The Influence of Natural Radon Occurrence on the Severity of the COVID-19 Pandemic in Germany: a Spatial Analysis

Abstract: The exposure to naturally occurring, radioactive noble gas radon is known to cause permanent damage in lung tissue. Lung diseases and prior radiation of lung tissue have been identified as contributing to a severe progression of COVID-19. As the COVID-19 pandemic also showed within Germany largely unexplained high spatial variation of mortality and infection rates, it was suggested that the increased exposure to radon gas damages the lung to a degree, that amplifies an infection with SARS-CoV-2 and causes a more severe progression of COVID-19, which could show as an increase of infection rates and a high ratio of fatalities per infection, also known as case fatality ratio, in regions of high radon occurrence. Three different time periods were analysed at a district level, to test for spatial correlations of case fatality ratio and infection rate to radon occurrence in Germany, defined as radon soil gas concentration. In each period case fatality ratios and infection ratios of the total population, population equal to or greater than 60 years and population below 60 years were tested for correlation to mean age, mean income, mean living space, and mean radon soil gas concentration. Consequently, a possible indication of a weak positive spatial correlation between case fatality ratio and radon occurrence was demonstrated. Additionally, a weak but significant spatial correlation between COVID-19 infection rates and radon occurrence was revealed. An additional spatial regression analysis supported the suspected associations and radon soil gas concentration could explain parts of the spatial variations of infection rates and case fatality ratios. As the study was limited to a spatial analysis and did not include the temporal dimension, a more sophisticated methodology was suggested. Further limitations of the data and methodology raised the need for additional research to support the findings and accept the hypothesis of spatial correlation between COVID-19 and radon exposure was pointed out.