A golfer plays on a hazy day at Pine Valley Golf Club on the outskirts of Beijing on Oct. 6, 2013
Chinese vacationers who used the weeklong National Day holiday to visit the capital would have taken nothing home except sooty photos and hacking coughs, because of smog that was unusually heavy even for Beijing.
Over the weekend, air readings of health-threatening particles known as PM2.5 peaked at 436, with 300 being the threshold regarded as hazardous. Pollution was so bad that flights were canceled and highways closed.
[WSJ]