An eight-year-old girl has reportedly been diagnosed as China's youngest victim of lung cancer, reigniting debate over the devastating human toll of the country's pollution crisis.
The girl, who was not named, lived near a busy road in the eastern province of Jiangsu and doctors blamed exposure to air pollution for her condition, state media reported.
Jie Fengdong, a doctor at Nanjing's Jiangsu Cancer Hospital, was quoted by the state-run China News Service as saying the likely cause was exposure to tiny airborne particles from vehicle emissions.
Kan Haidong, a professor from the School of Public Health at Shanghai's Fudan University, said it was "very, very rare" for such a young child to be diagnosed with lung cancer and urged caution in making a direct link to pollution.
Children were more vulnerable to air pollution than adults, but 40 percent of lung cancer cases were still caused by smoking, Dr Kan added.
Still, the revelation sparked renewed discussion about how to clear China's smog-choked skies and came as Xie Zhenhua, the country's top climate change negotiator, admitted that air pollution had "severely affected the mental and physical health of the Chinese people".
Speaking in Beijing, Mr Xie blamed the crisis on China's "obsolete development model" and excessive use of fossil fuels, adding: "We face daunting difficulties and challenges ahead."
The coming weeks are likely to see thick smog envelope cities across China as winter approaches and coal-fuelled power stations start to come online.
Already the problems are being felt. In late October, toxic smog brought Harbin, a city of more than 11 million people in northeastern China, to a virtual standstill – closing schools and roads and grounding aircraft.
In June, China's official news agency Xinhua said six people were now being diagnosed with cancer every minute, with around two million deaths each year.
"In 2020, there will be 4 million new cases of cancer in China every year," Chen Wanqing, the vice director of China's National Cancer Prevention and Control Research Office, told the agency.
On Tuesday, Jiangsu province's Modern Express newspaper reported that, "the exact cause [of the girl's cancer] has not been determined."
But Li Tian, a doctor from the Nanjing Chest Hospital, said cancer rates were rising and that patients were getting younger, with the highest growth group being those aged between 20 and 40.
Wang Zhaoxia, another Nanjing doctor whose hospital treated over 600 lung cancer patients in 2012, said smoking and passive smoking remained the main culprits but said air pollution was also a factor.
Chinese smog was now becoming a "threat to national security" as well as public health, Hong Kong's South China Morning Post reported on Tuesday.
Two special research teams – one military, one civilian – had been set up to find a solution, it added.