Air pollution is a severe problem – one that we ignore at the risk of our health and our economy. Smog hangs heavy over Beijing, Shanghai and Hong Kong, where children grow up with asthma and other respiratory illnesses.

Of particular concern is PM2.5 (particles with an aerodynamic diameter less than 2.5 μm) air pollution. In Beijing, Shanghai, Guangzhou and Xi’an, PM2.5 concentration levels in all four cities exceed World Heath Organisation (WHO) air quality guidelines. This means higher health risks to the cardiovascular system, cerebrovascular system and an increase in the probability of cancer and premature death.