In current practice, EPA interprets the CAA and its amendments as requiring it to set NAAQS for each criteria pollutant independently from one another. Although the committee does not believe that the science has evolved to a sufficient extent to permit development of multipollutant NAAQS, it would be scientifically prudent to begin to review and develop NAAQS for related pollutants in parallel and simultaneously. Such a practice would facilitate the assessment of the commonality of sources, exposures, and effects among the pollutants, as well as the development of multipollutant AQMPs as recommended in Recommendation Three. Although such a change will require a transition period to be accomplished, it is not unprecedented and should be implemented expeditiously. (Earlier criteria documents address PM and SO2 at the same time, for example.) Thus, we recommend the following:
The criteria document and staff paper processes should be modified so that a simultaneous review of multiple interrelated pollutants could be developed in these documents. The interrelated NAAQS could then be considered in concert.
Coordinated recommendations should be made to the EPA administrator with respect to modifications of the existing NAAQS so that new or modified NAAQS could be simultaneously promulgated.
The implementation plans and attainment deadlines to address these NAAQS should be developed in a coordinated fashion to enable the development of multipollutant AQMPs.
In the current program to reduce emissions of HAPs from stationary sources, EPA is directed to undertake an assessment of residual risk following implementation of MACT and, on the basis of that assessment, decide whether additional controls are necessary. This program is getting under way somewhat slowly, the first completed assessment (on coke oven emissions) is expected in 2004. There are two key ways in which this process can be enhanced:
The assessment of residual risk is challenging and time consuming. Nevertheless, given the importance of these assessments, EPA should move to accelerate this process to address an increased number of assessments in the years to come. To the extent that EPA is challenged to enhance resources to support risk assessments, residual risk assessments should be enhanced.