Red light spells danger

"My friends and I have started to make jokes along the lines of 'Right now, it's healthier to smoke in Beijing than to breathe the air,'" said Camille Chanlair, a French national who has lived in the city since 2008. "They all avoid going out when they see the pollution. Some have bought air purifiers," he added.

"This is no joke, people! This is serious stuff. You should not be outside right now with your children. Everyone should be taking it easy and avoid going outside," wrote Richard Saint Cyr, a general practitioner at a private hospital in Beijing, in a warning posted on his micro blog before he left work on Saturday evening.

Beijing hospitals reported a rise in the number of young patients seen for respiratory complaints over the weekend. [Photo provided for China Daily]

Saint Cyr, who has lived in China for six years, said his clinic has a good air filter system. His 200-square-meter home is also equipped with three air purifiers. "Honestly, with this high level (of pollution) even three purifiers won't really be effective. But at least I can close my bedroom door overnight," said the US national.

Zhang Bo, general manager of Beijing Jijian Science & Technology Development Co, said the three air purifiers at his home in Beijing are so overloaded that the red lights (indicating heavy pollution) can't be disarmed.

"It usually takes each machine an average of one hour to purify the air (in one room). When that's done, the red light turns green. Now, it stays red all the time," he said, adding that the pollution is so bad that he won't venture out of doors if he can avoid it.

Saint Cyr said he has seen an unusually high number of people arriving at the clinic complaining of bad coughs and breathing and pulmonary problems. Most feel better after being treated with cough syrup, but the doctor emphasized that the best treatment is to avoid exposure to the pollutants.

"At these levels, people of all ages should really avoid going outside, if possible. These types of pollution spikes can be deadly for very sick and fragile people who are already weak from illness. Anyone with a normal cold or flu will find it much harder to recover quickly in this polluted atmosphere," he said.

He recommended N95 filter respirators, a type of mask designed to combat PM2.5 and intended for those with no alternative to going outdoors. "They definitely stop PM2.5. The definition of N95 literally means it filters 95 percent of particulate matter — as small as PM0.3 microns, much smaller than PM2.5."

Unsurprisingly, sales of N95 masks surged tenfold on Friday and Saturday compared with the daily average, according to data provided by Taobao and Tmall, two online marketplaces that together hold more than 70 percent of China's online retail market. Local media in Beijing also reported that the capital's pharmacies have almost sold out of face masks, PM2.5-proof or not.

Saint Cyr emphasized that children and the elderly are especially vulnerable to spikes in air pollution and suggested that all school systems create air pollution "action plans" based on the science once the official hourly monitoring of PM2.5 begins nationwide.