Infectivity of airborne SARS-CoV-2 could decrease by 90% within 20 minutes of exhalation

Press release issued: 28 June 2022

The SARS-CoV-2 virus can lose 90% of infectivity when in aerosol particles within 20 minutes, according to new University of Bristol findings. The study, published in the journal of the Proceedings of the National Academy of Sciences (PNAS), is the first to investigate the decrease in infectivity of SARS-CoV-2 in aerosol particles over periods from seconds to a few minutes. The aim of the study was to explore the process that could change viral infectivity over short timescales following exhalation.

Using a novel instrument called CELEBS (Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate), the team were able to probe the survival of SARS-CoV-2 in laboratory generated airborne particles and examine how temperature and humidity drive changes in infectivity, from timescales spanning five seconds to 20 minutes. The same experiment was carried out comparing four different SARS-CoV-2 variants, including Alpha and Beta.

Results from the team’s experiments found a significant loss in infectivity within the first ten minutes of aerosol particle generation that is strongly dependent on the environmental relative humidity, but not temperature. This effect did not alter across the different SARS-CoV-2 variants.

Read the full University of Bristol news item

'The dynamics of SARS-CoV-2 infectivity with changes in aerosol microenvironment' by Jonathan P. Reid, Andrew D. Davidson, Allen E. Haddrell et al in PNAS [open access]