A view of Paris from a hot air balloon: putting pollution on the climate agenda

Beijing may hit headlines, but European cities such as Paris also regularly exceed safe limits for pollutants such as NO2, with impacts on health and climate change. John Vidal takes to the skies to get a clearer picture

The air quality is officially "good", 400ft above Paris in a balloon at rush hour. From that height you can see the ring road and many of the city's 37 bridges blocked with traffic, the commuting trains coming in, and - on the first cold day of winter - water vapour rising from several power stations as thousands of central heating systems fire up .

A yellowish haze has formed on the horizon as air pressure builds, but the pollution from Paris's transport, construction sites and power stations is minimal compared to that of Beijing or New Delhi at this time of year.