The Vienna University of Veterinary Medicine (Vetmeduni) presented a study this Monday in a statement explaining that the coronavirus can stay infectious up to 24 hours outdoors during the months of winter.
The research analyzes the effect of ultraviolet radiation (UV) that the sun emits on coronaviruses, both in surfaces as in aerosols, since it has the potential to make them harmless.
The sun reduces infections in summer
But it depends mostly on the place and season of the year: In Sao Paulo (Brazil), for example, “only one ten thousandth of all coronaviruses survive every day in the open air throughout the year, while in Reykjavik (Iceland) this strong influence only occurs in June and July”, reports the note.
To measure the relationship between solar radiation and the deactivation of COVID-19, scientists have combined satellite data on the amount of ultraviolet radiation reaching Earth with available information on the effectiveness of this type of radiation on coronaviruses.
According Alois Schmalwieser, the researcher who led the study, disinfection by solar radiation is “very effective in aerosols” in the open air, since it also has no alternative. “The virus is not very sensitive to temperature: it would be necessary 50 or 60 degree centigrade [para desactivarlo], temperatures that you only find in the desert “, explains the researcher.
In cases of infection of Person to personHowever, ultraviolet radiation would have little effect, since the virus transfer is much faster than deactivation.
Winter increases infections
During the colder months of the winter, When there are fewer hours of sunshine and clouds frequently cover the sky, the disinfecting effect of ultraviolet radiation is greatly reduced, especially in the Northern and central European countries.
According to the researchers’ estimates, if in April 2020 – just after the first wave of the pandemic – solar radiation had a great effect on the sterilization of the coronavirus throughout the European continent, this influence will be much less in December. “In countries like Portugal or Spain the difference will not be as great as in Vienna, where we have cloudy skies from November to February”, Schmalwieser clarifies.
Schmalwieser believes that the virus’s increased survivability outdoors during the winter months could be counteracted with longer stay indoors -where more infections occur-, since the cold makes people leave the house less.
The scientists’ next goal is to calculate the exact relationship between the number of infections and the effect of solar radiation.