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expert reaction to study looking at how temperature and population density influences transmission of SARS-CoV-2

A study, published in Proceedings of the National Academy of Sciences (PNAS), looks at how environmental conditions potentially influence transmission of SARS-CoV-2.


Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, University of Leicester, said:

“This type of environmental-incidence correlation is not new – some of us have been writing about this for years in relation to influenza, which is a lipid-enveloped virus, like coronaviruses:

“But what many of these earlier studies have failed to highlight is that where transmission occurs by short-range aerosols, e.g. over the 1 m ‘garlic breath’ conversational distance, the viruses are exhaled/inhaled very quickly – much too quickly for environmental parameters to impact much on the airborne virus survival.

“This study highlights this aspect by showing that measures to reduce interpersonal contact and crowding are much more important than any variation in environment parameters, to control the spread of lipid-enveloped viruses, like SARS-COV-2.

“This is also partly why, despite being on very well ventilated planes (with ventilation rates of as much as 30 air changes per hour), interpersonal aerosol transmission can still (though more rarely) occur over short conversational (< 1m) distances – because the exhalation/inhalation of these airborne viruses occurs too quickly for the ventilation to remove them completely from people’s breathing zones.”



‘Temperature and population density influence SARS-CoV-2 transmission in the absence of non-pharmaceutical interventions’ by Thomas P. Smith et al. is published in Proceedings of the National Academy of Sciences (PNAS):


All our previous output on this subject can be seen at this weblink:


Declared interests

None received.

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