Solar UV-B/A radiation is highly effective in inactivating SARS-CoV-2

  1. Fabrizio Nicastro
  2. Giorgia Sironi
  3. Elio Antonello
  4. Andrea Bianco
  5. Mara Biasin
  6. John R. Brucato
  7. Ilaria Ermolli
  8. Giovanni Pareschi
  9. Marta Salvati
  10. Paolo Tozzi
  11. Daria Trabattoni
  12. Mario Clerici

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Abstract

Solar UV-C photons do not reach Earth’s surface, but are known to be endowed with germicidal properties that are also effective on viruses. The effect of softer UV-B and UV-A photons, which copiously reach the Earth’s surface, on viruses are instead little studied, particularly on single-stranded RNA viruses. Here we combine our measurements of the action spectrum of Covid-19 in response to UV light, Solar irradiation measurements on Earth during the SARS-CoV-2 pandemics, worldwide recorded Covid-19 mortality data and our “Solar-Pump” diffusive model of epidemics to show that (a) UV-B/A photons have a powerful virucidal effect on the single-stranded RNA virus Covid-19 and that (b) the Solar radiation that reaches temperate regions of the Earth at noon during summers, is sufficient to inactivate 63% of virions in open-space concentrations (1.5 × 10 3 TCID 50 /mL, higher than typical aerosol) in less than 2 min. We conclude that the characteristic seasonality imprint displayed world-wide by the SARS-Cov-2 mortality time-series throughout the diffusion of the outbreak (with temperate regions showing clear seasonal trends and equatorial regions suffering, on average, a systematically lower mortality), might have been efficiently set by the different intensity of UV-B/A Solar radiation hitting different Earth’s locations at different times of the year. Our results suggest that Solar UV-B/A play an important role in planning strategies of confinement of the epidemics, which should be worked out and set up during spring/summer months and fully implemented during low-solar-irradiation periods.

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  1. Version published to 10.1038/s41598-021-94417-9
  2. Version published to 10.1101/2020.06.03.20121392v3 on medRxiv
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    No key resources detected.

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  4. Version published to 10.1101/2020.06.03.20121392v2 on medRxiv
  5. Version published to 10.1101/2020.06.03.20121392v1 on medRxiv