In this report, Research Topic 4 has been divided into Subtopic 4a, which addresses the development and evaluation of source-oriented models, and Subtopic 4b, which addresses receptor-oriented models. Because EPA monitoring is not expected to provide adequate data for model evaluation, the committee has increased its resource estimate for source-oriented models from the original estimate in its first report. Subtopic 4b shows the same amount of resources for receptor-oriented model development that was presented in Research Topic 3 of the first report.
Research Topic 9 retains the three subtopics from the first report. However, Subtopic 9c ("Human Clinical") was expanded by reallocating, from Research Topic 3 of the first report, $1.5 million per year for 3 years beginning in 2001 for the development of advanced analytic methods for monitoring biological responses to toxic components of particulate matter.
It is important to recognize that many parts of the research effort will continue to depend heavily upon data developed in technical programs maintained by the government in areas that fall outside the scope of the research activities recommended by the committee. Examples of such activities are testing of emissions sources, compilation of emissions inventories, and much of the collection of ambient data to support testing and evaluation of air-quality models. These technical programs may be carried out by government regulatory or research programs at the federal, state, or local level, or by nongovernmental organizations (see Table 3.2).