Microscopic particulate matter, a serious contributor to air pollution from vehicles has until now, been largely ignored by the government and also therefore by many local authorities
However, better late than never, the government seems at last to be taking this dangerous threat to our health more seriously. The source of much of these particulates (PM 2.5 to 10) is diesel combustion but increasingly there is now an awareness of how the wear and tear on vehicle breaks and tyres and on road surfaces is contributing to the problem.
You can read about the government's attempts to gather evidence on the sources and levels of particulate concentrations in the air we breathe here