a 24 hour collection period. Aerosols are collected upon a 10.16 cm diameter HEPA filter rated for 0.3 $\mu$m aerosol sizes and counted directly atop the top face of the detector. For the sake of these measurements, it was assumed that essentially all fission products in the air are attached to aerosols greater than this size. All filters analyzed with the n-type HPGe detector showed statistically significant peaks from the naturally produced airborne gamma-emitters, such as $^{7}$Be and $^{210}$Pb. Initial counting (within an hour after end of sampling) of filters also showed prominent peaks from the short-lived daughters of U-series $^{222}$Rn and Th-series $^{220}$Rn. Analysis of gamma ray peaks from short-lived Rn daughters could provide useful information with respect to collection of fission product nuclides, especially for short collection periods. The analysis procedure included several short counting intervals to quantify Rn daughter activities, followed by an overnight count to increase the possibility of detecting very small peaks, as may be expected from the first signs of fission product radionuclides from the damaged Japanese reactors. Filter exchanges were initially performed in 24 hour cycles. Sampling intervals were later extended to 2 or more days, one week, and eventually to one month 