In this February 21, 2017 photo, a woman wearing a mask walks to a subway station during the evening rush hour in Beijing. Yet the city’s average reading of the tiny particulate matter PM2.5 – considered a good gauge of air pollution – is still seven times what the World Health Organization considers safe. A group of Chinese lawyers is suing the governments of Beijing and its surrounding areas for not doing enough to get rid of the smog. (Photo by Andy Wong/AP Photo)
