Comparison of Air Sampling Methods for Aerosolized Spores of B. anthracis Sterne

Bacillus anthracis Sterne spores were aerosolized within a chamber at concentrations ranging from 1×103 to 1.7×104 spores per cubic meter of air (particles (p)/m3) to compare three different sampling methods: Andersen samplers, gelatin filters, and polytetrafluoroethylene (PTFE) membrane filters. Three samples of each type were collected during each of 19 chamber runs. Chamber concentration was determined by an aerodynamic particle sizer (APS) for the size range of 1.114–1.596 μm. Runs were categorized (low, medium, and high) based on tertiles of the APS estimated air concentrations. Measured air concentrations and recovery efficiency [ratio of the measured (colony forming units (CFU)/m3) to the APS estimated (particles/m3) air concentrations] for the sampling methods were compared using mixed-effects regression models. Limits of detection for each method were estimated based on estimated recovery efficiencies. Mean APS estimated air concentrations were 1600 particles/m3, 4100 particles/m3, and 9100 parti...