Evaluation of a high-efficiency, filter-bank system

In USA, after the 2001 bioterrorist attack, filtration efficiencies have been evaluated at three US. Postal Service (USPS) facilities. New ventilation and filtration systems (VFSs) including HEPA filters were used to provide an optimal filtration efficiency (at least 99,97 %). In this paper the techniques used for measurement of particle concentration are described (use of optical particle counters GRIMM Type) and the results presented.