Image for post
Image for post

Recent research shows that the novel coronavirus can stay in the air for some time, but whether it is likely to cause infection is very conditional.

This depends on the size of virus particles. Droplets, which are the larger ones (over 5 micrometres), don’t travel further than 1 metre and quickly fall on a surface. They are released through coughing, sneezing or speaking. Aerosols are smaller than 5 micrometres, can travel up to 4 metres and can stay in the air for up to 3 hours, but their concentration would be dangerous only in certain cases.

What are those cases? Can I walk into a viral cloud and get sick? Chinese research found SARS-CoV-2 aerosols in two Wuhan hospitals. High concentrations were only detected in confined spaces, such as unventilated toilets or crowded areas. In contrast, concentrations were very low in ventilated patients’ rooms. Another study found an additional hotspot: areas where medical staff removed their contaminated protective equipment. As to the outdoors, such as parks, a Dutch study using computational fluid dynamics simulation observed particle clouds created by walkers, runners and cyclists and suggested that people should keep a 4, 9 or 20-metre distance to avoid aerosols. However, the research did not look at viral levels in aerosols and could not inform about specific SARS-CoV-2 infection risk. The above studies of ventilated indoor spaces suggest that aerosols would carry even less viral particles in the open than indoors. …

Image for post
Image for post

Answer: Depending on the material, the virus causing COVID-19 can stay on surfaces for days. Recent research suggests that SARS-CoV-2 could last longer on some surfaces than previously thought and that crucially, it could stay viable on the outer layer of surgical masks for up to seven days.

How do we know this? Researchers conducted a lab experiment and dropped viral samples on different surfaces in a room temperature (22 C) environment with 65% relative humidity. They found that the virus stopped being infectious

  • on tissue paper and printing paper after 3 hours,
    on wood and clothing after 1 day
  • on smooth, shiny surfaces, like glass and banknotes after 3…

Image for post
Image for post

French researchers have conducted an experiment and found that only temperatures higher than on an extremely hot summer day could kill the 2019-nCoV virus. Researchers at Aix-Marseille University “cooked” the virus for different periods of times and at different temperatures. They found that either 1 hour at 60 ℃ or 15 minutes at 92 ℃ was the best method to inactivate the virus.

Does this mean we have to expect the same levels of infections in the summer?
Scientists can’t give a definite answer. Although earlier varieties of coronaviruses proved to be seasonal, currently we have a highly susceptible population that has not developed the necessary immunity yet. …


Endre Szvetnik

I’m Senior Editor at working with researchers to tell their stories to the wider public

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store