EPA is concerned about the environmental and public health impacts of air toxics in local communities. In order to better assess air toxics risk, the Agency has developed a computer model known as ASPEN under its Cumulative Exposure Project to estimate ambient levels of toxic air pollutants nationally. To test the model, 1990 emissions data were used--the most recent and comprehensive information available at the time of the analysis. Emissions of air toxics have changed since that time. Since 1990, EPA has issued standards that are expected to reduce emissions of air toxics from stationary sources by over one million tons per year. Because these data are older and the model has certain assumptions and limitations, EPA strongly cautions against using the results of this modeling exercise alone to draw real-world conclusions about current local conditions. Providing the public with information they can use to protect the health and the environment of their communities is a guiding principle of EPA's work, but that information must be timely if it is to be valuable for characterizing current environmental conditions. This new national-scale air quality model, together with other models and air quality monitoring, will be useful tools in the future for better understanding the environmental and public health risks from toxic air pollution both nationally and locally. EPA is working with state and local agencies to update and improve this air toxics emissions information, and intends to use this model with 1996 data later this year to update national estimates of ambient air toxics levels.
Visit EPA's Cumulative Exposure Project website to learn more.
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