Engineering Innovation Podcast and Radio Series

Dirty Emissions? He'll Catch You!

PostedNovember 9, 2003

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Most cars will pass, so why not just bring polluting cars in for emissions testing?  How?  Colorado chemist and engineer, Donald Stedman tests cars in a split second as they pass by a highway entrance ramp.  He's set up a knee-high light source on one side of the road, a detector on the other.  As the various beams pass through your car's exhaust plume, each pollutant there absorbs one of them.  So the light making it to the detector tells how much pollution your car is spewing, as your license plate is photographed.  Only drivers with dirty exhaust are asked to visit the testing station.  Stedman says that if you drive a lot you'll likely use main roads and will get measured—maybe many times—and if you don't drive much, who cares?  With the National Academy of Engineering, Randy Atkins, WTOP Radio.