Regions shrouded in heavy smog over the past week are lifting their hazardous weather alerts as a new cold front drives the pollution away.

Cities in northern China have seen clear blue skies again on Sunday. The central meteorological bureau has now lifted its nationwide double alert for haze and fog although Shanghai remained hazy on Monday morning, although the city’s weather center said it was more a result of moist fog rather than the hazardous fine particles in smog.

Smog in other regions is also expected to disperse as cold air accompanied by wind arrives late Monday or Tuesday. Since the start of December, large parts of China have seen smoggy weather which has led to closures of highways and school as well as flight delays.

13 provinces have reported record high numbers of hazy days this year.