When pollution blows in from the heavily industrial neighboring towns and cities, it builds up and, in windless days, gets trapped over the capital.

In fact, this is not the first time bad air has bedeviled Beijing. I remember one day last year when the U.S. embassy's air monitoring system reported the pollution level as "crazy bad."

What can we Beijing residents do about it?

Wear face masks? Unless you use heavy-duty ones, I am told, they do not really make much difference.

Turn on air-purifiers full blast? We've never used one at home, although my friends swear they help.

"The truth is there isn't a lot people can do about ambient air pollution," said Deborah Soligsohn, an environment and energy specialist at the World Resources Institute, a U.S. based think tank.

"Ambient air pollution is not nearly as large a health risk as more immediate forms of air pollution. Tobacco is a much larger killer, and indoor air pollution from poorly ventilated wood and coal fires has traditionally been a much larger killer in the developing world. Smoky restaurants and bars can have levels as high as these recent air pollution numbers."

I know a few expat friends who have decided to relocate out of Beijing and were mainly turned off by its bad air.

"What did you think of Beijing?" I asked David Van Dyke, who lived and worked in Beijing for nearly seven years before relocating to Canada last year.

"Mostly liked it, save for the Internet (censorship) and pollution," he said.

Meantime, some residents have resorted to humor and sarcasm online to vent their frustration.

"I love my city, but I refuse to be a human vacuum cleaner," netizens re-tweeted on Weibo, China's microblogging social media. "We want clean air, and we want to breathe freely."

Others posted pictures wearing face masks of various shapes and designs.

A page of Sohu.com featured a section covered with haze, with a note saying the headlines have been obscured by a massive smog. "Click on it, and it will clear up." Once it cleared it, the title read: "We live in a "toxic gas.'"

"Don't worry," Henry Ngo posted on my Facebook page. "Smokers are inhaling worst air than this. And they did not die immediately!"

Is this now the new "normal"?

Soligsohn, who lived in Beijing for 14 years, does not think so.

"This is a confluence of bad events," she assured me. "Pollution is definitely a problem. It hasn't gone away, but there is no reason to believe an extreme reading is anything other than an extreme."

There seems to be no quick solution.

"This is complex and takes time, but the work has begun," Soligsohn added.