In December, Shanghai experienced its worst pollution since the government began tracking air quality data, with levels of PM2.5 hitting as high as 602. Airline flights were canceled and people were forced indoors. “Beijing used to be more of an issue in terms of air quality, but over the past year we are hearing more candidates expressing concern over it in Shanghai too,” Emma Wang, a Shanghai-based consultant with talent management company Egon Zehnder International Inc., said by e-mail. “The air quality issue is causing increasing concern but not to the extent that candidates make career decisions because of this.”

http://www.bloomberg.com/news/2014-09-29/smog-clouds-shanghai-s-drive-to-become-global-financial-center.html