40 CFR 50, App L

40 CFR 50, App L

Determination of Ambient PM2.5

This method provides for the measurement of the mass concentration of particulate matter with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers (PM2.5) in ambient air over a 24-hour period for purposes of determining attainment and maintenance of the primary and secondary national ambient air quality standards for particulate matter specified in 40CFR §50.6 and 40CFR §50.13. The measurement process is nondestructive, and the PM2.5 sample can be subjected to subsequent physical or chemical analyses.