Effect of ozone and open air factor against aerosolized Micrococcus luteus

Because of increased concerns over failures in cleaning, the role of bioaerosols, and the environmental and clinical persistence of pathogens, the evaluation of novel decontaminants is increasingly important. The bactericidal properties of open air factor (OAF; a collection of highly reactive chemical species) were identified in the 1970s; however, the potential practical applications of artificially generated OAF have been considered only recently. In this study, the effects of OAF against Micrococcus luteus were investigated. OAF was generated and distributed in a bioaerosol test chamber by delivery of monoterpenes into ozonated air (0.1 ppm) at concentrations of 2.0 (high), 0.75 (medium), or 0.3 (low) mgm(-3) h(-1). M. luteus was aerosolized, and the number of culturable survivors was determined after 2, 5, 10, 20, and 60 min. Culturable bacteria were enumerated by aerobic plate counts in all-glass impinger fluid. Data were analyzed for statistical significance using one- or two-way analyses of variance. When aerosolized bacteria were exposed to ozone alone (0.05, 0.1, and 2 ppm), a significant (up to 3-log) reduction was observed at all concentrations, and the effect was time dependent. When exposed to the cyclic monoterpene alone, there were no significant differences between test samples and controls. When exposed to OAF (high and medium concentrations in 0.1 ppm ozone) there were significant differences after 20 min. These reductions were significantly greater than those achieved with ozone alone at 0.1 ppm. OAF is potentially an effective antibacterial agent that can reduce the microbial load in air. Because the technology uses reaction compounds naturally found in the environment, risks to health may be lower than those associated with ozone or other gaseous treatments. However, this hypothesis needs further investigation.