Ambient Carbon Dioxide Concentration Correlates with SARS-CoV-2 Aerostability and Infection Risk

Abstract

Abstract An improved understanding of the underlying physicochemical properties of respiratory aerosol that influence viral infectivity may open new avenues to mitigate the transmission of respiratory diseases such as COVID-19. Previous studies have shown that a rapid increase in the pH of respiratory aerosols following generation due to changes in the gas-particle partitioning of pH buffering bicarbonate ions and carbon dioxide is a significant factor reducing viral infectivity. We show here that a significant increase in viral aerostability results from a moderate increase in the atmospheric carbon dioxide concentration (e.g. 1,800 ppm), an effect that is more marked than that observed for changes in relative humidity. We model the likelihood of COVID-19 transmission on the ambient concentration of CO2, concluding that even a moderate increase in CO2 concentration results in a significant increase in overall risk. These observations confirm the critical importance of ventilation and maintaining low CO2 concentrations in indoor environments for mitigating disease transmission. Moreover, the impact of CO2 concentration correlating with viral aerostability suggests increased risks of respiratory pathogen transmission will accompany increased ambient CO2 concentrations as our climate changes.