Implications of the Proposed 24-Hour Primary PM₁₀Standard

This paper describes the influence of sampling frequency on the probability of attaining the proposed 24-hour primary PM10 standard and illustrates a method to compare the stringency of the proposed PM10 statistical standard and the existing total suspended particulate (TSP) 24-hour primary deterministic standard. Assuming that attaining or exceeding a standard on a given day is a binomial event, equations are presented to describe the attainment probability for TSP and PM10 It is shown that the PM10 sampling frequency leading to the highest attainment probability depends on the level of pollution' at the site being considered. Curves are presented that show the PM10 and TSP expected exceedances that result in equivalent attainment probability. To illustrate the procedure for comparing stringency, the frequency distributions for PM10 and TSP at five selected urban sites are presented and the nonattainment probabilities are compared.