or Will We See a Separate Secondary

摘要

The indicator for the 1971 secondary PM NAAQS was "total suspended participates" (TSP), the averaging time was 24 hours, the level was 150 pg/m3, and the form was not to be exceeded more than once a year (see Table 1). This first (and last) separate secondary PM NAAQS was based on the first Air Quality Criteria for Paniculate Matter (PM CD), published by the Department of Health, Education, and Welfare in 1969.2