The shock news three months ago, that Volkswagen had used defeat devices to circumvent emissions tests in the United States, has brought back into the news a continuing problem of modern life - air pollution. The traces of pollutants coming out of tail pipes may seem to be little more than a nuisance, but it is actually a matter of life and death. One expert has estimated that this deception by Volkswagen has contributed to the deaths of 59 people in the States, their lives shortened by the damage nitrogen oxides have done to their bodies. A further 130 lives are at risk over the lifetime of the vehicles if nothing is done.

And air pollution comes from other sources as well as vehicles, such as fires and agriculture. Roland Pease looks into what can be done to clean up the air we breathe.

(Photo: Fumes blowing out from a car exhaust pipe)