posted on 2007-08-01, 00:00authored byChristopher M. Walker, GwangPyo Ko
Ultraviolet (UV) germicidal air disinfection is an engineering
method used to control the airborne transmission of
pathogenic microorganisms in high-risk settings. Despite
the recent emergence of respiratory viral pathogens such
as SARS and avian influenza viruses, UV disinfection of
pathogenic viral aerosols has not been examined. Hence,
we characterized the UV disinfection of viral aerosols
using the bacteriophage MS2, adenovirus, and coronavirus.
Our objectives were to characterize the effect of
nebulization and air sampling on the survival of important
viral pathogens, quantitatively characterize and estimate
the UV susceptibility of pathogenic viral aerosols, and evaluate
the effect of relative humidity (RH) on the susceptibility
of viral aerosols, to 254 nm UV−C. The viruses were
aerosolized into an experimental chamber using a six-jet
Collison nebulizer, exposed to 254 nm UV, and sampled using
an AGI-30 liquid impinger. Both the MS2 and adenovirus
aerosols were very resistant to UV air disinfection, with a
reduction of less than 1 logarithm in viable viral aerosols
at a UV dose of 2608 μW s/cm2. The susceptibility of
coronavirus aerosols was 7−10 times that of the MS2
and adenovirus aerosols. Unlike bacterial aerosols, there
was no significant protective effect of high RH on UV
susceptibility of the tested viral aerosols. We confirmed
that the UV disinfection rate differs greatly between viral
aerosols and viruses suspended in liquid.