Neutralization of spore aerosol releases is critical in countering bioterrorism. As a possible spore aerosol neutralization method that avoids the use of chemicals, we investigate the mechanical instabilities of the bacterium cell envelope in air as bacteria are passed through aerodynamic shocks. To carry out this fundamental investigation, an experimental impactor system is used to collect the spores after they pass through a controlled shock, and a detailed computational study is carried out to determine the impactor operating conditions that lead to bacterial break-up. Specifically, the bacteria experience relative deceleration because of sharp velocity changes in the aerodynamic shock created in the experimental impactor system. Computational model results indicate that B. atropheus spores require a critical acceleration of 3.9-16 x 10(9) m/s(2) compared to 3.0 x 10(8) m/s(2) for vegetative E. coli to break-up consistent with our experimental findings. Our experimental results indicate that the fraction of cells surviving an aerodynamic shock with a maximum acceleration of 5.9 x 10(9) m/s(2) is f(l) = 0.030 +/- 0.010. (C) 2010 Elsevier Ltd. All rights reserved.