Xu Zongheng, the mayor of Shenzhen, one of China's largest cities, has asked residents to not buy any more cars, the Financial Times reported. Xu said car ownership is growing far faster than the city's ability to build roads and is causing heavy air pollution. "Although I have no legal power to do this, I am asking everyone to not buy cars," he told a public forum last week. The number of cars in Shenzhen, a city of 10 million, was likely to increase by around 200,000 this year while car exhaust could cause up to 70% of the city's air pollution. China is the second-biggest car market after the US. Last year, Chinese people bought 4.3 million new cars, and sales jumped 22% in the first half of 2007.