Predicting Performance of Combination Particulate/Gaseous Contaminant Air Filters in the Highway and Street Traffic Environment filters

Automotive cabin filters of the “combo” type are intended to remove both aerosols and gaseous contaminants from air entering the climate control system. We analyze the performance of two filters of this type, using published values for the concentration of gaseous contaminants found in highway and street traffic. Using existing expressions for the performance of activated carbons, including the effects of contaminant concentration, flow rate and carbon bed depth, we calculate retentivity and breakthrough time for benzene and carbon tetrachloride at street-level concentrations. The calculated factors are compared to published test data on similar filters.