The mechanisms of inactivation of aerosolized bacteriophage phiX174 in atmospheres containing ozone, cyclohexene, or ozonized cyclohexene were studied by using 32P-labelled phage. The inactivation of the aerosolized phage in clear air or in air containing cyclohexene is due to damage of the protein coat since the deoxyribonucleic acid (DNA) extracted from the inactivated phage retains its biological activity. Inactivation of the phage in air containing ozonized cyclohexene is due both to protein and DNA damage. Sucrose gradient analysis shows that aerosolized inactivated phiX174 releases unbroken DNA. In contrast, the DNA from phage phiX174 inactivated by ozonized cyclohexene is broken. The inactivation of aerosolized phage phiX174-DNA was studied in the same atmospheres using 32P-labelled DNA. phiX174-DNA aerosolized in clear air or air containing cyclohexene at 75% r.h. is inactivated by a factor of 2 in 30 min. The inactivated DNA is broken. Ozone as well as ozonized cyclohexene inactivates KNA very fast causing breaks in the molecule. This is in contrast with the intact bacteriophage in which ozone does not produce breaks in the DNA.

In the absence of ozone the OAF concentration was always low. In the presence of ozone the OAF concentration was dependent on wind direction. At the selected microthread exposure sites air from areas with high traffic intensity contributed more to OAF production than air from industrial areas. OAF production is probably related to the nature of hydrocarbons in the air.

The inactivation of aerosolized Escherichia coli by ozone, cyclohexene, and ozonized cyclohexene was studied. The parameters for damage were loss of reproduction and introduction of breaks in the deoxyribonucleic acid (DNA). Aerosolization of E. coli in clean air at 80% relative humidity or in air containing either ozone or cyclohexene hardly affected survival; however, some breaks per DNA molecule were induced, as shown by sucrose gradient sedimentation of the DNA. Aerosolization of E. coli in air containing ozonized cyclohexene at 80% relative humidity decreased the survival by a factor of 103 or more after 1 h of exposure and induced many breaks in the DNA.