ABSTRACT
Some of the best known environmental impacts of road transport are emissions, mainly from exhaust gases, which affect local and regional air quality. Nitrogen oxides (NOx) are emitted from all internal combustion engines, and are hard to avoid as they result primarily from the nitrogen and oxygen in the air combining under the high temperatures and pressures of combustion. NOx is known to exacerbate respiratory illnesses, and is also a major component of acid rain.
