The association of air quality and complex atmospheric oxidation chemistry in the dispersion and deposition of SARS-CoV-2-laden aerosols

Abstract

The present study investigates the effects of air pollution and climate factors on the acceleration of SARS-CoV-2 transmission and mortality. In particular, the correlations between O₃, NO₂, PM_2.5, PM₁₀ and SO₂ concentrations with daily number of infections and fatalities caused by the second wave of COVID-19 during the time period March–June 2021 in Indian cities with different climate zones are analyzed. The chemical transformations in the atmosphere that translated to dispersion of SARS-CoV-2 aerosols and their deposition in the respiratory system are studied. The results suggested that exposure to a higher level of O₃ may weaken the respiratory system, and therefore resistance against COVID-19 is suppressed. The infectious aerosols undergo reactive encounters with atmospheric oxidants, forming secondary aerosols before deposition in the lungs. The pulmonary epithelium is naturally protected against atmospheric O₃ and secondary aerosols by lung-lining fluids that contain ascorbic acid, AH₂ and other antioxidants. Since O₃ and COVID-19 infections showed a positive correlation, AH₂ and the underlying tissues will be the most affected. The mechanism for the interaction of O₃ with AH₂ is studied using quantum chemical methods. During this interaction, a persistent ozonide is formed in lung-lining fluids and this is acidified by the inhaled aerosols. Earlier epidemiological and toxicological studies revealed that this ozonide leads to the formation of cytotoxic free radicals that can cause oxidative stress during breathing. Thus, O₃ plays a significant role in the deposition of aerosols in the lungs. The results of this study add to prevailing evidence as well as providing new insights into the role of ambient O₃ in the dispersion and deposition of SARS-CoV-2 aerosols.