High-resolution gamma ray spectroscopy has been used to obtain 214Bi/214Pb specific activity ratios from an extended series of high-volume air samples taken at a height of 20 m. Afternoon samples exhibited 214Bi/214Pb activity ratios that ranged from 0 to 2.5 with a mean value of 0.84¿0.04. Morning samples exhibited ratios that ranged from 0 to 1.6 with a mean value of 0.87¿0.03. Afternoon samples with ratios greater than 1.0 were associted with southwest winds and 214Pb specific activities less than 130 pCi/m3. Morning samples with ratios greater than 1.0 were associated in most cases with southwest winds and with 214Pb specific activities less than 220 pCi/m3. Afternoon 214Pb specific activity values ranged from 5 to 388 pCi/m3 with a mean of 91.7¿7.1 pCi/m3. Morning 214Pb specific activities ranged from 23 to 664 pCi/m3 with a mean of 224.2¿20.3 pCi/m3. An improved sampling system used for these measurements reduced the likelihood that observed abnormal activity ratios were artifacts of the sampling procedure.