Lab shows vehicle emissions tests are flawed
6 October 2015 Last updated at 00:03 BST
An experiment at The University of Manchester - running a diesel engine inside a lab - is demonstrating just how far manufacturers' emissions tests fall short.
By piping the engine's emissions into an atmospheric chamber, the team can recreate what happens when engine pollutants enter our own atmosphere.
Dr Rami Alfarra, from the University of Manchester, explains how his team's research has shown that engines are much more polluting when we are really driving than standard car-makers' tests reveal.
The research is a collaboration with atmospheric chemistry researchers at the University of York.