What environmental factors affect transmission of respiratory viruses?

In our latest GCHU Guest Blog, MSc in Evidence-Based Health Care Course Director and Kellogg Fellow Dr Annette Plüddemann explores the extent to which environmental factors affect the transmission of respiratory viruses.

Dr Annette Plüddemann

Course Director MSc in Evidence-Based Health Care and Kellogg College Fellow

Environmental factors such as temperature and humidity, climate and weather, pollution, and UV radiation can affect the transmission of respiratory viruses. Many studies have looked at what environmental factors might affect transmission of respiratory viruses and we conducted a comprehensive review of all the published studies.  We found 395 research studies and 86 reviews, and we summarised their findings.  Most of the research studies we found looked at the effect of environmental factors on the transmission of SARS-CoV-2 (241 studies), many looked at influenza (95 studies), but very few studies were published on other respiratory viruses (such as Respiratory Syncytial Virus, pneumonia, rhinovirus, and other coronaviruses). 

The studies and reviews reported that air pollution, wind speed, precipitation, season, and UV radiation affect the transmission of respiratory viruses. Cold and dry weather conditions were associated with a more rapid increase in SARS-CoV-2 infections, but despite the large number of studies published on SARS-CoV-2, there was very little detailed information on how environmental factors affect virus transmission. Air pollution was repeatedly associated with higher levels of respiratory disease, but there was very little data for identifying specific relationships between air pollutants and viral respiratory outcomes. Studies of influenza show that typically there is a mid-winter peak in both the Northern and Southern hemisphere, but more detailed information on environmental exposures is limited. For other viruses, very little information was available on the impact of the environment on transmission.

Overall, our research found that although many studies have been published, there is very little high-quality research providing detailed information that can inform public health advice about environmental influences and the risk of transmission of respiratory viruses.