UK's first pollution cameras trialled in Birmingham and London
15 February 2016 Last updated at 17:13 GMT
The UK's first pollution cameras have gone up on roads in Birmingham and London to measure emissions from cars.
It's part of a trial by the Universities of Birmingham, Leeds and King's College London, funded by the Department for Transport.
The US-manufactured devices shine a laser beam through exhaust fumes and use reflected light to measure levels of toxins.
In America, the cameras are used to identify and reward the cleanest car drivers from their annual emissions test.