From: Regulation
By Susan E. Dudley
Last January 14th, the Environmental Protection Agency published a final rule in the Federal Register updating the National Ambient Air Quality Standards (NAAQS) for particulate matter. The rule reduces by 20 percent the allowable annual concentrations of fine particles less than 2.5 micrometers in size (PM 2.5), from the current 15.0 micrograms per cubic meter (μg/m3) that was affirmed in 2006, to 12.0 μg/m3.