National Assessment of Toxic Air Pollutants

AEN News

Washington - Recent news reports of an analysis of EPA data have generated significant interest in toxic air pollution. EPA has not issued a new report; the data has been available on EPA's Web site since Feb. 22.

The data in the second National-Scale Air Toxics Assessment (NATA) is not a method for comparing one area of the country to another. Rather it is an important tool to guide further local, state and federal steps to cut toxic air pollution and build upon the significant emissions reductions achieved since 1990. It is a state-of-the-science screening tool that estimates cancer and other health risks from exposure to air toxics.

The United States has made significant progress in reducing air toxics from industry, fuels and vehicles, and indoor sources. Since the Clean Air Act was amended in 1990, the EPA has issued 96 standards for 174 different types of industrial sources of air toxics, including chemical plants, oil refineries, aerospace manufacturers and steel mills.

The agency also has issued regulations for 15 categories of smaller sources, such as dry cleaners, commercial sterilizers, secondary lead smelters and chromium electroplating facilities. Together, these standards are projected to reduce annual emissions of air toxics by about 1.7 million tons from 1990 levels when fully implemented. It is important to note that the NATA information was based on 1999 data. Thus it does not represent seven years of progress in air quality.

By 2030 EPA's proposed Mobile Source Air Toxic (MSAT) regulations and fuel and vehicle standards already in place will reduce toxic emissions from passenger vehicles to 80 percent below 1999 emissions.

The MSAT proposal would set new benzene standards for gasoline, hydrocarbon emissions standards for passenger vehicles at cold temperatures and evaporative standards for fuel containers. Once the new standards are fully implemented in 2030, they are expected to reduce emissions of mobile source air toxics annually by 350,000 tons, including 65,000 tons of benzene.

NATA is not designed to be used as the sole basis for regulatory action. The results of the assessment, however, will help EPA and state and local air quality regulators identify pollutants and sources of greatest concern and set priorities for addressing that pollution. NATA also will help identify areas where EPA needs to collect additional information to improve the understanding of risks from air toxics exposure.

NATA covers 177 of the Clean Air Act's list of 187 air toxics plus diesel particulate matter. For 133 of these air toxics (those with health data based on chronic exposure) the assessment includes estimates of cancer or non-cancer health effects including non-cancer health effects for diesel particulate matter.

EPA develops NATA in cooperation with state and local environmental agencies, which provide key information about air toxics emissions. The assessment estimates that in most of the United States people have a lifetime cancer risk from air toxics between 1 and 25 in a million. This means that out of one million people, between 1 and 25 people have increased likelihood of developing cancer as a result of breathing air toxics from outdoor sources, if they were exposed to 1999 levels over the course of their lifetime (70 years).

The assessment estimates that most urban locations have an air toxics lifetime cancer risk greater than 25 in a million. Risk in transportation corridors and some other locations is greater than 50 in a million. In contrast, one out of every three Americans (330,000 in a million) will develop cancer during a lifetime, when all causes (including exposure to air toxics) are taken into account.

The second NATA expands on EPA's first national-scale assessment with a more complete emissions inventory and the latest health effects information. The first assessment, based on 1996 data, was release in 2002. The methods used for the assessments were peer-reviewed and endorsed by EPA's Science Advisory Board in 2001.

EPA plans to develop new national-scale assessments as inventory data from subsequent years become available. The next such analysis will focus on exposure and risks from 2002 emissions