Emissions Tests for Trucks?

August 03, 1993

When you spot a heavy-duty rig barreling down the highway while belching black plumes of exhaust into the air, it raises serious questions about the fairness of Maryland's emissions-inspection program. Cars must undergo anti-pollution tests every other year, but there is no testing at all of heavy diesel trucks.

Yes, that is unfair. Diesels may not contribute heavily to the smog problem in the Baltimore and Washington regions, but diesel smoke is a recognized carcinogen, and the soot emitted from heavy-duty diesels apparently plays a role in lung, respiratory and heart conditions. Maryland is also under the gun from the federal government to reduce its smog by 2005, and cutting down emissions from diesel rigs would still help.

Eight weeks ago, the state began a pilot program of roadside, voluntary testing of big trucks. So far, 40 percent of the rigs have flunked the emissions tests, a failure rate that is far too high. The question now is how to bring that figure down.

A full-scale, mandatory emissions-testing program for heavy trucks would be expensive to set up and maintain -- the reason the state Senate killed such a bill two years ago. Spot testing on major highways might prove financially feasible, though.

State transportation officials also might consider talking with truckers at weigh-in stations to drum into their heads the importance of keeping engines properly and regularly tuned and of adopting driving practices that encourage fuel-efficiency and decrease pollution. Most diesel truckers understand the importance of cutting smoke emissions while improving their gas mileage, but offenders are giving trucking a bad image.

One encouraging development is that tougher federal pollution standards for new diesel engines take effect this fall. So there should be a gradual elimination of much of the problem over time as trucks are replaced. But some form of emissions testing for heavy diesels still seems appropriate. The trick for state officials and legislators is to come up with a solution that doesn't cost taxpayers too much yet hammers home the message to wayward truckers that spewing black clouds of smoke isn't good for anyone's health.

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