beijing northern chinese cities fail improve air quality much last month hit smog-prone region overall result drive pollution government say warn provincial officials comply stringent step clear sky cities improve air quality much even experience volatility way drag regional air quality level ministry environmental protection mep spokesperson liu youbin say regular brief thursday identify underperform cities comment come amid concern country ability reduce pollution winter battle avoid repeat near-record level choke smog envelop key northern areas start year jest war local officials enforce measure campaign effectively could improve air quality time hold accountable liu add data early month show four 28 northern chinese cities meet air quality target october air quality 338 chinese cities worsen october level hazardous breathable particles know pm 2.5 5.6 percent year average 38 micrograms per cubic meter beijing huge pressure meet politically crucial air quality target clear sky toxic smog blanket north country home turn heat power coal liu say overall air quality northern cities improve compare september average pm 2.5 level region drop 15.8 percent october month say show measure work long persistent diligently enforce exist measure regional air quality definitely improve say six-month campaign 28 northern chinese cities order thin traffic cut industrial output thousands pollution source include steel mill coal-fired boilers cement ceramic plant mine build sit shut measure part beijing years-long time war smog already roil commodities market fuel worry tough inspections hurt already slow economy joke china government warn northern cities get serious war smog