The committee recommends that column B indicating the capabilities of personal-exposure measurements, be eliminated, largely because it does not draw on NARSTO’s expertise. Furthermore, the committee finds that the material presented in column A may be better handled in the text, where some of the subtleties could be discussed. Indeed, the only measurements that can be considered fully routine are those of particle mass associated with a particular size cutoff and those of number of particles. Discussing this material in the text could provide an opportunity to indicate what the priorities should be for improvements in measurement technology.
There are two additional ways in which the response could be improved. First, the response calls for improvements in monitoring, emission-inventory development, and modeling, but it does not identify a need for laboratory research. Experiments in the laboratory help to improve the understanding of the chemical and physical mechanisms by which PM evolves in the atmosphere and provide critical input to models; this piece of a comprehensive research program should be mentioned. Second, there could be more discussion of why a mass-based standard may not lead to a reduction in the most toxic components of PM and how atmospheric scientists can assist the health-science community in addressing this topic.