The Clean Air Act as amended directs the Secretary of Health, Education, and Welfare to designate 'air quality control regions' to provide a basis for the adoption of regional air quality standards and the implementation of those standards. The Act stipulates that the designation of a region shall be preceded by consultation with appropriate State and local authorities. The report is intended to provide the basic background information needed for the consultation. In addition, on the basis of the information developed, the report proposes boundaries for the factors underlying the proposed boundaries. (Author)