroughs in the 1990 Clean Air Act is a permit program for larger sources that release pollutants into the air. Requiring polluters to apply for a permit is not a new idea. Approximately 35 states have had state- wide permit programs for air pollution. The Clean Water Act requires permits to release pollutants into lakes, rivers or other waterways. Now air pollution is also going to be managed by a national permit system. Under the new program, permits are issued by states or, when a state fails to carry out the Clean Air Act satisfactorily, by EPA. The permit includes information on which pollutants are being released, how much may be released, and what kinds of steps the source's owner or operator is taking to reduce pollution, including plans to monitor (measure) the pollution. The permit system is especially useful for businesses covered by more than one part of the law, since information about all of a source's air pollution will now be in one place. The permit system simplifies and clarifies businesses' obligations for cleaning up air pollution and, over time, can reduce paperwork. For instance, an electric power plant may be covered by the acid rain, hazardous air pollutant and non-attainment (smog) parts of the Clean Air Act; the detailed information required by all these separate sections will be in one place--on the permit.

Permit applications and permits are available to the public; contact your state or regional air pollution control agency or EPA for information on access to these documents. Businesses seeking permits have to pay permit fees much like car owners paying for car registrations. The money from the fees will help pay for state air pollution control activities.


The 1990 Clean Air Act gives important new enforcement powers to EPA. It used to be very difficult for EPA to penalize a company for violating the Clean Air Act. EPA has to go to court for even minor violations. The 1990 law enables EPA to fine violators, much like a police officer giving traffic tickets. Other parts of the 1990 law increase penalties for violating the Act and bring the Clean Air Act's enforcement powers in line with other environmental laws.


The 1990 Clean Air Act sets deadlines for EPA, states, local governments and businesses to reduce air pollution. The deadlines in the 1990 Clean Air Act were designed to be more realistic than dead- lines in previous versions of the law, so it is more likely that these deadlines will be met.

Public participation

Public participation is a very important part of the 1990 Clean Air Act. Throughout the Act, the public is given opportunities to take part in deter- mining how the law will be carried out. For in- stance, you can take part in hearings on the state and local plans for cleaning up air pollution. You can sue the government or a source's owner or operator to get action when EPA or your state has not enforced the Act. You can request action by the state or EPA against violators.

The reports required by the Act are public documents. A great deal of information will be collected on just how much pollution is being released; these monitoring (measuring) data will be available to the public. The 1990 Clean Air Act ordered EPA to set up clearinghouses to collect and give out technical information. Typically, these clearinghouses will serve the public as well as state and other air pollution control agencies.

See the list at the end of this summary for organizations to contact for additional information about air pollution and the Clean Air Act.

Market approaches for reducing air pollution; economic incentives

The 1990 Clean Air Act has many features designed to clean up air pollution as efficiently and inexpensively as possible, letting businesses make choices on the best way to reach pollution cleanup goals. These new flexible programs are called market or market-based approaches. For instance, the acid rain clean-up program offers businesses choices as to how they reach their pollution reduction goals and includes pollution allowances that can be traded, bought and sold.

The 1990 Clean Air Act provides economic incentives for cleaning up pollution. For instance, gasoline refiners can get credits if they produce cleaner gasoline than required, and they can use those credits when their gasoline doesn't quite meet clean-up requirements.

Cleaning up air pollution: the programs in the 1990 Clean Air Act

Smog and other "criteria" air pollutants

A few common air pollutants are found all over the United States. These pollutants can injure health, harm the environment and cause property damage. EPA calls these pollutants criteria air pollutants because the agency has regulated them by first developing health-based criteria (science-based guidelines) as the basis for setting permissible levels. One set of limits (primary standard) protects health; another set of limits (secondary standard) is intended to prevent environmental and property damage. A geographic area that meets or does better than the primary standard is called an attainment area; areas that don't meet the primary standard are called nonattainment areas.

Although EPA has been regulating criteria air pollutants since the 1970 CAA was passed, many urban areas are classified as nonattainment for at least one criteria air pollutant. It has been estimated that about 90 million Americans live in nonattainment areas.


What we typically call smog is primarily made up of ground-level ozone. Ozone can be good or bad depending on where it is located. Ozone in the stratosphere high above the Earth protects human health and the environment, but ground-level ozone is the main harmful ingredient in smog.

Ground-level ozone is produced by the combination of pollutants from many sources, including smokestacks, cars, paints and solvents. When a car burns gasoline, releasing exhaust fumes, or a painter paints a house, smog-forming pollutants rise into the sky.

Often, wind blows smog-forming pollutants away from their sources. The smog-forming reactions take place while the pollutants are being blown through the air by the wind. This explains why smog is often more severe miles away from the source of smog-forming pollutants than it is at the source.

The smog-forming pollutants literally cook in the sky, and if it's hot and sunny, smog forms more easily. Just as it takes time to bake a cake, it takes time to cook up smog-several hours from the time pollutants get into the air until the smog gets really bad.

Weather and geography determine where smog goes and how bad it is. When temperature inversions occur (warm air stays near the ground instead of rising) and winds are calm, smog may stay in place for days at a time. As traffic and other sources add more pollutants to the air. the smog gets worse.

Since smog travels across county and state lines, when a metropolitan area covers more than one state (for instance, the New York metropolitan area includes parts of New Jersey and Connecticut), their governments and air pollution control agencies must cooperate to solve their problem. Governments on the East Coast from Maine to Washington, D.C., will have to work together in a multistate effort to reduce the area's smog problem.

Here's how the 1990 Clean Air Act reduces pollution from criteria air pollutants, including smog. First, EPA and state governors cooperated to identify nonattainment areas for each criteria air pollutant. Then, EPA classified the nonattainment areas according to how badly polluted the areas are. There are five classes of nonattainment areas for smog, ranging from marginal (relatively easy to clean up quickly) to extreme (will take a lot of work and a long time to clean up).

The 1990 Clean Air Act uses this new classification system to tailor clean-up requirements to the severity of the pollution and set realistic deadlines for reaching clean-up goals. If deadlines are missed, the law allows more time to clean up, but usually a nonattainment area that has missed a clean-up deadline will have to meet the stricter clean-up requirements set for more polluted areas.

Not only must nonattainment areas meet deadlines, states with nonattainment areas must show EPA that they are moving on clean-up before the deadline-making reasonable further progress. States will usually do most of the planning for cleaning up criteria air pollutants, using the permit system to make sure power plants, factories and other pollution sources meet their clean-up goals.

The comprehensive approach to reducing criteria air pollutants taken by the 1990 Act covers many different sources and a variety of clean-up methods. Many of the smog clean-up requirements involve motor vehicles (cars, trucks, buses). Also, as the pollution gets worse, pollution controls are required for smaller sources.

Other criteria pollutants: carbon monoxide and particulates

The carbon monoxide (CO) and particulate matter (PM-10) clean-up plans are set up like the plan for smog, but only two pollution classes are identified for each (instead of the five for ozone). Getting rid of particulates (soots, dusts, smoke) will require pollution controls on power plants and restrictions on smaller sources such as wood stoves, agricultural burning, and dust from fields and roads. Because so many homes have woodstoves and fireplaces, this summary of the Clean Air Act includes a section on Woodstoves and fireplaces, providing information on how the Clean Air Act will affect these home heating systems.

1997 Changes to the Clean Air Act

EPA recently reviewed the current air quality standards for ground-level ozone (commonly known as smog) and particulate matter (or PM). Based on new scientific evidence, revisions have been made to both standards. At the same time, EPA is developing a new program to control regional haze, which is largely caused by particulate matter.


What if a company wants to expand or change a production process or otherwise increase its output of a criteria air pollutant? If an owner or operator of a major source wants to release more of a criteria air pollutant, an offset (a reduction of the criteria air pollutant by an amount somewhat greater than the planned increase) must be obtained somewhere else, so that permit requirements are met and the nonattainment area keeps moving toward attainment. The company must also install tight pollution controls. An increase in a criteria air pollutant can be offset with a reduction of the pollutant from some other stack at the same plant or at another plant owned by the same or some other company in the nonattainment area. Since total pollution will continue to go down, trading offsets among companies is allowed. This is one of the market approaches to cleaning up air pollution in the Clean Air Act.

Criteria air pollutants in gasoline and consumer products

Volatile organic compounds (VOCs), important smog-forming chemicals, are found in gasoline and many consumer products, from hair spray to charcoal starter fluid to plastic popcorn packaging. This summary includes a section on Consumer Products; see that section for information on how the Clean Air Act will affect products you use every day. Information on changes in gasoline will be found in the section on Mobile Sources.

Hazardous air pollutants

Some air pollutants can cause cancer, problems with having children and other very serious illnesses as well as environmental damage. Air pollutants have killed people swiftly when large quantities were released; the 1984 release of methyl isocyanate at a pesticide-manufacturing plant in Bhopal, India, killed approximately 4,000 people and injured more than 200,000.

EPA refers to chemicals that cause serious health and environmental hazards as hazardous air pollutants (HAPs) or air toxics. Air toxics are released from sources throughout the country and from motor vehicles. For example, gasoline contains toxic chemicals. Gases escape from liquid gasoline and form a vapor in a process called vaporization or evaporation. When you put gas in your car, you can often see wavy lines in the air at the pump nozzle and you can smell gasoline; that tells you gasoline vapors are in the air. When cars and trucks burn gasoline, air toxics come out of the tailpipes. (These air toxics are combustion products--chemicals that are produced when a substance is burned.)

Air toxics are released from small stationary sources, such as dry cleaners and auto paint shops Large stationary sources, such as chemical factories and incinerators, also release hazardous air pollutants. The 1990 Clean Air Act deals more strictly with large sources than small ones, but EPA must regulate small sources of hazardous air pollutants as well.

To reduce air toxics pollution, EPA must first identify the toxic pollutants whose release should be reduced. The 1970 Clean Air Act gave EPA authority to list air toxics for regulation and then to regulate the chemicals. The agency listed and regulated seven chemicals through 1990. The 1990 Act includes a list of 189 hazardous air pollutants selected by Congress on the basis of potential health and/or environmental hazard; EPA must regulate these listed air toxics. The 1990 Act allows EPA to add new chemicals to the list as necessary.

To regulate hazardous air pollutants, EPA must identify categories of sources that release the 189 chemicals listed by Congress in the 1990 Clean Air Act. Categories could be gasoline service stations, electrical repair shops, coal-burning power plants, chemical plants, etc. The air toxics producers are to be identified as major (large) or area (small) sources.

Once the categories of sources are listed, EPA will issue regulations. In some cases, EPA may have to specify exactly how to reduce pollutant releases, but wherever possible companies will have flexibility to choose how they meet requirements. Sources are to use Maximum Available Control Technology (MACT) to reduce pollutant releases; this is a very high level of pollution control.

EPA must issue regulations for major sources first, and must then issue regulations to reduce pollution from small sources, setting priorities for which small sources to tackle first, based on health and environmental hazards, production volume, etc.

If a company wishes to increase the amount of air toxics coming out of an operating plant, the company may choose to offset the increases so that total hazardous air pollutant releases from the plant do not go up. Otherwise, they may choose to install pollution controls to keep pollutants at the required level.

If a company reduces its releases of a hazardous air pollutant by about 90 percent before EPA regulates the chemical, the company will get extra time to finish cleaning up the remaining 10 percent. This early reduction program is expected to result in a speedy reduction of the levels of several important hazardous air pollutants.

Under the 1990 Clean Air Act, EPA is required to study whether and how to reduce hazardous air pollutants from small neighborhood polluters such as auto paint shops, print shops, etc. The agency will also have to look at air toxics pollution after the first round of regulations to see whether the remaining health hazards require further regulatory action.

Cars, trucks, buses and other mobile sources release large amounts of hazardous air pollutants like formaldehyde and benzene. Cleaner fuels and engines and making sure that pollution control devices work should reduce hazardous air pollutants from mobile sources.

The Bhopal tragedy inspired the 1990 Clean Air Act requirement that factories and other businesses develop plans to prevent accidental releases of highly toxic chemicals. The Act establishes the Chemical Safety Board to investigate and report on accidental releases of hazardous air pollutants from industrial plants. The Chemical Safety Board will operate like the National Transportation Safety Board (NTSB), which investigates plane and train crashes.

Mobile sources (cars, trucks, buses, off-road vehicles, planes, etc.)

Each of today's cars produces 60 to 80 percent less pollution than cars in the 1960s. More people are using mass transit. Leaded gas is being phased out, resulting in dramatic declines in air levels of lead, a very toxic chemical. Despite this progress, most types of air pollution from mobile sources have not improved significantly.

At present the United States:

  • Motor vehicles are responsible for up to half of the smog-forming VOCs and nitrogen oxides (NOx).
  • Motor vehicles release more than 50 percent of the hazardous air pollutants.
  • Motor vehicles release up to 90 percent of the carbon monoxide found in urban air.
What went wrong?
  • More people are driving more cars more miles on more trips. In 1970, Americans traveled 1 trillion miles in motor vehicles, and we are expected to drive 4 trillion miles each year by 2000.
  • Many people live far from where they work; in many areas, buses, subways, and commuter trains are not available. Also, most people still drive to work alone, even when van pools, HOV (high-occupancy vehicle) lanes and other alternatives to one-person-per-car commuting are available.
  • Buses and trucks, which produce a lot of pollution, haven't had to clean up their engines and exhaust systems as much as cars.
  • Auto fuel has become more polluting. As lead was being phased out, gasoline refiners changed gasoline formulas to make up for octane loss, and the changes made gasoline more likely to release smog-forming VOC vapors into the air.

Although cars have had pollution control devices since the 1970s, the devices only had to work for 50,000 miles, while a car in the United States is usually driven for 100,000 miles.

The 1990 Clean Air Act takes a comprehensive approach to reducing pollution from motor vehicles. The Act provides for cleaning up fuels, cars, trucks, buses and other motor vehicles. Auto inspection provisions were included in the law to make sure cars are well maintained. The 1990 law also includes transportation policy changes that can help reduce air pollution.

Cleaner fuels

It will be very difficult to obtain a significant reduction in pollution from motor vehicles unless fuels are cleaned up. The 1990 Clean Air Act will clean up fuels. The phaseout of lead from gasoline will be completed by January 1, 1996. Diesel fuel refining must be changed so that the fuels contain less sulfur, which contributes to acid rain and smog.

Gasoline refiners will have to reformulate gasoline sold in the smoggiest areas; this gasoline will contain less volatile organic compounds (VOCs) such as benzene (which is also a hazardous air pollutant that causes cancer and aplastic anemia, a potentially fatal blood disease). Other polluted areas can ask EPA to include them in the reformulated gasoline marketing program. In some areas, wintertime carbon monoxide (CO) pollution is caused by people starting their cars. In these areas, refiners will have to sell oxyfuel, gasoline with oxygen added to make the fuel burn more efficiently, thereby reducing carbon monoxide release.

All gasolines will have to contain detergents, which, by preventing build-up of engine deposits, keep engines working smoothly and burning fuel cleanly. Low VOC, oxyfuel and detergent gasolines are already sold in several parts of the country.

The 1990 Clean Air Act encourages development and sale of alternative fuels such as alcohols, liquefied petroleum gas (LPG) and natural gas. Gas stations in smoggy areas will install vapor recovery nozzles on gas pumps. These nozzles cut down on vapor release when you put gas in your car.

Cleaner cars

The 1990 Clean Air Act requires cars to have under-the-hood systems and dashboard warning lights that check whether pollution control devices are working properly. Pollution control devices must work for 100,000 miles, rather than the current 50,000 miles. Auto makers must build some cars that use clean fuels, including alcohol, and that release less pollution from the tailpipe through advanced engine design. Electric cars, which are low-pollution vehicles, will also be built. Since California, especially southern California, has the worst smog problems, manufacturers will first sell clean fuel cars in a pilot project in California. By 1999, at least 500,000 of these clean fuel cars are to be manufactured for sale in California each year. Other states can require that cars meeting the California standards be sold in their states.

Many companies and government agencies have fleets of cars. Fleet-owners in very smoggy areas must buy the new cleaner cars starting in the late 1990s.

Inspection and maintenance (I/M) programs

Under the 1990 Clean Air Act, auto manufacturers will build cleaner cars, and cars will use cleaner fuels. However, to get air pollution down and keep it down, a third program is needed; vehicle inspection and maintenance (I/M), which makes sure cars are being maintained adequately to keep pollution emissions (releases) low. The 1990 Clean Air Act includes very specific requirements for inspection and maintenance programs.

Before the 1990 Clean Air Act went into effect, seventy United States cities and several states already had auto emission inspection programs. The 1990 law requires inspection and maintenance programs in more areas: forty metropolitan areas, including many in the northeastern United States, are required to start emission inspection and maintenance programs.

Some areas that already have inspection and maintenance programs are required to enhance (improve) their emission inspection machines and procedures. Enhanced inspection and maintenance machines and procedures will give a better measurement of the pollution a car releases when it is actually being driven, rather than just sitting parked at the inspection station. Enhanced inspection and maintenance programs may result in changes in where cars are inspected in your local area. Since the enhanced emission inspection and maintenance machines are expensive, some of the private stations now conducting inspection and maintenance programs may not want to buy the enhanced machinery. But the added expense for the new machinery will be more than made up for by air pollution reductions: emission inspection and maintenance programs are expected to have a big payoff in reducing air pollution from cars.

Cleaner trucks and buses

Starting with model year 1994, engines for new big diesel trucks will have to be built to reduce particulate (dust, soot) releases by 90 percent. Buses will have to reduce particulate releases even more than trucks. To reduce pollution, companies and governments that own buses or trucks will need to buy new clean models. Small trucks will be cleaned up by requirements similar to those for cars.

Non-road vehicles

Locomotives, construction equipment and even riding mowers may be regulated under the 1990 Clean Air Act. Air pollution from locomotives must be reduced. For the other non-road vehicles, EPA must issue regulations if a study shows that controls would help cut pollution.

Transportation policies

The smoggiest metropolitan areas will have to change their transportation policies to discourage unnecessary auto use, and to encourage efficient commuting (van pools, HOV [high-occupancy vehicle] lanes, etc.). States carrying out the 1990 Clean Air Act may add surcharges to parking fees.

Acid rain

You've probably heard of "acid rain". But you may not have heard of acid snow, acid fog or mist, acid gas and acid dust. All of these "acids" are related air pollutants, and can harm your health, cause hazy skies and damage the environment and your property. The 1990 Clean Air Act includes an innovative program to reduce acid air pollutants (all referred to here as "acid rain").

The acid rain that has received the most attention is caused mainly by pollutants from big coalburning power plants in the Midwest. These plants burn Midwestern and Appalachian coal, some of which contains a lot of sulfur compared to Western coal. Sulfur in coal becomes sulfur dioxide (S02) when coal is burned. Big power plants burn large quantities of coal, so they release large amounts of sulfur dioxide, as well as NOx (nitrogen oxides). These are acid chemicals, related to two strong acids: sulfuric acid and nitric acid.

The sulfur dioxide and nitrogen oxides released from the Midwestern power plants rise high into the air and are carried by winds toward the East Coast of the U.S. and Canada. When winds blow the acid chemicals into areas where there is wet weather, the acids become part of the rain, snow or fog. In areas where the weather is dry, the acid chemicals may fall to Earth in gases or dusts. Lakes and streams are normally slightly acid, but acid rain can make them very acid. Very acid conditions can damage plant and animal life.

Acid lakes and streams have been found all over the country. For instance, lakes in Acadia National Park on Maine's Mt. Desert Island have been very acidic, due to pollution from the Midwest and the East Coast. Streams in Maryland and West Virginia, lakes in the Upper Peninsula of Michigan, and lakes and streams in Florida have also been affected by acid rain. Heavy rainstorms and melting snow can cause temporary increases in acidity in lakes and streams in the eastern and western United States. These temporary increases may last for days or even weeks.

Acid rain has damaged trees in the mountains of Vermont and other states. Red spruce trees at high altitudes appear to be especially sensitive to acid rain. The pollutants that cause acid rain can make the air hazy or foggy; this has occurred in the eastern United States, including some mountain areas popular with vacationers, such as the Great Smokies.

Acid rain does more than environmental damage; it can damage health and property as well. Acid air pollution has been linked to breathing and lung problems in children and in people who have asthma. Even healthy people can have their lungs damaged by acid air pollutants. Acid air pollution can eat away stone buildings and statues.

Health, environmental and property damage can also occur when sulfur dioxide pollutes areas close to its source. Sulfur dioxide pollution has been found in towns where paper and wood pulp are processed and in areas close to some power plants. The 1990 Clean Air Act's sulfur dioxide reduction program will complement health-based sulfur dioxide pollution limits already in place to protect the public and the environment from both nearby and distant sources of sulfur dioxide.

The Act takes a new nationwide approach to the acid rain problem. The law sets up a marketbased system designed to lower sulfur dioxide pollution levels. Beginning in the year 2000, annual releases of sulfur dioxide will be about 40 percent lower than the 1980 levels. Reducing sulfur dioxide releases should cause a major reduction in acid rain.

Phase I of the acid rain reduction program goes 4 into effect in 1995. Big coal-burning boilers in 110 power plants in 21 Midwest, Appalachian, Southeastern and Northeastern states will have to reduce releases of sulfur dioxide. In 2000, Phase II of the acid rain program goes into effect, further reducing the sulfur dioxide releases from the big coal-burning power plants and covering other smaller polluters. Total sulfur dioxide releases for the country's power plants will be permanently limited to the level set by the Clean Air Act for the year 2000.

Reductions in sulfur dioxide releases will be obtained through a program of emission (release) allowances. EPA will issue allowances to power plants covered by the acid rain program; each allowance is worth one ton of sulfur dioxide released from the smokestack. To obtain reductions in sulfur dioxide pollution, allowances are set below the current level of sulfur dioxide releases. Plants may only release as much sulfur dioxide as they have allowances. If a plant expects to release more sulfur dioxide than it has allowances, it has to get more allowances, perhaps by buying them from another power plant that has reduced its sulfur dioxide releases below its number of allowances and therefore has allowances to sell or trade. Allowances can also be bought and sold by "middlemen", such as brokers, or by anyone who wants to take part in the allowances market. Allowances can be traded and sold nationwide. There are stiff penalties for plants which release more pollutants than their allowances cover.

The acid rain program provides bonus allowances to power plants for (among other things) installing clean coal technology that reduces sulfur dioxide releases, using renewable energy sources (solar, wind etc.) or encouraging energy conservation by customers so that less power needs to be produced.

All power plants under the acid rain program will have to install continuous emission monitoring systems (CEMS), machines that keep track of how much sulfur dioxide and nitrogen oxides the plant is releasing. A power plant's program for meeting its sulfur dioxide and nitrogen oxide limit will appear on the plant's permit, which will be filed with the state and EPA.

To cut down on nitrogen oxide pollution, EPA will require power plants to reduce their nitrogen oxide releases, and will require reductions in nitrogen oxide releases from new cars. Reducing nitrogen oxide releases will reduce both acid rain and smog formation.

The flexible market-based acid rain reduction program is expected to be a model for pollution control efforts in the United States and other countries.

Repairing the ozone layer

Scientists have found "holes"[3] in the ozone layer high above the Earth. The 1990 Clean Air Act has provisions for fixing the holes, but repairs will take a long time. Ozone in the stratosphere, a layer of the atmosphere nine to 31 miles above the Earth, serves as a protective shield, filtering out harmful sun rays, including a type of sunlight called ultraviolet B. Exposure to ultraviolet B has been linked to development of cataracts (eye damage) and skin cancer.

In the mid 1970s, scientists suggested that chlorofluorocarbons (CFCs) could destroy stratospheric ozone. CFCs were widely used then as aerosol propellants in consumer products such as hairsprays and deodorants, and for many uses in industry. Because of concern about the possible effects of CFCs on the ozone layer, in 1978 the U.S. government banned CFCs as propellants in aerosol cans.

Since the aerosol ban, scientists have been measuring the ozone layer. A few years ago, an ozone hole was found above Antarctica, including the area of the South Pole. This hole, which has been appearing each year during the Antarctic winter (our summer), is bigger than the continental United States. More recently, ozone thinning has been found in the stratosphere above the northern half of the United States; the hole extends over Canada and up into the Arctic regions (the area of the North Pole). The hole was first found only in winter and spring, but more recently has continued into summer. Between 1978 and 1991, there was a 4-5 percent loss of ozone in the stratosphere over the United States; this is a significant loss of ozone. Ozone holes have also been found over northern Europe.

What could a thinned-out ozone layer do to people's lives? There could be more skin cancers and cataracts. Scientists are looking into possible harm to agriculture, and there is already some evidence of damage to plant life in Antarctic seas.

Evidence that the ozone layer is dwindling led 93 nations, including the major industrialized nations, to agree to cooperate in reducing production and use of chemicals that destroy the ozone layer. As it became clear that the ozone layer was thinning even more quickly than first thought, the agreement was revised to speed up the phase-out of ozone-destroying chemicals.

Unfortunately, it will be a long time before we see the ozone layer repaired. Because of the ozone-destroying chemicals already in the stratosphere and those that will arrive within the next few years, ozone destruction will likely continue for another twenty years.

The 1990 Clean Air Act sets a schedule for ending production of chemicals that destroy stratospheric ozone. Chemicals that cause the most damage will be phased out first. The phase-out schedule can be speeded up if an earlier end to production of ozone-destroying substances is needed to protect the ozone layer. The table on this page on Ozone-destroying chemicals includes "speeded-up" phase-out dates which were proposed by EPA in early 1993.

Ozone-destroying chemicals
Name Use When U. S. production ends*
solvents, aerosol sprays (most spray can uses banned in 1970s) foaming agents in plastic manufacture January 1, 1996
Halons fire extinguishers January 1, 1994
solvents, chemical manufacture; carbon tetrachloride causes cancer in animals January 1, 1996
Methyl chloroform
very widely-used solvent; in many workplace and consumer solvents, including auto repair and maintenance products January 1, 1996
(hydro CFCs)
CFC substitutes, chemicals slightly different from CFCs January 1, 2003**

*The 1990 Clean Air Act includes a schedule for ending United States production of ozone-destroying chemicals and provisions for speeding up the phase out schedule if that is necessary. The dates in this table are "speeded-up" dates, proposed by EPA in early 1993.

**Production of the HCFC with the most severe ozone destroying effects will end by January 1, 2003. Production of the rest of the HCFCs will end by January 1, 2030.

CFCs, Halons, HCFCs (hydrochlorofluorocarbons)[4] and other ozone-destroying chemicals were listed by Congress in the 1990 Clean Air Act and must be phased out. The Act also lets EPA list other chemicals that destroy ozone.

EPA issues allowances to control manufacture of chemicals being phased out. Companies can also sell unused allowances to companies still making the chemicals or can use the allowances, within certain limits, to make a different, less ozone-destroying chemical on the phase-out list.

In addition to requiring the phasing out of production of ozone-destroying chemicals, the Clean Air Act takes other steps to protect the ozone layer. The law requires recycling of CFCs and labeling of products containing ozone-destroying chemicals. The 1990 Clean Air Act also encourages the development of "ozone-friendly" substitutes for ozone-destroying chemicals.

CFCs from car air conditioners are the biggest single source of ozone-destroying chemicals. By the end of 1993, all car air conditioner systems must be serviced using equipment that recycles CFCs and prevents their release into the air. Larger auto service shops were required to start using this special equipment in January 1992. Only specially-trained and certified repair persons will be allowed to buy the small cans of CFCs used in servicing auto air conditioners.

As CFCs and related chemicals are phased out, appliances and industrial processes that now use the chemicals will change. For example, industrial and home refrigerators will be changed to use refrigerants that don't destroy ozone. In the meantime, refrigerator servicing and disposal will have to be done in ways that don't release CFCs. Methyl chloroform, also called l,l,l-trichloroethane, which will be phased out by 1996, is a very widely-used solvent found in products such as automobile brake cleaners (often sold as aerosol sprays) and spot removers used to take greasy stains off fabrics. Replacing methyl chloroform in workplace and consumer products will lead to changes in many products and processes.

As substitutes are developed for ozone-destroying substances, before the chemicals can be produced and sold, EPA must determine that the replacements will be safe for health and the environment.

Consumer products containing CFCs and other ozone-destroying chemicals will have to be reformulated; these are discussed in the following section on Consumer products.

Consumer products

Hair sprays, paints, foam plastic products (such as disposable styrofoam coffee cups), carburetor and choke sprays-all are consumer products that may be regulated under the 1990 Clean Air Act. These products will be regulated to reduce releases of smog-forming VOCs and ozone-destroying chemicals (CFCs and related chemicals).

By May 1993, consumer products containing CFCs and related chemicals identified in the 1990 Clean Air Act as most damaging to the ozone layer have this label:

WARNING: contains or manufactured with (name of chemical), a substance which harms public health and the environment by destroying ozone in the upper atmosphere.

All products containing less destructive ozone destroying chemicals identified in the 1990 Act must be labeled by 2015. Consumers should be aware of product changes and any safety or health problems that may be caused by the new ozone-safe formulations. Material safety data sheets for the products should be read for health and safety information and information on how to use and dispose of the product.

Home woodstoves

Woodstoves and fireplace inserts have become very popular in the past twenty years. Although these woodburning heat suppliers are relatively cheap to operate, they have some disadvantages, including polluting the air. In some areas of the country, wintertime air pollution from wood smoke has become so bad that governments have had to curtail the use of woodstoves and fireplaces under certain weather and pollution conditions.

Wood smoke often contains a lot of particulates (dust, soot) and much higher levels of hazardous air pollutants, including some cancer-causing chemicals, than smoke from oil- or gas-fired furnaces. Steps to clean up wood smoke pollution have included redesigning the burning system in woodstoves; newer woodstoves put out much less pollution than older models.

Under the 1990 Act, EPA has issued guidelines for reducing pollution from home wood-burning. These guidelines, which are not requirements, include design information for less-polluting stoves and fireplaces.

How do you know the Clean Air Act is working?

Everyone in the United States has a role to play to make the Clean Air Act a success. One of the most important things Americans can do is to keep track of how the law is working.

There are several ways you'll be able to tell how well the Clean Air Act is working. EPA, state, regional and local air pollution control agencies have to issue regulations (rules), give out permits, enforce the Act against violators and do other things described in the Clean Air Act.

Many groups with an interest in how the Clean Air Act works are watching EPA and the other air pollution control agencies. These groups include local and national business and trade organizations (from state associations of dry cleaners to the United States Chamber of Commerce), local community organizations (such as neighborhood associations), and local and national environmental and public health organizations (such as the Clean Air Network of the Natural Resources Defense Council and the American Lung Association). If you belong to one or more of these groups, their bulletins or newsletters will keep you informed.

Newspapers, radio and television will report on how the Act is being carried out, both nationally and in your local area. You can also contact EPA and your state, regional or local air pollution control agencies to receive information directly on Clean Air Act activities.

The United States Congress monitors how federal agencies are carrying out the laws. Contact your Congressional representative or your Senator to get more information on Congressional hearings and reports on how EPA is carrying out the Clean Air Act. You can also request reports from the United States General Accounting Office (GAO), the Congressional investigative agency which reviews how EPA carries out the Clean Air Act. State legislatures review how state agencies carry out air pollution control laws. Ask your state representative for more information.

Over time, the Clean Air Act will reduce air pollution. How will you know this is happening? Sometimes reduced pollution causes changes so great you can literally see the difference: the air is much cleaner and clearer than it was! But you can only be sure there has been a permanent change for the better if the good air continues for a long time weeks, months or years, during different weather conditions.

Monitoring air quality is the best way to know if the air is getting cleaner, because monitoring produces numbers that tell how much of a pollutant is in the air. You can request EPA, state or local monitoring reports that show changes over time. For example, sulfur dioxide levels will drop as power plants and other sources are cleaned up. This clean-up will happen in stages through the year 2000, so monitoring reports will tell you how the cleanup is going. Your eyes, nose and throat may also detect the change as smoggy areas clean up, but monitoring data remain the best way to check on overall improvement in air quality over time.

Monitoring will be carried out by EPA, state and regional air pollution control agencies, and by the owners of individual sources. Air pollution monitoring stations are set up all over the country, collecting information on various pollutants. Contact EPA, your state, regional or local air pollution control agency, for information on monitoring programs and monitoring reports.

How will you know the Clean Air Act is improving the environment? Some environmental improvements will be relatively easy to detect. People who live in the eastern United States should see much less summertime haze. Also, we'll know the ozone level is increasing in the stratosphere because scientists measure ozone content. What about lakes and streams harmed by acid rain and acid aerosols? We should see improvement as sulfur dioxide and nitrogen oxide levels decline, resulting in decreased acid rain and acid aerosols, but we don't know exactly how long it will take to restore lakes and streams and we don't know exactly what the lakes and streams and their inhabitants, including fish, will be like when air pollution is reduced.

What will be the benefits for human health of reductions in air pollution? People who now live in smoggy areas will have less eye, nose and throat irritation as smog levels are reduced. Reductions in air pollution will also lead to declines in cancer and other serious health problems.

Keep an eye on the Clean Air Act; it could change your life!

This document is not necessarily endorsed by the Almanac of Policy Issues. It is being preserved  in the Policy Archive for historic reasons.

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