Guangzhou's government has rolled out emergency measures for days when air pollution is high. They include taking nearly a third of government and half of private vehicles off the road and forcing factories to reduce emissions of pollutants. Yang Liu, director of the Guangzhou Environmental Protection Bureau, said yesterday that air pollution would now be formally categorised as an emergency. A 15-department task force would co-ordinate action centrally on days when the city was hit by intense smog. The announcement came two weeks after Beijing set out emergency measures to be taken when levels of PM2.5, the tiny airborne particles considered most harmful to health, are forecast to exceed 300 micrograms per cubic metre for three consecutive days. Air pollution is now a top public concern in several mainland cities, many of them in the north, where energy generation relies heavily upon coal-burning plants. In Guangzhou, the contingency measures will be activated under an orange alert. That will come into force when the air quality index is forecast to reach between 201 and 300 for 48 hours at five of 10 monitoring stations. Authorities will then take 20 per cent of the city's 13,000 government vehicles off the road. Under a red alert, triggered when the index exceeds 300, 30 per cent of government vehicles will be kept off the roads. Private vehicles will be usable only on alternate days based on whether their licence plate ends with an even or an odd number. Guangzhou's air quality index has not passed 300 in the past three years. It reached the level that would now trigger an orange alert on two days in 2011 and three days last year. Unlike Beijing, Guangzhou did not list school class suspension as mandatory on alert days. "Whether to suspend class is a preventive health guideline and we are relying on our education authorities to map out implementation details," Yang said. "All of our measures, including ways of informing citizens, monitoring and implementation, will require going through drills so we can effectively notify people and minimise inconvenience." Under a red alert, factories will be required to cut emissions by 30 per cent. Fireworks and outdoor barbecuing will also be banned, and there will be stronger monitoring of restaurant kitchens and petrol stations. Employers will be encouraged to allow staff to work flexible hours. According to Yang, the measures are in line with what the Beijing, Shanghai and Foshan city governments have unveiled, but Guangzhou has in addition specifically targeted ozone in its emission limits, which has proved a consistent concern in the city.