Inactivation of virus-containing aerosols by ultraviolet germicidal irradiation

The increasing incidence of infectious diseases has prompted the application of Ultraviolet Germicidal Irradiation (UVGI) for the inactivation of viruses. This study evaluates UVGI effectiveness for airborne viruses in a laboratory test chamber by determining the effect of UV dosage, different nucleic acid type of virus (single-stranded RNA, ssRNA; single-stranded DNA, ssDNA; double-stranded RNA, dsRNA; and double-stranded DNA, dsDNA), and relative humidity on virus survival fraction after UVGI exposure. For airborne viruses, the UVGI dose for 90% inactivation was 339-423 mu Wsec/cm(2) for ssRNA, 444 - 494 mu Wsec/cm(2) for ssDNA, 662 - 863 mu Wsec/cm(2) for dsRNA, and 910-1196 mu Wsec/cm(2) for dsDNA. For all four tested, the UVGI dose for 99% inactivation was 2 times higher than that for 90% inactivation. Airborne viruses with single-stranded nucleic acid ( ssRNA and ssDNA) were more susceptible to UV inactivation than were those with double-stranded ones ( dsRNA and dsDNA). For all tested viruses at the same inactivation, the UVGI dose at 85% RH was higher than that at 55% RH, possibly because water sorption onto a virus surface provides protection against UV-induced DNA or RNA damage at higher RH. In summary, UVGI was an effective method for inactivation of airborne virus.