That's because the Beijing authorities simply ban burning coal and limit the gas supplement in nearby areas. check this out http://www.xinhuanet.com/local/2018

That's because the Beijing authorities simply ban burning coal and limit the gas supplement in nearby areas. check this out http://www.xinhuanet.com/local/2018-02/05/c_1122367331.htm http://www.xinhuanet.com/local/2018-02/05/c_1122367331.htm