Size distribution of atmospheric giant particles

Abstract

The size distribution of atmospheric giant particles in the range 5–100 μm radius was measured at three locations in Washington State using a rotary inertial impactor. The size distribution was continuous at the different locations. A significant change in the slope of the dN dlog r vs. r plot of the size distribution generally occurred between 30 and 40 μm radius. The slope B ( dN dlog r = Ar −B ) in the 5–25 μm radius range averaged 2.3 while in the 40 to 100 μm radius range B averaged 6.7. A complete atmospheric aerosol size distribution for the 0.01–100 μm radius range was obtained by combining thermal precipitator (0.01–1 μm) and inertial impaction (5–100 μm) data. It followed from the calculation of the atmospheric aerosol mass distribution (assuming spherical particles of unit density) that approximately 20 per cent of the total mass was in particles of less than 1 μm radius, 35 per cent in the 1–10μm range, 45 per cent in the 10–50 μm range, and less than 1 per cent in the greater than 50 μm radius range.