A group of over 100 exercisers wearing masks do brisk walking amid heavy smog in Shenyang, Northeast China's Liaoning province on Monday evening, November 9, 2015. The city reported severe air pollution on Sunday, with the reading of PM2.5 at 7 a.m. was 864. Environmental protection bureau of the city urged residents to avoid outdoor activities and to consider wearing protective masks on its official page on Sina Weibo, China’s version of Twitter. (Photo/CFP)
