Headline: Air quality in Germany as a contributing factor to morbidity from COVID-19

Background: The SARS-CoV-2 virus has been spreading in Germany since January 2020, with regional differences in incidence, morbidity, and mortality. Long-term exposure to air pollutants as nitrogen dioxide (NO2), nitrogen monoxide (NO), ozone (O3), and particulate matter (<10µm PM10, < 2.5µm PM2.5,) has a negative impact on respiratory functions. We analyze the association between long-term air pollution and the outcome of SARS-CoV-2 infections in Germany. Methods: We conducted a cross-sectional study in Germany on county-level, investigating the association between long-term (2010-2019) air pollutant exposure and COVID-19 incidence, morbidity, and mortality rate during the rst outbreak of SARS-CoV-2. We used negative binominal models, including adjustment for risk factors (age, sex, days since rst COVID-19 case, population density, socio-economic and health parameters). Results: After adjustment for risk factors in the tri-pollutant model (NO2, O3, PM2.5) an increase of 1µg/m³ NO2 was associated with an increase of the need for intensive care due to COVID-19 by 4.2% (95% CI 1.011–1.074), and mechanical ventilation by 4.6% (95% CI 1.010–1.084). A tendency towards an association of NO2 with COVID-19 incidence was indicated, as the results were just outside of the de ned statistical signi cance (+1.6% (95% CI 1.000 -1.032)). Long-term annual mean NO2 level ranged from 4.6µg/m³ to 32µg/m³. Conclusions: Our results indicate that long-term NO2 exposure may have increased susceptibility for COVID-19 morbidity in Germany. The results demonstrate the need to reduce ambient air pollution to improve public health.