id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-271980-8x5g8r7c	Yao, Ye	Ambient nitrogen dioxide pollution and spread ability of COVID-19 in Chinese cities	2020-09-30		.txt	text/plain	3478	172	50	When examining the correlation between NO 2 and R 0 of COVID-19, we estimated the associations of NO 2 concentration with R 0 both inside and outside Hubei province (r & p) in the same period by using multiple linear regression models after controlling for temperature and relative humidity (as covariates in the regression model) separately. We also examined the corresponding temporal associations between NO 2 and R 0 of COVID-19 across the different cities inside and outside Hubei Province using multiple linear regression models after controlling for temperature and relative humidity separately. The cross-sectional analysis indicates that, after adjustment for temperature and relative humidity, R 0 was positively associated with NO 2 concentration at city level (meta χ 2 =10.18, J o u r n a l P r e -p r o o f p=0.037) (Figure 3) .	./cache/cord-271980-8x5g8r7c.txt	./txt/cord-271980-8x5g8r7c.txt