For the fourth time this year, a murky haze has descended over north China, leaving residents of Beijing choking on toxic smog. China's air hasn't been this bad since 1954, according to the state-run People's Daily newspaper.
In a remarkable record of dirty air, 24 out of January's first 29 days this year had air classified as hazardous. And the skies have still not cleared.
The Air Quality Index from the U.S. embassy, designed by the U.S. Environmental Protection Agency, shows that the concentration of fine particulate matter, known as PM 2.5, has been hovering at the top of the scale since last Friday. It's in a range described as "hazardous" and calls for protective measures to be taken.
Visibility is reduced to 100 yards in downtown Beijing. Travel has been disrupted with more than 100 flights cancelled, at a time when millions start the journey home for Chinese New Year.
The air is so bad that wealthy Chinese entrepreneur, Chen Guangbiao, is selling fresh air in soft drinks cans, similar to bottled drinking water. Each can is sold for 5RMB or about 80 cents. Chen is well known for his charitable donations and publicity stunts. He says he wants to stimulate awareness of environmental protection among government officials and citizens by selling the canned fresh air.
"If we don't pay attention to environmental protection, in 10 years every one of us will be wearing gas masks and carrying oxygen tanks on the streets," Cheng told ABC News. "By that time, my canned fresh air will be a necessity for household," he predicts.
The current blanket of smog has been blamed for a sharp rise in the number of respiratory illnesses, particularly among children and the elderly. A pediatric hospital in downtown Beijing has treated a record 9,000 children this month. They are mostly flu, pneumonia, bronchitis and asthma patients, according to Xinhua, the state news agency.
Masks have become the new fashion on Beijing's streets. The number of online searches for the word "mask" has jumped by 5,304.3 percent compared to last month, according to figures released by Taobao, the biggest online shopping site in China. There are more than 100,000 masks being sold every day this month in Beijing alone.
Ordinary medical masks do not provide enough protection. Some Beijing citizens have taken more serious measures by wearing gas masks. In one Beijing city office, as many as 20 workers wore the protective headgear at their desks, according to AFP.
Today by mid-morning, a text from the government was sent to millions of cell phones warning residents to stay indoors. Beijing environmental authorities temporarily shut down 103 high-emission factories on Tuesday and ordered 30 percent of government cars off the roads. Premier Wen Jiabao has spoken out publicly, calling for reduced emissions and increased environmental awareness. The measures will continue until Thursday, when weather forecasts predict strong wind will sweep into Beijing and blow away the smog.
The air pollution has also been one of the hottest topics being discussed on the internet.
Pan Shiyi, a celebrity real estate developer, and a deputy to the Beijing Municipal People's Congress, started an online poll Tuesday calling for "Clean Air Act" on Sina Weibo, China's Twitter. Within three hours, more than 25,000 web users responded with 99 percent in favor of his proposal. On the same day, Pan was criticized by citizens for continuing to operate a large construction site in the center of Beijing producing clouds of dust.