Chen Nan, senior engineer with the monitoring center of Hubei Province, agreed with the possibility of distant smog migration, but he said that intricate pollution discharge and weather conditions in winter sometimes prevent the spreading of smog.

Zhao also said that local influences are more obvious in generating smog, which needs concrete analysis before any assertion that smog migrates from north to south.

However, no matter to what extent smog migration contributes to air pollution, the problem has been awful enough for China to take action.

A popular Chinese joke "Christmas has to be canceled because Santa Claus got lost and fell in the snow" mocked the poor air quality on Christmas Eve, when smog readings of 16 monitored cities, exceeded 300, about six times the safe level.

Serious air pollution plagues most major Chinese cities, where environmental protection has been sacrificed for the sake of economic development.

To tackle the worsening air quality, Zhao suggested cloud seeding for heavy rainfall to wash out aerosol in the air, to prevent pollutants gathering into smog.

Lu Lunyan, China's climate and energy project manager of the World Wildlife Fund, said that the country needs a "revolution" in renewable energy sources to tackle air pollution.

She stressed that the country must adopt effective policies to decrease demands for natural resources and increase support for pollution solutions.

China has beefed up regulations and pledged financial resources to fight pollution.

A five-year action plan was unveiled by the central government in September to cut coal use, shut down polluters, promote cleaner production and lower the density of inhalable particulate matter. Putting the ambitious ideas in practice will cost an estimated 1.75 trillion yuan ($286.48 billion).