But in our towns and cities, the biggest single contributor of the nitrogen oxides called nitrogen monoxide (NO) and nitrogen dioxide (NO2) – collectively referred to as ‘NOx’ – is transport fumes. Every car engine is, in effect, a mini lightning bolt, and our roads are filled with a never-ending storm. Nitrogen dioxide can cause significant health problems, and is therefore of the greatest concern, while nitrogen monoxide is less harmful but tends to react quickly in the air to form more NO2.
NOx
