| The Clean Air Act directs the Environmental Protection Agency (EPA) to set air quality standards for certain types of pollutants, referred to as "criteria pollutants," one of which is particulate matter. One of the criteria pollutants is particulate matter, which is made up of many different kinds of fine particles, including dust, dirt, soot, smoke, and liquid droplets that are suspended in the air. Particulate matter in the air creates a health risk particularly for children, the elderly, and people with respiratory problems. Particulate matter also causes chemical imbalances in soil and water and contributes to haze and reduced visibility. The EPA considers particulate matter pollution to be its most serious air quality problem. Originally, the EPA defined particulate pollution as that consisting of particles less than 10 microns in size. However, in the 1990's, it was determined that coarser particulates caused different health problems than did very fine particles, which could be more deeply inhaled into the lungs. Accordingly, as of 1997 the EPA regulates particulate matter pollution under two categories: coarse matter particulates (referred to as "PM10"), which are 2.5 to 10 microns in size, and fine matter particulates, which are less than 2.5 microns ("PM2.5").
In December 2004, the EPA issued its final report on particulate matter pollution, which was entitled The Particle Pollution Report: Current Understanding of Air Quality and Emissions through 2003. Among the major findings of the report was that both coarse and fine matter particulate levels have been improving. In 2003, fine matter particulates were at the lowest levels since monitoring was instituted in 1999; coarse matter particulates were at the second lowest levels. Fine matter has decreased 10 percent since 1999 and was 30 percent lower than the levels that were estimated to exist 25 years ago. Coarse matter particulates have decreased 7 percent since 1999 and have declined 31 percent from 1988, when monitoring of coarse matter particulates began.
Despite these successes, in 2003, 62 million Americans lived in 97 different counties that had particulate matter levels that exceeded the EPA's standards for either fine or coarse matter particulate levels, or both. On the other hand, the areas that had historically experienced the highest levels of particulate matters have showed the greatest improvements. For example, the northwest United States has experienced a 39 percent drop in coarse particulate matter from 1988 levels.
One of the biggest contributors to the improvements in particulate matter pollution has been the EPA's Acid Rain program, which has resulted in a 33 percent decrease in sulfur dioxide emissions from power plants. Reductions in vehicle emissions have also contributed to the improvements. Other programs instituted by the EPA or in the planning stages will provide continued decreases in particulate pollution, such as a new Nonroad Diesel Rule and the Clean Air Interstate Rule, which is addressed specifically at power plants in the eastern United States. The Best Available Retrofit Technology regulation will require older power plants to control particulate matter emissions by updating their existing pollution control equipment. Copyright 2010 LexisNexis, a division of Reed Elsevier Inc. |