Health & Medicine, UK (Commonwealth Union) – The significance of fresh air in combatting the potency of viral diseases has long been pinpointed by researchers. Quite often a well-known factor has been that fresh air helps reduce viral diseases as opposed to remaining in a contained space with an infected individual.
Scientists from the University of Bristol have made significant discoveries regarding the loss of infectivity in airborne viruses. Their findings, recently published in the Journal of the Royal Society Interface, highlight the role of cleaner air in killing the virus more rapidly and emphasize the importance of opening windows, which may have greater significance than previously believed.
In the study, which represents the first examination of differences in airborne stability among various variants of SARS-CoV-2 inhalable particles, researchers from Bristol’s School of Chemistry revealed that the virus has exhibited reduced capability to survive in the air as it has evolved from the original strain to the ‘Delta’ variant.
Dr. Allen Haddrell, the lead author of the study who is also a Senior Research Associate at the University of Bristol, School of Chemistry, indicated that aerosol particles released when infected individuals breathe, speak, or cough can transmit viruses. However, the mechanisms underlying why and how viruses lose infectivity once they circulate within these airborne particles have been the subject of extensive debate.”
To conduct their research, the team utilized a state-of-the-art bioaerosol technology instrument called CELEBS (Controlled Electrodynamic Levitation and Extraction of Bioaerosols onto a Substrate). This instrument enabled them to investigate the survival of different SARS-CoV-2 variants within laboratory-generated airborne particles that simulate exhaled aerosols. Over a 40-minute period, they assessed the way atmospheric factors like temperature, humidity, particle composition, as well as the presence of acidic vapors like nitric acid affected virus infectivity.
By manipulating the gaseous content of the air, the team confirmed that the virus’s aerosol stability is influenced by the alkaline pH of the aerosol droplets containing the virus. Crucially, they observed that each variant of SARS-CoV-2 exhibits different stabilities when airborne, and these stabilities are correlated with their sensitivities to alkaline pH conditions.
The elevated pH of exhaled SARS-CoV-2 virus droplets is likely a key factor contributing to the loss of infectiousness. Therefore, the less acidic the air is, and the more alkaline the droplet, the faster the virus gets distroyed. The significance of opening windows is underscored, as fresh air with lower carbon dioxide levels reduces the acid content in the atmosphere, resulting in a significantly faster inactivation of the virus.
Dr Haddrell also indicated that the outcomes of the study demonstrate that the elevated pH of exhaled aerosols contributes to the reduction of viral infectivity. As a result, any gas that impacts the pH of aerosols could potentially influence the duration of viral viability in the air. For instance, gases such as bleach release acidic vapors that may enhance the stability of SARS-CoV-2 in the aerosol phase. Conversely, gases like ammonia, which emit alkaline vapors, might have the opposite effect, potentially reducing the virus’s stability in aerosols.
The results gave valuable details into why and how aerosolized viruses infectivity was lost, forming conditions for the design of new strategies to lower risk.
Jonathan Reid, who is Director of Bristol Aerosol Research Centre as well as Professor of Physical Chemistry in the School of Chemistry at the University of Bristol, and a corresponding author as well says “There are numerous factors that affect the transmission of airborne viruses, and these are often confounded with physical and environmental parameters that can affect viral longevity in the aerosol phase such as temperature, relative humidity, air movement and UV light.” He further indicated that the discoveries they have made expand their knowledge regarding the impact of environmental factors on the airborne stability of SARS-CoV-2 and other viruses. This newfound understanding will enable them to develop improved safety measures and mitigation strategies aimed at reducing the transmission of diseases. Moving forward, they plan to delve deeper into the role of pH by investigating the influence of carbon dioxide on the risk of SARS-CoV-2 transmission.
