New limits for fine particles established in the USA - Infrastructure & Cities. New limits on the concentration of fine particles allowed in America have been approved.
Average annual concentration of particulates within the borders of each state must not exceed 9 micrograms'(mcg) cubic permeter of air. Until now this limit was set at 12 mcg. The lung health association had called for the limits to be lowered to 8 mcg and the EPA has accepted their request.