Chronic exposure to ambient air pollution has been related to increased mortality in the general population [1]. After the outbreak of the SARS-CoV-2 pandemic in 2019, there has been a fast proliferation of epidemiological studies linking ambient air pollution to coronavirus disease 2019 (COVID-19) incidence or adverse prognosis [2]. It has been hypothesised that ambient air pollution might increase human vulnerability to viruses by reducing immune defences, promoting a low-level chronic inflammatory state, or leading to chronic diseases [3]. Most studies have applied ecological designs, and failed to account for key individual-level or area-level determinants of COVID-19 spread or severity, such as demographic characteristics of the studied populations, socioeconomic or clinical susceptibility, and area-level proxies of disease spread such as mobility or population density [4].

长期暴露于环境空气污染与普通人群死亡率增加有关[1]。2019 年 SARS-CoV-2 大流行爆发后，将环境空气污染与 2019 年冠状病毒病 (COVID-19) 发病率或不良预后联系起来的流行病学研究迅速增加 [2]。据推测，环境空气污染可能通过降低免疫防御、促进低水平的慢性炎症状态或导致慢性疾病来增加人类对病毒的脆弱性[3]。大多数研究都应用了生态设计，未能解释 COVID-19 传播或严重程度的关键个体水平或地区水平决定因素，例如所研究人群的人口学特征、社会经济或临床易感性、