Impact of Relative Humidity on COVID-19 Incidence

Abstract

Introduction: The issue of the influence of external factors such as meteorological conditions on the dynamics of the coronavirus pandemic is extremely relevant, since understanding of physical foundations of any process helps predict its results in specific conditions and, to a certain extent, manage it. Objective: In order to assess the effect of relative humidity on the incidence of COVID-19, we analyzed opinions of the international scientific community about the nature and degree of the influence of meteorological conditions on COVID-19 incidence rates in humans. Materials and methods: We developed an original method of determining the periods of time when the air humidity level influenced disease rates, establishing the lag and the power of influence of the relative air humidity on the infection process and course of the disease. To eliminate the effect of confounders on research results, we applied the author’s method of estimating the conditional incidence as the difference between the theoretical and observed rates. The article presents the results of analyzing the correlation between relative humidity and COVID-19 incidence rates in 19 regions of the Russian Federation. Without exception, all the equations contained two or three extrema of the incidence in time, at which air humidity had the greatest impact on its rates. We associate these extrema with the time of getting infected and the time of disease manifestation and they enable us to quantitatively predict the latent period of this infectious disease in different atmospheric conditions. Conclusion: The observed correlations demonstrate relative humidity levels posing higher and lower risks of getting infected with COVID-19 in various regions of the Russian Federation. By means of mathematical methods, we confirmed the hypothesis about the persistence of SARS-CoV-2 in the environment for more than two weeks.