A contingency plan to deal with hazardous air pollution was released by the Shanghai municipal government yesterday. Though it came nearly six months after a similar plan in Beijing, Shanghai's plan features measures that are considerably tougher than those in Beijing. According to the plan, published on the website of the Shanghai Environmental Protection Bureau, the government intends to issue a public alert and take its most comprehensive emergency action when the air quality index exceeds 300. By comparison, the index must hit 500, the highest level of the pollution index, before Beijing takes its most stringent steps to reduce pollutants in the air. During such an emergency, the Shanghai government plans to boost output of natural gas power plants, in order to reduce emissions from coal-fired power plants. In addition, more electricity would be bought from other provinces, and authorities would require all coal-fired plants in the city to use their cleanest coal. When the pollution index hits 300 in Beijing, the government checks to ensure that all coal-fired power plants are using mandatory pollution-reduction devices. But it is not until the index hits 500 that some building activities, such as excavations and demolitions, are suspended completely. In Shanghai, nearly all building projects will be forced to temporarily cease operations when the index hits 300. Shanghai said it would also halt production in industries related to chemicals, steel, oil refinery and cement manufacturing on bad air days. Both cities have also promised to reduce the number of government cars on the road by 30 per cent, but Shanghai went a step further by banning all heavy trucks carrying dust-causing materials when the pollution index hits 300 - a step Beijing does not take even when the index reaches 500.