15A NCAC 02D .0410 is proposed for amendment as published in 29:20 NCR 2337-2338 as follows:

15A NCAC 02D .0410	PM2.5 PARTICULATE MATTER
(a)  The national primary ambient air quality standards for PM2.5 particulate matter are: 
(1)	15.0 micrograms per cubic meter (ug/m3), annual arithmetic mean concentration; and
(2)	35 micrograms per cubic meter (ug/m3), 24-hour average concentration.
PM2.5 are 12.0 micrograms per cubic meter (ug/m[3]) annual arithmetic mean concentration and 35 ug/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 C.F.R. Part 50 and designated in accordance with 40 C.F.R. Part 53; or
(2) 	An equivalent method designated in accordance with 40 C.F.R. Part 53.
These standards are attained when the annual arithmetic mean concentration is less than or equal to 15.0 ug/m3 and when the 98th percentile 24-hour concentration is less than or equal to 35 ug/m3, as determined according to Appendix N of 40 CFR Part 50.
(b) The primary annual PM2.5 standard is met when the annual arithmetic mean concentration, as determined in accordance with appendix N of 40 C.F.R. Part 50, is less than or equal to 12.0 ug/m[3].
(b)  For the purpose of determining attainment of the standards in Paragraph (a) of this Rule, particulate matter shall be 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 of 40 CFR Part 50 and designed according to 40 CFR Part 53; or
(2)	an equivalent method designed according to 40 CFR Part 53.
(c) The primary 24-hour PM2.5 standard is met when the 98[th] percentile 24-hour concentration, as determined in accordance with appendix N of 40 C.F.R. Part 50, is less than or equal to 35 ug/m[3].

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.

