"Up to 80% of the vehicle generated pollution is from approximately 20% of the vehicles on the roads". 

By using a screening method to identify gross polluting vehicles it has been shown previously that a dramatic reduction in urban air pollution can be achieved.  


An ideal method for screening road vehicles is to use a remote sensing instrument based upon a tunable diode laser absorption spectrometer.  The remote vehicle emissions monitor developed by TDL Sensors Ltd combines this state-of-the-art technology with a camera system for recording licence plates.  Through a rugged, highly-sensitive, and high-precision design, a practical field instrument for screening vehicles travelling into towns and cities has been achieved.  By remotely sensing the combustion efficiency of road vehicles, the "gross-polluting" vehicles can be quickly identified and action taken to have the offending vehicles re-tuned or repaired

How it works

Click here to view a Flash animation of the measurement process or click here to view a video.   

The laser beam is directed across the road of interest at exhaust height to a retroreflector which returns the beam back through the exhaust to the detector which is contained in the same enclosure as the laser. Background readings recorded before the car passes are subtracted from exhaust measurements.

Pollution measurements and vehicle identification are all performed within 0.5s after the vehicle has passed.

Field trials

Trials have taken place in collaboration with Leeds Highways and Kirklees council, UK on a main road heading into the city of Leeds. 

Plot 1: Number of vehicles and the contribution to CO emissions

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