key: cord-1040813-teaisbqj
authors: Ran, Jinjun; Zhao, Shi; Han, Lefei; Qiu, Yulan; Cao, Peihua; Yang, Zuyao; Chong, Marc K C; Yang, Lin; Wang, Maggie H; He, Daihai
title: Effects of Particulate Matter Exposure on the Transmissibility and Case Fatality Rate of COVID-19: A Nationwide Ecological Study in China
date: 2020-08-10
journal: J Travel Med
DOI: 10.1093/jtm/taaa133
sha: e12c959c37147bc44cec16ee68dae119f8065c9c
doc_id: 1040813
cord_uid: teaisbqj

nan

This study aims to examine whether the particulate matter is an environmental determinant of COVID-19 transmissibility or its crude case fatality rate (CFR) in China.

We obtained the data of COVID-19 cases and deaths for 303 Chinese cities during December 2019 -March 2020 from the Chinese provincial health agencies and China National Health Commission. The basic reproductive number (R 0 ) was calculated to quantify the COVID-19 transmissibility for each city by the Euler-Lotka equation, 3 

regression analysis, the relationships between COVID-19 transmissibility (R 0 ) and three PM categories in both univariable and multivariable models were not statistically significant ( Figure 1 ). However, all three PM categories were positively associated with the mortality risk of COVID-19 (Table 1) Cautions should be taken when interpreting the results. First, some confounders were not adjusted in this analysis, such as smoking prevalence, BMI distribution, the coverage of health insurance and local health expenditure due to data unavailability. We remarked the importance of controlling the unmeasured confounders. Our analytical framework can accommodate these confounders once they are available. Second, the prevalence of city-level comorbidities, especially cardiorespiratory diseases, could modify the association of the COVID-19 CFR with PM exposure. The prevalence might also mediate the association in partial since the PM exposure could amplify the risk of comorbidities. 9,10 However, these factors were not incorporated in the current analysis due to lack of data. Thus, the risk estimates of three PM metrics on the CFR could be only interpreted as the average total effects. Third, the ecological fallacy was inescapable, so that the population-level results cannot deduce to individuals. Fourth, we ignored the right-censoring situation in the crude CFR calculation since our study period was relatively long for infectious disease epidemics. Our analytical approach could be extended by incorporating the truncated or zero-

inflated likelihood framework to address the limitation. Last, for the dataset used in our analysis, the local and imported cases could not be disentangled in each city, which might cause a noise in the R 0 estimation. Nevertheless, the noise should be minor due to the early lockdown of Wuhan.

In summary, our study observed an ecological association of city-level COVID-19's CFR with PM exposure. More studies are warranted to further examine the potential effects of PM on the transmissibility, activity, and toxicity of the COVID-19 virus. 

Exposure to air pollution and COVID-19 mortality in the United States

How generation intervals shape the relationship between growth rates and reproductive numbers

Preliminary estimation of the basic reproduction number of novel coronavirus (2019-nCoV) in China, from 2019 to 2020: A data-driven analysis in the early phase of the outbreak

No Association of COVID-19 transmission with temperature or UV radiation in Chinese cities

A Re-analysis in Exploring the Association between Temperature and COVID-19 Transmissibility: An Ecological Study with 154 Chinese Cities

Air pollution and case fatality of SARS in the People's Republic of China: An ecologic study

Particulate matter and the airway epithelium: The special case of the underground?

Does air pollution contribute to travelers' illness and deaths?-evidence from a case report and need for further studies

Exposure to air pollution is associated with adverse cardiopulmonary health effects in international travellers