Evaluating test method of air cleaning devices for ozone removal (ASHRAE RP-1579)

As awareness of the adverse health effects of ozone and its byproducts increases, a dedicated filtration system that removes ozone from ambient air has become a required or preferred component of building ventilation systems. A test method that can provide accurate information on the performance and service life of ozone removal devices is key to their wide application. This study investigates the temporal change of ozone removal efficiency of air cleaning devices that use activated carbon and proposes a prolonged test protocol called "Ozone Stress Test"; it compares this new test protocol to the protocol described in ANSI/ASHRAE Standard 145.2-2016. Results show that activated carbon-based devices had a high degradation rate at the beginning of exposure to ozone or exposure to significantly increased ozone, so a short test (i.e., 1-h initial efficiency test and 4-h capacity test in Standard 145.2) overestimated filter performance. Filter capacity at 95% breakthrough could not be measured using the Standard 145.2 method or the prolonged test method because the filters had exceedingly low degradation rates after few hours' exposure to ozone. However, the average degradation rate during the capacity test can serve as an indicator of filter capacity.