key: cord-0939209-q581v2sy
authors: Yao, Ye; Pan, Jinhua; Liu, Zhixi; Meng, Xia; Wang, Weidong; Kan, Haidong; Wang, Weibing
title: Temporal Association between Particulate Matter Pollution and Case Fatality Rate of COVID-19 in Wuhan
date: 2020-07-15
journal: Environ Res
DOI: 10.1016/j.envres.2020.109941
sha: be88be39b2b5b24106f788c0d5346833c35aeaac
doc_id: 939209
cord_uid: q581v2sy

The coronavirus (COVID-19) epidemic reported for the first time in Wuhan, China at the end of 2019, which has caused 4,648 deaths in China as of July 10, 2020. This study explored the temporal correlation between the case fatality rate (CFR) of COVID-19 and particulate matter (PM) in Wuhan. We conducted a time series analysis to examine the temporal day-by-day associations. We observed a higher CFR of COVID-19 with increasing concentrations of inhalable particulate matter (PM) with an aerodynamic diameter of 10 μm or less (PM(10)) and fine PM with an aerodynamic diameter of 2.5 μm or less (PM(2.5)) in the temporal scale. This association may affect patients with mild to severe disease progression and affect their prognosis.

This study was sponsored by the Bill & Melinda Gates Foundation

COVID-19 is a rising infectious disease that poses a great challenge to global public health. As of 10 July 2020, there were 85,445 confirmed cases in China and 4,648 deaths occurred. Wuhan, the epicenter of the outbreak, have accounted for 58.9% of the total number of cases and 83.2% of the deaths in China. Cui et al. 1 have found that air pollution can affect the case fatality rate (CFR) of severe acute respiratory syndrome (SARS). The COVID-19 is a respiratory disease with a specific level of likeness to SARS, and there could likewise be a connection between the CFR and air pollution 2 .

Fattorini et al. 3 demonstrated that long-term air-quality data had a significant association with the confirmed number of COVID-19 cases in 71 provinces of Italy, suggesting a favorable context for the spread of the SARS-CoV-2 due to air pollution.

Coccia et al. 4 came to a similar conclusion that polluted cities in Italy had a very high number of infected people of COVID-19. Since the association between air pollution and COVID-19 infections has been well described, this study aims to investigate the temporal association between the CFR of COVID-19 and PM concentration (the primary air pollutant in China) in Wuhan.

We conducted a study to examine the association of PM 2.5 /PM 10 concentrations and the CFR of COVID-19 in Wuhan of China.

The data of confirmed cases and deaths on COVID-19 were obtained from the 

We conducted a time series analysis to examine the association of PM 2.5 and PM 10 concentrations with the CFR of COVID-19 in Wuhan by using multivariate linear regression, with adjustment for temperature, relative humidity, concentrations of sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ), carbon monoxide (CO), and ozone (O 3 ).

Because of the lockdown of Wuhan and the short study period, we assumed very little changes on either the total number of the population or its age and gender composition. We also examined the lag effects and patterns of PM 2.5 and PM 10 on the CFR of COVID -19 by analyzing the association between the CFR and single-day daily average PM concentrations on the current day (lag0) and up to 5 days (lag1-lag5) before the date of infection.

As illustrated in Fig.1A , there was a delay of approximately 21 days between the peak of newly diagnosed cases and the peak of daily COVID-19 deaths, which was in line with our prior estimation. From January 19 to March 15, 2020, the daily CFR μg/m 3 ); the mean daily temperature and relative humidity were 7.18°C and 81.37%, respectively (range, 1.8°C-18.7°C and 59.0%-93.0%). As shown in Fig.1B , we found that the daily concentrations of PM 2.5 and PM 10 changed synchronously and were very similar. We also found that the two air pollutants and the daily CFR exhibited great 8 similarity with respect to their temporal variation curves. Further, an obvious time lag existed between daily CFR and daily PM 2.5 and PM 10 concentrations (Fig. 1B) .

After adjusting for temperature and relative humidity, SO 2 , NO 2 , CO, and O 3 , we found that the CFR was positively associated with all the lag0-lag5 concentrations of and PM 10 , respectively. To explore the impact of meteorology on PM, we did a further analysis, and found temperature, relative humidity and rainfall held no significant correlations with PM (r<0.24, p>0.07).

In this study, we found that the daily concentrations of PM 2.5 and PM 10 changed synchronously, which might be explained by the fact that PM 10 contained also fine particles (such as PM 2.5 ). In the further time series analysis to examine the association of PM 2.5 and PM 10 concentrations with the CFR of COVID-19 in Wuhan, with adjustment for temperature, relative humidity, concentrations of SO 2 , NO 2 , CO, and O 3 , we found COVID-19 deaths were highly correlated with PM 2.5 and PM 10 concentrations, a trend which was also observed for other respiratory diseases 8 . In addition, Bontempi 9 concluded that PM 10 seemed not to affect COVID-19 infections, in accord with our study (r<0.15, p>0.28).

Worldwide, most COVID-19 deaths have occurred in the elderly especially those with underlying health problems, which potentially make them more vulnerable to air pollution. PM 2.5 , PM 10 , and CFR significantly decreased from January 19 to March 15, 2020, which might be partially attributed to effectively reduce human activities and improved medical support in Wuhan by Perm et al. 10 . Patients who died from COVID-19 were likely to be critically ill and most of them had been treated in negative pressure wards 11 . In these wards, air circulation should be limited to avoid potential further COVID-19 transmissions and outdoor PM couldn't affect patients in this stage. Therefore, we speculate that the early exposure to PM may play a very important role, rather than in the period after hospitalization. We theorize that the effect of PM 2.5 and PM 10 on COVID-19 passing primarily influences patients who progress from gentle to serious infection through increasing system inflammation and oxidative stress, which would decrease cardiopulmonary functions 12 . This process could account for only PM 2.5 and PM 10 during the first several days of infection showing a significant association with the CFR.

We found a positive relationship between PM 2.5 and PM 10 

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

Similarity in Case Fatality Rates (CFR) of COVID-19/SARS-COV-2 in Italy and China

Role of the chronic air pollution levels in the Covid-19 outbreak risk in Italy

Factors determining the diffusion of COVID-19 and suggested strategy to prevent future accelerated viral infectivity similar to COVID

Evolving epidemiology and transmission dynamics of coronavirus disease 2019 outside Hubei province, China: a descriptive and modelling study

COVID-19 illness in native and immunosuppressed states: A clinical-therapeutic staging proposal

Particulate air pollution and mortality in a cohort of Chinese men

First data analysis about possible COVID-19 virus airborne diffusion due to air particulate matter (PM): The case of Lombardy (Italy)

The effect of control strategies to reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China: a modelling study

Clinical course and mortality risk of severe COVID-19

We thank Liwen Bianji, Edanz Group China (www.liwenbianji.cn/ac), for editing the English text of a draft of this manuscript.

The authors declare no competing interests. 

☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:None