The use of penetration (leaking) curve parameters for the characterization of respira tor adsorbent filters has been demonstrated. The penetration curve parameters can be calculated if the concentration in the effluent air from the filter is continuously monitored during the filter testing. From the penetration curve parameters it is possible to predict the service time as a function of concentration of the pollutants, air flow and filter dimensions, and the amount taken up by the filter at any time during the filtration process can be calculated.