| 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. |
