January 5, 2017
"I made this earlier today - a bank of AQI400+ smog arriving in Beijing within the space of 20 minutes."
Via the NYT. ("The video was by taken by Chas Pope, a British worker, and posted on Monday, just as the city has been grappling with yet another extended bout of pollution... The past few weeks have been especially bad in Beijing. Officials declared a red alert for the city on Dec. 16, the most severe warning in a four-tier system, forcing older, high-emissions motor vehicles to stay off the road and schools to close. Hundreds of flights were canceled and highways were shut down because of low visibility.")