World

Heavy smog chokes northeastern China, as coal burning begins for winter heating

A woman wearing a face mask checks her mobile phone amid a heavy haze in Shenyang in northeastern China's Liaoning province Sunday, Nov. 8, 2015. Air quality reached extremely hazardous levels in the northeastern city of Shenyang on Sunday, as northern China began to burn coal to heat homes for winter. (Chinatopix via AP) CHINA OUT

A woman wearing a face mask checks her mobile phone amid a heavy haze in Shenyang in northeastern China's Liaoning province Sunday, Nov. 8, 2015. Air quality reached extremely hazardous levels in the northeastern city of Shenyang on Sunday, as northern China began to burn coal to heat homes for winter. (Chinatopix via AP) CHINA OUT  (The Associated Press)

Air quality has reached extremely hazardous levels in the northeastern Chinese city of Shenyang, as northern China begins to burn coal to heat homes for winter.

Real-time data released by the Shenyang Environmental Protection Agency showed the density of the poisonous tiny airborne matters known as PM2.5 was more than 1,000 micrograms per cubic meter on Sunday. Nearby cities also reported very high levels of the harmful particulates.

The World Health Organization considers the safe level of PM 2.5 to be 25 micrograms per cubic meter on a 24-hour average basis.

Local authorities say they have warned residents to stay indoors and demanded power plants to cut output.

Photos posted on social media show gray skies, and members of the public have been complaining of sore throats.