Removal of ozone on clean, dusty and sooty supply air filters

The removal of ozone (O3) on supply air filters was studied. Especially, the effects of dust load, diesel soot, relative humidity (RH), and exposure time on the removal of O3 were investigated. Some loss of O3 was observed in all the filters, except in an unused G3 pre-filter made of polyester. Dust load and quality influenced the reduction of O3; especially, diesel soot removed O3 effectively. Increasing the RH resulted in a larger O3 removal. The removal of O3 was highest in the beginning of the test, but it declined within 2 h reaching almost a steady state as the exposure continued. However, the sooty filters continued to remove as much as 25–30% of O3. Up to 11% of O3 removed participated in the production of formaldehyde. Small amounts of other oxidation products were also detected.