A global air pollution survey by the World Health Organisation ranks Beijing near the bottom of a list of nearly 1,100 world cities.
Despite its brief success in combating smog during the 2008 Olympics, Beijing is now the 10th dirtiest capital city in the world, only cleaner than Ulan Bator, Gaborone, New Delhi, Islamabad, Riyadh, Dakar, Cairo, Dhaka and Kuwait City, according to WHO's first global survey.
Even more embarrassingly, the capital ranks 26th among the 30 mainland cities included in the study, with its 2009 reading of PM10s (tiny vehicle and dust particles of 10 micrometres or less) of 121 micrograms per cubic metre.
Ma Yongliang, of Tsinghua University, said the ranking underlined the gap between Beijing and international metropolises in industrialised nations in terms of pollution control. 'We've achieved great progress, but apparently there is much room for us to catch up,' he said.
Hong Kong, Macau and Taiwan are not included in the rankings, but pollution data of mainland cities are based on the China Statistical Yearbook 2010. According to the yearbook, Hong Kong's annual mean reading of respirable suspended particulates, which usually refers to PM10s, was 47 in 2009, which would rank the city 870th along with Manila and Turin, Italy.
Hainan's Haikou, which scores the best among mainland cities, ranks 814th on the pollution scale, with an annual average PM10 reading of 38mcg per cubic metre. Lhasa and Nanning come second and third, while Guangzhou ranks sixth with 70mcg.
The WHO recommends an upper limit of 20mcg for PM10s, which can cause serious respiratory problems, including lung cancer.