BEIJING, Jan. 22 (Xinhua) -- People living in south China have been grumbling aboutgales blowing smog in from the north, as hazardous air chokes more parts of the countrythis winter.
In 2013, China's smog belt stretched from the developed regions of the Yangtze andZhujiang river deltas and areas around Beijing and Tianjin, to other places where smog wasseldom seen. The southernmost province of Hainan and autonomous region of xizangrecorded smoggy days.
Chinese Academy of Sciences issued a report last month about climate change, saying thatbesides local pollutants, "smog migration" was another serious problem.
In Beijing, 30 percent to 40 percent of the PM 2.5, airborne particles smaller than 2.5microns in diameter, was caused by emissions, 20 percent to 30 percent from chemicalconversion in the atmosphere, and the rest from smog movement, according to the report.
Meanwhile, according to statistics published monthly by the Ministry of EnvironmentalProtection, Hebei Province, around Beijing, is home to up to seven of the country's top 10polluted cities.
Chen Changsheng, deputy director of the meteorological center of Jilin Province, said theidea of "smog migration" originates from "advection fog" that usually appears in winter andmoves with wind for a long period of time.
He explained that when advection fog emerges, local air particles like dust and secondaryinorganic aerosols -- sulfates and nitrates -- will mingle with the mist from other places,and generate smog, which means it is hard to correctly attribute the causes.
"The wind field in middle latitude makes smog movement possible from north China tosouth in winter," said Zhao Chuanfeng, a professor with the College of Global Change andEarth System Science of Beijing Normal University.
He said that big particles like dust can drop to land in one or two days, but tiny ones alwaysfloat in the air for much longer, moving with wind which forms smog migration.
Chen Nan, senior engineer with the monitoring center of Hubei Province, agreed with thepossibility of distant smog migration, but he said that intricate pollution discharge andweather conditions in winter sometimes prevent the spreading of smog.
Zhao also said that local influences are more obvious in generating smog, which needsconcrete analysis before any assertion that smog migrates from north to south.
However, no matter to what extent smog migration contributes to air pollution, theproblem has been awful enough for China to take action.
A popular Chinese joke "Christmas has to be canceled because Santa Claus got lost and fellin the snow" mocked the poor air quality on Christmas Eve, when smog readings of 16monitored cities, exceeded 300, about six times the safe level.
Serious air pollution plagues most major Chinese cities, where environmental protectionhas been sacrificed for the sake of economic development.
To tackle the worsening air quality, Zhao suggested cloud seeding for heavy rainfall towash 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, saidthat 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 fornatural 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 coaluse, shut down polluters, promote cleaner production and lower the density of inhalableparticulate matter. Putting the ambitious ideas in practice will cost an estimated 1.75trillion yuan (286.48 billion U.S. dollars).
