OAR 340-202-0060
Ambient Air Quality Standards: Suspended Particulate Matter
(1)
150 micrograms of PM10 per cubic meter of air as a 24-hour average concentration for any calendar day. This standard is attained when the expected number of days per calendar year with a 24-hour average concentration above 150 micrograms per cubic meter as determined in accordance with Appendix K of 40 CFR 50 is equal to or less than one at any site. Concentrations of the fraction of suspended particulate that is equal to or less than 2.5 microns in aerodynamic diameter in ambient air as measured by an approved method must not exceed:(2)
35 micrograms of PM2.5 per cubic meter of air as a 3-year average of annual 98th percentile 24-hour average values recorded at each monitoring site. This standard is attained when the 3-year average of annual 98th percentile 24-hour average concentrations is equal to or less than 35 micrograms per cubic meter as determined in accordance with Appendix N of 40 CFR 50.(3)
12 micrograms of PM2.5 per cubic meter of air as a 3-year average of the annual arithmetic mean. This standard is attained when the annual arithmetic mean concentration is equal to or less than 12 micrograms per cubic meter as determined in accordance with Appendix N of 40 CFR 50.
Source:
Rule 340-202-0060 — Ambient Air Quality Standards: Suspended Particulate Matter, https://secure.sos.state.or.us/oard/view.action?ruleNumber=340-202-0060.