Issue: A handful of states have begun issuing citations to trucks emitting excessive amounts of smoke, and more regulations are on the way. Smoky diesel exhaus t is giving the industry a bad name - it's time to take action.

Thanks to major advances in engine technology and the use of cleaner fuel, emissions from new diesel trucks are dramatically reduced. In fact, diesel engines are so much cleaner today that eight new trucks emit as much pollution as just one purchased in 1987.

Despite this progress, however, communities and citizens continue to be concerned about black smoke from diesel bus and truck engines. Even though new engines have virtually no visible emissions during normal operations, smoke from older engines is a significant and growing concern.

In addition to improving the environment, minimizing smoke emissions enhances the industry's image. The safest drivers in the world will leave a negative impression if they are driving trucks that are belching out black smoke. And for fleets, public perception is an important part of business.

Fleet managers recognize that a smoking truck is a truck that is not operating at peak efficiency. Smoke emissions mean higher operating costs, lower fuel economy, higher maintenance costs, and shorter engine life - all of which lead to more costly fleet operations.

Owners, operators, drivers, and mechanics each have an important role in assuring that engines minimize smoke emissions. Dark black smoke indicates incomplete combustion, while droplets of unburned liquid fuel and water vapor, typically occurring at startup or while a truck is idling, result in white smoke. Blue smoke usually means that unburned engine oil is mixed in the exhaust, typically the result of worn piston rings, cylinder liners, valve guides, or other components. Proper maintenance at manufacturer-recommended intervals should easily detect, repair, and prevent these problems, while assuring that your truck is in the best and most profitable operating condition.

Excessive smoke emissions can also be caused by poor driving techniques. To minimize smoke emissions, train your drivers to accelerate moderately, downshift to a lower gear instead of "lugging" the engine, and avoid full throttle on steep inclines, especially under loaded conditions.

Common misconceptions about engine power sometimes lead drivers or maintenance personnel to perform costly and dangerous engine tampering. Tweaking fuel flow, changing timing, and disabling air/fuel controls can all rob your engine of durability - not to mention increase smoke emissions. Tampering with or disabling any component of an emissions control system is against the law and can result in fines of up to $25,000 per day. Think about the impact that could have on your bottom line the next time a driver asks for more power.

In addition to anti-tampering laws, a number of states are enforcing smoke opacity standards for heavy-duty diesel vehicles. Arizona, California, Colorado, Kentucky, and New Jersey require annual inspections for vehicles domiciled and registered in their states, while Washington has a biennial requirement for non-government vehicles. In addition, annual inspections will be mandated beginning this June in the New York City area.

California, Connecticut, Nevada, New Jersey, and Vermont are all conducting roadside diesel-emissions enforcement programs for vehicles traveling in their states. In New York, state law requires that the roadside program be under way by June 1, 1999; New Hampshire's pilot program will begin this winter; and Maine's pilot program will shift to the enforcement phase in September 1999. These programs have the advantage of focusing on vehicles that are gross smoke emitters, while imposing no obligations on fleets that operate well-maintained vehicles.

Roadside inspections, as well as some annual inspections, rely on a "snap-acceleration" test, which is conducted by measuring the exhaust smoke while the throttle of a stopped truck is rapidly depressed until the engine reaches maximum governed speed. Exceeding state-allowed smoke levels can result in fines ranging from $500 to $1,500, althoughmany states waive or reduce the fine if proof of repair can be demonstrated.

Last year the American Trucking Assns. (ATA) and the Engine Manufacturers Assn. (EMA) launched a campaign called "On the Road to Clean Air" to educate trucking companies about their role in protecting the air we breathe. It's time for us to define ourselves as a proactive, environmentally responsible industry that takes initiatives beyond basic compliance. Remember that this is an economic as well as an environmental issue because a well-maintained truck with a clean exhaust pays for you and the environment.