section_subject: "National primary and secondary ambient air quality standards for PM"
cfr_reference: "40 CFR 50.7"
title_name: "Title 40"
title_subject: "Protection of Environment"
parts_covered: "Parts 50 to 51"
revised_date: "Revised as of July 1, 2019"
publication_date: "As of July 1, 2019"
contains_description: "Containing a codification of documents of general applicability and future effect"
publication_info: "Published by the Office of the Federal Register National Archives and Records Administration as a Special Edition of the Federal Register"
---
(a)The national primary and secondary ambient air quality standards for particulate matter are 15.0 micrograms per cubic meter (µg/m3) annual arithmetic mean concentration, and 65 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 of this part and designated in accordance with part 53 of this chapter; or
(2)An equivalent method designated in accordance with part 53 of this chapter.
(b)The annual primary and secondary PM2.5 standards are met when the annual arithmetic mean concentration, as determined in accordance with appendix N of this part, is less than or equal to 15.0 micrograms per cubic meter.
(c)The 24-hour primary and secondary PM2.5 standards are met when the 98th percentile 24-hour concentration, as determined in accordance with appendix N of this part, is less than or equal to 65 micrograms per cubic meter.