the invention provides devices and methods for sampling , detecting and / or characterizing particles . devices and methods of the invention , including particle samplers , impactors and counters , include a filter component for removing particles in the exhaust flow of the device , for example , to eliminate or minimize the potential for the device itself to provide source of particles in an environment undergoing particle monitoring . this aspect of the present devices and methods is particularly useful for monitoring particles in manufacturing environments requiring low levels of particles , such as cleanroom environments for electronics manufacturing and aseptic environments for manufacturing pharmaceutical and biological products .