Good news: one form of air pollution may be falling in Europe

motorway busy with cars — Car trouble: air quality is still a health issue despite drop in nitrogen pollution

By Chris Baraniuk

The fumes belched out by road vehicles are deadly – but levels of one harmful component, nitrogen dioxide, may already have peaked in Europe.

“It’s not air quality solved or anything, but it is positive,” says lead author Stuart Grange at the University of York, UK.

Nitrogen dioxide (NO₂) is a polluting chemical released by petrol and diesel vehicles. Each molecule contains one nitrogen atom and two oxygen atoms. NO₂ is blamed for tens of thousands of deaths in Europe each year. A second variant, nitric oxide (NO), contains only one oxygen atom per molecule – but over time it tends to change into NO₂. Collectively, the two are known as NO_X.

Grange and his colleagues