2016: From space, the smog appears gray.
2016: Officials issued pollution alerts for more than 40 cities in northern China in mid-December 2016. During its latest bout of intense smog—which led to red alerts in more than 20 cities—authorities shut down schools and airports and told citizens to stay indoors, according to news reports.
2013: Residents of Beijing and many other cities in China were warned to stay inside in mid-January 2013 as the nation faced one of the worst periods of air quality in recent history. The Chinese government ordered factories to scale back emissions, while hospitals saw spikes of more than 20 to 30 percent in patients complaining of respiratory issues, according to news reports.