The efficacy of filtration for the control of ozone-derived secondary organic aerosols (SOA) in an air handling system that recirculates a large percentage of its air

Abstract

This study examined the impact of filtration on the concentration of secondary organic aerosols (SOA) derived from ozone (of outdoor origin) reacting with limonene (of indoor origin) within a recirculating air handling system that serviced an unoccupied, 236 m3 chamber configured to simulate a typical office. Although the pleated panel filter used was only moderately efficient (35% single-pass removal efficiencies for 100 nm particles), the presence of such a filter (new or used) resulted in SOA mass concentrations that were more than 5-times lower than when there was no filter in the system. When, instead, an activated carbon filter was used in the system, the concentration of ozone and SOA were even lower than when either a new or used panel filter was in the system. In other words, under conditions in which ozone drives the production of aerosols, activated carbon filters are more effective at reducing aerosol concentrations than moderately efficient particle filters.