Effects of particulate matter exposure on the transmissibility and case fatality rate of COVID-19: A Nationwide Ecological Study in China

Authors’ Contributions: J. Ran and S. Zhao conceived the study and carried out the analysis. L. Han and P. Cao collected the data. J. Ran and S. Zhao drafted the first manuscript and discussed the results. Y. Qiu, Z. Yang, M.K.C. Chong and L. Yang contributed to the interpretation of the results. M. H. Wang and D. He supervised the project. All authors critically read and revised the manuscript and gave final approval for publication. Funding: D. He was supported by General Research Fund (Grant Number 15205119) of the Research Grants Council (RGC) of Hong Kong, China and an Alibaba (China) - Hong Kong Polytechnic University Collaborative Research project. Disclaimer: The funding agencies had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication. Acknowledgements: Conflict of Interests: D. He received support from an Alibaba (China) - Hong Kong Polytechnic University Collaborative Research project. (COVID-19) pandemic has become one of the worst global health crises in the recent 50 years. Emerging studies from Italy and the United States suggested that particulate matter (PM) could impact the transmissibility and risk of death of COVID-19. 1,2 The generality of these findings remains unsettled in other regions. 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 with a Gamma-distributed generation interval having mean (±SD) values of 5.5 (±3.3) days. 3,4 The crude CFR was calculated as the ratio of cumulative confirmed deaths over confirmed cases during the period. Environment monitoring data during the same period of each city were obtained from the China National Environmental Center, including PM 10 (particulate matter with an aerodynamic diameter less than 10 μm) and PM 2.5 (particulate matter with an aerodynamic diameter less than 2.5 μm). The concentration of PM 10-2.5 was calculated using PM 10 and PM 2.5 concentration data. We then computed mean concentrations of the three PM categories during the period. City-level meteorological data were obtained from the National Meteorological Data Center. The demographic information was extracted from the China Statistical Yearbook (2019 version), including the percentage of the population age ≥ 65 years, sex ratio, percentage of the population with high education, gross domestic product (GDP) per city, and population density. We s by We carried fitting with a scheme