PM(10) PM(2.5)/PM(1) DATA FROM A TRICHOTOMOUS SAMPLER/

As part of an effort to determine whether 1 mu m or 2.5 mu m is the be tter choice for a new fine particulate matter standard, Professor Virg il A. Marple of the University of Minnesota developed a high volume tr ichotomous (PM(10)/PM(2.5)/PM(1)) sampler. Two of these samplers were used to obtain particulate matter (PM) samples at a site located in Ph oenix, Arizona, from May 1995 through October 1995. All filter samples were analyzed for mass concentrations and a few for elemental and che mical compositions. Relative fractions were determined for PM(10), PM( 2.5), PM(1), PM(2.5-10), and PM(1-2.5). Calculations were made to eval uate how coarse and fine mode aerosol contributed to the intermediate size range. Results indicated that most of the PM(10) in Phoenix was c oarse mode PM (windblown dust), which was also a primary contributor t o PM(2.5).