After spending more than 14 years in China, environmental expert Dimitri de Boer sometimes forgets about the smog.

Yet the sight of the US State Department's air quality index for Beijing, or the sound of his children coughing, soon brings him back to reality.

"Previously I liked to open the windows to get some fresh air. But then I realized the air I was letting in might not be so fresh after all," said De Boer, who is the team leader of the multimillion-euro EU-China Environmental Governance Program, a cooperation scheme between the European Commission and the Chinese Ministry of Environmental Protection.