Alalam - China

PM 2.5 refers to damaging air particles so small they can pass through humans' lungs to affect other organs.
The acceptable PM 2.5 annual average set by the WHO is 20-25 micrograms per cubic metre.

Beijing's air quality likely improved 9.9 percent in 2016, the municipal government said in a document, and PM2.5 likely sat at an annual average of 73, better than the 2016 target of around 76.6.

But smog has engulfed Beijing and large swathes of the north and centre of the country for days at a time in recent weeks, disrupting flights, port operations and schools.

Environmental authorities on Saturday said bad air would strike provinces around Beijing in the coming days, the state news agency Xinhua reported.

Last week, Beijing said it would establish a police force to deal specifically with environmental offences as part of efforts to clean up its air and crack down on persistent polluters.