increasing economic growth has raised the levels of atmospheric nitrogen dioxide (no₂) over the industrialised northeast China to the highest in the world, according to a new study of satellite images. no ₂ levels from the ground to an altitude of 10 kilometres, are about 50 per cent higher than earlier bottom-up estimates, and are continuing to increase, it says.

Previous calculations used figures for the amount of fossil fuels burnt to gauge the amount of no₂ released. But researchers at the University of Bremen, the Max-Planck Institute of Meteorology in Hamburg and France's Centre National de la Recherche Scientifique used satellite images from the Global Ozone Monitoring Experiment (gome) on ers-2, and Envisat's Scanning Imaging Absorbing Spectrometer for Atmospheric Chartography (sciamachy).

gome generated the first satellite data on no₂ levels, which it mapped from 1996 to 2002 (see image: Satellite estimates). These were then matched with the no ₂ column readings from sciamachy from December 2003 to November 2004. sciamachy has a higher spatial resolution, and was used to confirm the original gome findings.

The only feasible reason for these levels of no₂, say the researchers, is the rapid economic growth that has occurred in China over the past decades.

The major mechanism for the formation of no₂ is the oxidation of nitric oxide, which is produced by most combustion processes. The increase in industry, and number of vehicles on the roads (see [2]