Pressure Correction is Not Required for Particulate Matter Sampling.

The Environmental Protection Agency's Reference Methods for determining particulate matter as PM10 require pressure corrections before comparison to their National Ambient Air Quality Standards. No chemical, physiological, or toxicological basis exists for correction for particulate sampling when results are expressed in weight per unit volume (fxg/m3). The implications of misapplying pressure corrections are at least twofold: a) exposure assessment comparisons at different elevations, using EPA generated data, do not use equivalent doses; and b) cities at higher elevations are held to a more stringent compliance standard.