After a red alert was issued for the first time, many of Beijing's 22.5 million residents turned to humour to cope with the heavy smog.
Netizens wrote cynical comments, saying that under such heavy smog, besides wearing masks, the only job was to write jokes.
One online joke that has circulated widely is about a boss and an employee who is always late for work.
The boss asked the reason for the worker being late again. "Traffic? Something big at home? Any more excuses you can make up?" the boss said.
"Not at all. It is too blurry today. I couldn't find the company when I drove by," the employee replied.
Another blogger joked: "No wonder everybody wants to go to Beijing. No one can lose face there because no one's face can be seen under the heavy smog."
One said it is the best time for blind dates because you can never see your partner's face.
Although people joked around to lighten the heavy mood resulting from the smog, some said smog is a serious problem and should not be joked about.
"People's lives are at stake, but people are joking about that? Ridiculous!" one blogger wrote.
Another suggested that residents should protest about the smog.
"When the smog gets heavier, people only wear masks to cope with it, they don't fight to gain a clean environment," the netizen wrote.