40 CFR Part 53, Table C-5
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
| Candidate method | Test site | A | B | C | D |
|---|---|---|---|---|---|
| PM 2.5 | Test site location area | Los Angeles basin or California Central Valley | Western city such as Denver, Salt Lake City, or Albuquerque | Midwestern city | Northeastern or mid-Atlantic city. |
| Test site characteristics | Relatively high PM 2.5, nitrates, and semi-volatile organic pollutants | Cold weather, higher elevation, winds, and dust | Substantial temperature variation, high nitrates, wintertime conditions | High sulfate and high relative humidity. | |
| Class III Field test campaigns (Total: 5) | Winter and summer | Winter only | Winter only | Summer only. | |
| Class II Field test campaigns (Total: 2) | Site A or B, any season | Site C or D, any season. | |||
| PM 10-2.5 | Test site location area | Los Angeles basin or California Central Valley | Western city such as Las Vegas or Phoenix | Midwestern city | Large city east of the Mississippi River. |
| Test site characteristics | Relatively high PM 2.5, nitrates, and semi-volatile organic pollutants | High PM 10-2.5 to PM 2.5 ratio, windblown dust | Substantial temperature variation, high nitrates, wintertime conditions | High sulfate and high relative humidity. | |
| Class III Field test campaigns (Total: 5) | Winter and summer | Winter only | Winter only | Summer only. | |
| Class II Field test campaigns (Total: 2) | Site A or B, any season | Site C or D, any season. |