15A NCAC 02D .0410      PM2.5 PARTICULATE MATTER

(a)  The national primary ambient air quality standards for PM2.5 shall be 12.0 micrograms per cubic meter (µg/m³) annual arithmetic mean concentration and 35 µg/m³ 24-hour average concentration measured in the ambient air as PM2.5 (particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers) by either:

(1)           A reference method based on appendix L to 40 CFR Part 50 and designated in accordance with 40 CFR Part 53; or

(2)           An equivalent method designated in accordance with 40 CFR Part 53.

(b)  The primary annual PM2.5 standard shall be deemed met when the annual arithmetic mean concentration, as determined in accordance with Appendix N of 40 CFR Part 50, is less than or equal to 12.0 µg/m³.

(c)  The primary 24-hour PM2.5 standard shall be deemed met when the 98^th percentile 24-hour concentration, as determined in accordance with Appendix N of 40 CFR Part 50, is less than or equal to 35 µg/m³.

History Note:        Authority G.S. 143-215.3(a)(1); 143-215.107(a)(3);

Eff. April 1, 1999;

Amended Eff. September 1, 2015; January 1, 2010;

Readopted Eff. January 1, 2018.