The CASAC panel did not develop a detailed description of particulate-matter research needs, but it described the following general research areas to be of highest priority (CASAC 1997):

• Effects of long-term exposures and relative contributions of short-term peak and cumulative exposures to long-term health outcomes

• Mechanisms by which particulate matter could contribute to life shortening, daily mortality and morbidity

• Linkages between particulate-matter data from outdoor monitors and actual personal exposures

• Particulate-matter classes and physical-chemical characteristics associated with response pathways and potency

• Extent to which particulate matter causes health effects independent of other pollutants

No second rank of priorities was given by the CASAC panel. Several other research topics were mentioned, but there was no consensus on their priorities.

The panel also recommended the following important concepts:

• Interdisciplinary collaboration and integration of efforts

• Research training

• International cooperation

The CASAC panel also recommended that in determining research needs, EPA would benefit from more consideration of the technical feasibility and time requirements of conducting proposed research. Some of the research suggested in EPA's 1996 draft research-needs document was judged by CASAC as not feasible for technological reasons. The panel recommended that the time required to fill critical information gaps should be estimated, and that the research-needs document would benefit from the placement of research in a time context, with the 2002 review of the particulate-matter NAAQS as one benchmark.