On-road pollution monitoring for car exhausts

In the future drivers may only have to glance at their dashboards to see the pollution coming out of their vehicle's exhaust. A new laser measuring device capable of recording the levels of carbon dioxide, carbon monoxide and methane directly from the inside of an exhaust has been constructed by a team from The University of Manchester. By monitoring a vehicle's emissions while driving along, it is hoped the system will potentially help people reduce their emissions by adjusting their driving style. Monitoring gases inside the exhaust is faster and more sensitive than the normally used extractive measurement techniques which involve the gases being caught in a box and tested while the engine is idling.

The University of Manchester team employed a device known as a 'near-IR diode laser sensor' to measure the variation in gas concentration during changes in the operating conditions of a Rover engine, such as increasing and decreasing the throttle, adjusting the air to fuel ratio, and start-up. They have also taken the process outside the laboratory and measured exhaust emissions in passing vehicles. The near-IR device used two diode lasers operating at different frequencies; one detecting carbon monoxide and carbon dioxide and the other detecting methane.

This technology could also potentially be used in roadside congestion charging systems, with less polluting vehicles being charged less.