With its skies regularly shrouded by a filthy film of gray smog , bringing chaos to the transportation network and forcing millions to seek refuge behind surgical masks , Beijing has been forced to take more extreme action . Officials in China 's capital this week announced a raft of emergency measures in a bid to tackle the problem , including mandatory factory closures and bans on cars entering the city on days when pollution levels are particularly high . While Beijing is not alone when it comes to smoke-filled skies , this city of more than 20 million people has come to symbolize the environmental cost of China 's break-neck economic growth . Red alert . The city 's Heavy Air Pollution Contingency Plan stipulates that when there is `` serious pollution for three consecutive days , '' a warning system comprising of blue , yellow , orange and red -- the most serious -- alerts will be activated . Kindergartens , primary and middle schools will then have to stop classes , while 80 % of government-owned cars must be taken off the roads . Private cars will only be allowed to enter the city on alternate days according to ballot system of the numbers on their registration plates . All freight vehicles and those transporting material for construction sites will be barred from the roads when the red alert is issued , while more watering carts and sprinkler trucks will take to the roads , the state-run China Daily reported . Factories in the city emitting pollutants will be required to cut their emissions or shut down completely when the orange warning signal is hoisted , while construction sites must halt excavation and demolition operations . Other measures include a ban on barbeques and fireworks on heavily polluted days . Harmful to health . According to the plan , these emergency measures will come into play when the air quality index for fine particulate matter , PM2.5 -- airborne particles considered most harmful to health -- exceeds 300 micrograms per cubic meter for three days running . The `` safe '' limit is 25 micrograms , the World Health Organization says . While the announcement has been broadly welcomed as a step in the right direction , doubt remains about its long-term effectiveness . `` The new emergency measures show the government 's determination to tackle the air pollution in Beijing , especially those regulations that limit car use and close schools and kindergartens on heavily polluted days . It shows that the authority has really paid attention to those vulnerable groups , '' Huang Wei , a spokesman for Greenpeace East Asia , told CNN . `` But what is problematic is that those emergency measures are only targeted to those polluted days . It is rather a remedial measure than a preventative measure , and just to repair wo n't help the issue in the long run . `` The air pollution in Beijing is mostly transmitted from other cities , and what Beijing can do is very limited . What the authority should do is to build a linkage mechanism , combining preventative measures with emergency control . For instance , factories in surrounding areas like Inner Mongolia , and Shandong Province could close their factories in advance before the potential transmission of serious pollutants . It should be collaborative work between cities , and only Beijing is not enough . '' Popular opinion . This view was backed by many ordinary Chinese on Weibo , China 's popular micro-blogging service . `` They should have some long-term thinking instead of always waiting till the crisis happens , '' posted one user with the handle Shijinmilu . Another , called Qinghualiuqingyu , asked : `` How about those people who ca n't afford an expensive house in the city and have to take cars to work every day ? '' `` Cars are not the main polluters , surrounding factories are . Sometimes the pollution level still goes up crazily even it 's around 2 or 3 a.m . The policy itself is good , but it 's more important how they implement it , '' said TangyuanAllesGute . Positive action . Last month , the central government in China announced plans to start listing its top ten most air-polluted cities every month in the hope that national humiliation will push positive environmental action . `` We must put air quality control as an ecological red line for economic management and social development , '' China 's Vice Premier Zhang Gao Li said in a statement as he announced the new policy at the 18th Air Pollution Control Conference in Beijing . Chinese officials did not say when the first list would be announced , but the northern megacities of Beijing and Tianjin , as well as the surrounding provinces of Hebei , Shanxi , Inner Mongolia and Shandong have signed onto an official plan to speed up air pollution control measures . Meanwhile , life was returning to some semblance of normality in northeastern China Wednesday as days of smog-filled skies brought one city to a standstill . Thick smog closed Harbin 's international airport , affecting hundreds of flights , and closed schools and businesses as visibility in some areas was reduced to less than 20 meters ( 65 feet ) . Some buildings could barely be seen from the opposite side of the street , while drivers brave enough to take to the roads were forced to flash their hazard warning lights . The unusually severe pollution levels were blamed on the city 's coal-fired heating system , as well as farmers burning straw as temperatures in the region begin to drop .
Beijing authorities to close factories , reduce vehicle traffic to reduce pollution . These measures come into effect after ` ` three consecutive days '' of smog . China 's capital has raised the environmental cost of economic growth . Environmentalists say growth must involve more than one city .