Electrically charged filter materials have become quite common in many air cleaning applications. Several studies have shown that the standard filter tests will not reveal all phenomena which can take place when charged air filters are exposed to atmospheric aerosols. The objective of this study was to identify and characterize the outdoor and indoor air contaminants relevant for the behavior of charged filters. An equally important objective was to determine the major contaminants, which impact the charged filter media and what are the major mechanisms, i.e. why the airborne contaminants influence the performance of charged filter media.

This research project was divided into two phases. Phase I of this report focused on collecting the available information about the relevant outdoor and indoor air contaminants. The report includes information about the charged filter materials, information about the earlier studies on charged filters, and testing of the charged filters.

Phase II had two major tasks: filter material testing in the laboratory and field testing of both full-scale filters and filter materials in urban and suburban environments. In laboratory tests the effect of different factors (different aerosols, operating conditions, particle size and resistivity) on the degradation of efficiency of filter materials were tested.

This research project includes two seperate reports - one for each phase. The documents are delivered as a .zip file. You must have WinZip on your computer to open this file. The file is approximately 6.5MB in size.

Units: SI