Use of Assessment Results
|The results of EPA's national-scale assessments provide important information to help EPA and its partners at the State, local and Tribal level continue to develop and implement various aspects of the air toxics program. They have not been used directly to regulate sources of air toxics emissions. While regulatory priority setting is informed by EPA's national-scale assessments, risk-based regulations are based on more refined and source-specific data and assessment tools. More specifically, the 1999 assessment results will help:
One of EPA's original goals for conducting national-scale assessments was to track trends and measure progress in the air toxics program. However, due to the extent of improvements in our methodology for the 1999 assessment (e.g., almost double the number of point sources in the emissions inventory, inclusion of over 100 additional air toxics, updated unit risk estimates), it is not meaningful to compare the 1999 assessment with the 1996 assessment. This is because any change in emissions, ambient concentrations, or risks may be due to either improvements in methodology or to real changes.