ABSTRACT
UV radiation from the sun is the primary germicide in the environment. The goal of this study was to estimate inactivation of viruses by solar exposure…
… Sunlight or, more specifically, solar UV radiation (UV) acts as the principal natural virucide in the environment. UV radiation kills viruses by chemically modifying their genetic material, DNA and RNA. The most effective wavelength for inactivation, 260 nm (55), falls in the UVC range, so-named to differentiate it from near-UV found in ground-level sunlight, i.e., the UVB and UVA portions of the spectrum, 290 to 320 nm and 320 to 380 nm, respectively (51). Nucleic acids are damaged also by UVB and UVA but with lower efficiency than by UVC radiation
… The overwhelming majority of published information on UV inactivation of viruses has been based upon exposure to UVC (UV254) radiation from a low-pressure mercury vapor (germicidal) lamp, with the primary emission at 254 nm. However, UV254 is not found in the sunlight that reaches the earth's surface; the ground-level virucidal solar UV wavelengths fall above 290 nm (16). Fortunately, the primary photochemical processes that damage the viral DNA or RNA occur at all the solar UV wavelengths, varying only in the efficiency of the different wavelengths (55). Since there are few published data that describe the survival of viruses, and none for threat viruses, following exposure to solar UV radiation, extrapolation from UV254 data will be required for most viruses. This extrapolation can be made using wavelength dependence (action spectrum) data.
… The action spectra of virus inactivation were found to be similar for all viruses regardless of genome type. Thus, one composite action spectrum was used to represent all viruses.
