citizens to wear pollution masks as they stepped out of their homes; some residents wore gas masks as the normal masks were not adequate to provide protection.
Flights were cancelled because of poor visibility and the Beijing municipal government asked residents to stay indoors.At many parts of Beijing, a city of more than 20 million people, visibility was reduced to around 500 metres.
The US embassy – which has a pollution measuring mechanism installed -- reported a level of PM2.5, one of the worst pollutants, at 526 micrograms per cubic metre, or "beyond index"; it was more than 20 times higher than World Health Organisation safety levels for a 24-hour period.
The smog has also led to a surge in respiratory illnesses, particularly among children and the elderly.
According to state media report, a pediatric hospital in downtown Beijing has treated a record 9,000 children this month, mostly flu, pneumonia, tracheitis, bronchitis and asthma patients.
State media also reported that citizens had made an online demand for stricter anti-pollution law.
Pan Shiyi, a real estate developer and microblogger with 14 million followers, on Tuesday said he is planning to propose a Clean Air Act to the local legislature and government, state-run Xinhua reported.
Pan, also deputy to the Beijing Municipal People's Congress, started an online poll at 9:20 a.m. Tuesday, the results of which will be included in his report to the lawmaking body and the municipal government, he said.
Within three hours, more than 25,000 web users, or 99 percent of total respondents, welcomed his proposal on Sina Weibo, China's Twitter.
“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at China's top two oil firms, China National Petroleum Corp and China Petrochemical Corporation, saying the companies' outdated production technologies yield large quantities of substandard, high-polluting gas fuel that contains five times as much sulphur as gas products in the United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,” Xinhua reported.
"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."