(a) The national primary and secondary ambient air quality standards for particulate matter are 15.0 micrograms per cubic meter ([MICRO]g/m3) annual arithmetic mean concentration, and 65 [MICRO]g/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 of this part and designated in accordance with part 53 of this chapter; or (2) An equivalent
(a) The plan submitted by the Governor of Arkansas as follows: (1) April 23, 1981-submittal of the PSD Supplement Arkansas Plan of Implementation for Pollution Control (the "PSD Supplement") submitted April 23, 1981 (as adopted by the Arkansas Commission on Pollution Control and Ecology (ACPCE) on April 10, 1981); (2) June 3, 1988-submittal of revisions to the PSD Supplement (revised and adopted by the ACPCE on March 25, 1988); (3) June 19, 1990-submittal of revisions to the PSD Supplement (revised