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 2.5 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.