Air pollution and temperature are associated with increased COVID-19 incidence: A time series study

Although COVID-19 is known to be caused by human-to-human transmission, it remains largely unclear whether ambient air pollutants and meteorological parameters could promote its transmission.

A retrospective study was conducted to study whether air quality index (AQI), four ambient air pollutants (PM_2.5, PM₁₀, NO₂ and CO) and five meteorological variables (daily temperature, highest temperature, lowest temperature, temperature difference and sunshine duration) could increase COVID-19 incidence in Wuhan and XiaoGan between Jan 26th to Feb 29th in 2020.

First, a significant correlation was found between COVID-19 incidence and AQI in both Wuhan (R²=0.13, p<0.05) and XiaoGan (R²=0.223, p<0.01). Specifically, among four pollutants, COVID-19 incidence was prominently correlated with PM_2.5 and NO₂ in both cities. In Wuhan, the tightest correlation was observed between NO₂ and COVID-19 incidence (R²=0.329, p<0.01). In XiaoGan, in addition to the PM_2.5 (R²=0.117, p<0.01) and NO₂ (R²=0.015, p<0.05), a notable correlation was also observed between the PM₁₀ and COVID-19 incidence (R²=0.105, p<0.05). Moreover, temperature is the only meteorological parameter that constantly correlated well with COVID-19 incidence in both Wuhan and XiaoGan, but in an inverse correlation (p<0.05).

AQI, PM_2.5, NO₂, and temperature are four variables that could promote the sustained transmission of COVID-19.