Regulations last checked for updates: May 17, 2024

Title 40 - Protection of Environment last revised: May 15, 2024
Appendix - Table C-5 to Subpart C of Part 53—Summary of Comparability Field Testing Campaign Site and Seasonal Requirements for Class II and III FEMs for PM 10-2.5 and PM 2.5
Candidate method Test site A B C D
PM 2.5Test site location areaLos Angeles basin or California Central ValleyWestern city such as Denver, Salt Lake City, or AlbuquerqueMidwestern cityNortheastern or mid-Atlantic city.
Test site characteristicsRelatively high PM 2.5, nitrates, and semi-volatile organic pollutantsCold weather, higher elevation, winds, and dustSubstantial temperature variation, high nitrates, wintertime conditionsHigh sulfate and high relative humidity.
Class III Field test campaigns (Total: 5)Winter and summerWinter onlyWinter onlySummer only.
Class II Field test campaigns (Total: 2)Site A or B, any seasonSite C or D, any season.
PM 10-2.5Test site location areaLos Angeles basin or California Central ValleyWestern city such as Las Vegas or PhoenixMidwestern cityLarge city east of the Mississippi River.
Test site characteristicsRelatively high PM 2.5, nitrates, and semi-volatile organic pollutantsHigh PM 10-2.5 to PM 2.5 ratio, windblown dustSubstantial temperature variation, high nitrates, wintertime conditionsHigh sulfate and high relative humidity.
Class III Field test campaigns (Total: 5)Winter and summerWinter onlyWinter onlySummer only.
Class II Field test campaigns (Total: 2)Site A or B, any seasonSite C or D, any season.
authority: Sec. 301(a) of the Clean Air Act (42 U.S.C. sec. 1857g(a)), as amended by sec. 15(c)(2) of Pub. L. 91-604, 84 Stat. 1713, unless otherwise noted
source: 40 FR 7049, Feb. 18, 1975, unless otherwise noted.