Microbial aerosols: estimated contribution of combine harvesting to an airshed.

From plate counts of the airborne microorganisms in the downwind dust plume of operating grass-seed combines, the mean source concentrations were calculated to be 6.4 x 10 and 4.7 x 10/m, respectively, potentially accounting for at least 41.9% of the bacteria and 35.1% of the fungi in the airshed in the Willamette Valley, Oregon.