Basic Information

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The last 35 years have seen a growing commitment to clean air and a progression of science and technology that has informed decision-making. The Clean Air Rules of 2004 begin a new chapter in clean air history and encompass a strategy that will assure the years ahead are one of the most productive periods of air improvement in US history.

Implementation of the Clean Air Rules of 2004 will reduce air pollution and assure that well over half of the areas that currently have unhealthy air will meet the more protective, health-based ozone and fine particle standards by 2015. Their implementation will be achieved while protecting the nation's economic prosperity.

More Protective Standards

Clean Air Ozone Rules
The Clean Air Ozone Rules target ground level ozone, a significant health risk, especially for children with asthma. On April 15, 2004, EPA will fulfill its legal obligation under the Clean Air Act to issue final designations for all areas of the country stating that they either meet or do not meet the more protective 8-hour ozone standards. EPA will also issue a classification rule for nonattainment areas -- areas that do not meet the standards. The rule will classify the seriousness of the problem and will indicate the required actions that areas must take. States will develop implementation plans laying out what actions they will take to achieve cleaner air. As these plans are developed, EPA will work closely with state and local governments to improve their air quality rating and help nonattainment areas meet 8-hour standards. Because other coordinated actions address pollution that travels across state lines, many areas will be able to reach attainment without additional local actions.

Clean Air Fine Particles Rules
The Clean Air Fine Particles Rules target fine particles 2.5 microns or smaller in size. These fine particles are linked to significant health problems including increases in premature deaths and a range of serious respiratory and cardiovascular effects. States have already recommended which areas they believe do not meet the health-based fine particles standards (PM2.5). In July 2004, EPA will respond to those recommendations and in December, EPA will officially designate the areas that have been determined as either meeting or not meeting fine particle standards. EPA will also issue the implementation rule stating the required actions that areas must take. States will then develop implementation plans laying out the actions they will take to achieve clean air. The Clean Air Rules that address the interstate transport of these fine particles will bring the majority of these areas into attainment.

National Tools for Pollution that Crosses State Borders

Clean Air Interstate Rule
The proposed Clean Air Interstate Rule targets the sulfur dioxide (SO2) and nitrogen oxides (NOx) emissions from power plants that significantly contribute to pollution problems in other downwind states. These pollutants lead to the formation of fine particles and ground-level ozone that, together, are associated with thousands of premature deaths and illnesses each year. The Clean Air Interstate Rule proposed in December 2003 covers 29 states in the Eastern United States and the District of Columbia. The proposal offers options to use a mandatory cap and trade market incentives approach or a state-emissions budget approach that would allow states to choose other alternatives for achieving compliance. With full implementation of this proposal, SO2 and NOx emissions would be reduced by approximately 70 percent of pre-implementation levels. The Clean Air Interstate Rule addresses the largest source of transported emissions of NOx and SO2, coal-fired power plants. EPA plans to issue a final Clean Air Interstate Rule by December 2004.

Clean Air Mercury Rule
Under the Clean Air Mercury Rule proposed in December 2003, power plants will have to reduce their mercury emissions for the first time ever. Mercury in the air is transported across state and national boundaries. Once mercury falls to the earth's surface it is transformed to methylmercury, a persistent toxic pollutant and a serious public health issue. Methylmercury can accumulate in fish. Pregnant women who eat fish can pass on methylmercury to the developing fetus and, at high levels, this exposure may lead to negative developmental impacts. The Clean Air Mercury Rule proposal sets permanent mandatory emission-reduction caps for coal-fired power plants and uses a phased-in approach to provide industry flexibility in finding the best way to meet the reduction caps. Implementation of the proposed rule will reduce power plant emissions of mercury nationwide by 33 tons, nearly 70 percent at full implementation. EPA plans to issue a final Clean Air Mercury Rule by December 2004.

Clean Air Nonroad Diesel Rule
The proposed Clean Air Nonroad Diesel Rule reduces sulfur in fuels for diesel engines and sets tighter emission standards for diesel engines used in construction, agricultural, and industrial equipment. Diesel emissions are associated with serious health concerns including premature deaths and illnesses that result in loss of productivity from millions of lost workdays and thousands of lost school days. The proposal would reduce the allowable level of sulfur in diesel fuels by more than 99 percent. The proposed diesel standards will reduce emissions from Nonroad diesel engines by more than 90 percent. These requirements are similar to those for engines powering on-road trucks and buses. Nonroad diesel emissions currently account for about 44 percent of total diesel particulate matter and about 12 percent of total nitrogen oxides of the combined on-road and nonroad diesel emissions nationwide -- these percentages are even higher in some urban areas. EPA plans to issue a final Clean Air Nonroad Diesel Rule in Spring 2004.