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.
Mr 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.