Some critics have pointed fingers at China's top two oil firms, China National Petroleum Corp and China Petrochemical Corporation, saying the companies' outdated production technologies yield large quantities of substandard, high-polluting gas fuel that contains five times as much sulphur as gas products in the United States.

"The smoggy weather has sounded an alarm to oil companies," said Yue Xin, a specialist on fuel and emissions studies with the Chinese Research Academy of Environmental Sciences. "It's high time to improve fuel quality in order to cut emissions."

Meanwhile, concerned Beijingers have moved their brainstorming sessions to cyberspace. If Pan's proposal for a Clean Air Act is adopted, netizens say the new law should include clauses providing for "car-free days" in times of smog, higher standards for vehicle fuel, stricter restrictions on industrial and exhaust gas emissions, and more effective protection for the public.

Schools and kindergartens should close on smoggy days, one male Sina Weibo user suggested.

Adequate protection should also be given to those who work outdoors, like traffic police, the user noted.

"None of the police officers I saw on the street were wearing a mask," he wrote. "They said they were not allowed."

Moreover, the Weibo user said residents should be allowed to stay home on smoggy days, even if they will have to make up for the missed work hours on weekends.

"The Clean Air Act should start with a car ban," said Wang Lifen, a former CCTV reporter and prolific microblogger. "Everyone -- senior officials and VIPS included -- should take buses and subways instead of private cars."

Wang said she walks to her office every day and would be happy to travel around the city by bus or bike.

Five days of thick fog caused thousands of deaths from bronchitis, asthma and pneumonia in Britain in December 1952, prompting the government to pass the first Clean Air Act in 1956, which introduced smokeless zones and cleaner fuels to reduce pollution.