Fig. 3.
Variation per unit and 95% confidence intervals, (A) NO2, (B) PM2.5, and (C) PM10. The variation per unit (VPU) = [exp(variable coefficient) – 1] × 100%. The VPU can be interpreted as the percentage increase in the number of COVID-19 cases associated with a 10-μg/m3 increase in long-term average NO2 and PM2.5. The VPU from the main analysis was adjusted for confounding factors. In the sensitivity analyses, we omitted each confounding factor separately, and used seasonal air pollutant concentrations.
COVID-19, coronavirus disease 2019; PM2.5, particulate matter ≤2.5 μm; PM10, particulate matter ≤10 μm; NO2, nitrogen dioxide.