Beijing: The equivalent of the population of Bristol dies each year in China because of air pollution, according to the country’s former health minister.

Chen Zhu, who is also a professor of medicine and a leading molecular biologist, is the most senior government official to put a human cost on the smog that regularly clouds Chinese skies. Until recently, any mention of deaths relating to pollution was strictly censored.

Chen’s claim came in a commentary in December’s issue of The Lancet, the respected medical journal, co-written with Wang Jinnan, Ma Guoxia and Zhang Yanshen from China’s ministry of environmental protection.

“Studies by the World Bank, WHO, and the Chinese Academy for Environmental Planning on the effect of air pollution on health concluded that between 350,000 and 500,000 people die prematurely each year as a result of outdoor air pollution in China,” Chen and his fellow authors wrote.

He added that air pollution had become “the fourth biggest threat to the health of Chinese people” — behind heart disease, dietary risk and smoking — and that lung cancer was “now the leading cause of death from malignant tumours in the country”.

Chen, who was health minister until last year and remains a senior official on the standing committee of China’s legislature, said the country “now produces the largest number of major pollutants in the world” and accounted for half the world’s coal consumption.

The estimate that the authors quoted is lower than the 2010 Global Burden of Disease Study, also published in The Lancet, which estimated that airborne particles smaller than 2.5 microns in diameter (PM2.5) caused 1.2 million premature deaths in China in 2010 alone.

Chen said the Chinese government had now enacted “tough measures” in order to fight the smog. He said research showed that 200,000 people would be prevented from dying prematurely each year if cities reached targets set out in newly revised air quality standards.

Between 2002 and 2011 the incidence of lung cancer in Beijing near doubled. Nationwide, deaths from lung cancer have risen 465 per cent in the past three decades.

Smoking remains the leading cause, but the number of smokers is falling while lung cancer rates are rising.

Chen’s commentary is particularly notable because in 2007 Chinese censors removed a claim that air pollution caused 350,000 to 400,000 premature deaths from a joint report between the World Bank and the Chinese government.