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

Area of Science:

• Environmental Science
• Virology
• Epidemiology

Background:

• Solar UV-C photons possess germicidal properties but do not reach Earth's surface.
• The impact of UV-B and UV-A photons on viruses, especially single-stranded RNA viruses like SARS-CoV-2, is understudied.
• Understanding environmental factors influencing viral spread is crucial for public health.

Purpose of the Study:

• To investigate the virucidal effects of UV-B and UV-A solar radiation on the SARS-CoV-2 virus.
• To correlate solar UV radiation levels with COVID-19 mortality patterns.
• To assess the potential role of solar radiation in the seasonality of COVID-19.

Main Methods:

• Measured the action spectrum of SARS-CoV-2 (COVID-19) response to UV light.
• Analyzed solar irradiation data during the COVID-19 pandemic.
• Utilized worldwide COVID-19 mortality data and a "Solar-Pump" diffusive epidemic model.

Main Results:

• UV-B/A photons demonstrate a significant virucidal effect on the single-stranded RNA virus SARS-CoV-2.
• Summer noon solar radiation in temperate regions can inactivate 63% of SARS-CoV-2 virions in under 2 minutes.
• Observed global COVID-19 mortality seasonality correlates with varying UV-B/A solar radiation intensity across latitudes.

Conclusions:

• Solar UV-B/A radiation plays a key role in reducing SARS-CoV-2 viability in the environment.
• The distinct seasonality of COVID-19 mortality in temperate versus equatorial regions is likely influenced by solar UV radiation.
• Strategies for epidemic control should consider seasonal solar UV-B/A levels, implementing measures during periods of low solar irradiation.