Dust kills. That's the oversimplified but powerful implication of a thorough study of the impact of microscopic airborne particles on human lungs. The conclusion is important for truck operators because a major source of these particles is truck emissions, particularly sulfur. The news makes it more likely that EPA will follow through on a variety of rules to remove sulfur from fuels.

One of those rules would lower the allowable sulfur content in on-highway diesel fuel from the current 500 ppm to 15 ppm. Refiners and petroleum marketers are battling the EPA in federal court to stop the rule on procedural grounds. But now, even if they win in court, Congress may decide to enact some version of the rule for the sake of public health. The EPA may also adopt another rule that would force operators of trains and off-highway vehicles and equipment to use low-sulfur diesel instead of the high-sulfur fuel that trucks had to stop using in 1993.

Meanwhile, gasoline is also facing changes and challenges. In a separate rulemaking, EPA has mandated that sulfur be removed from gasoline. Congress and the Administration may adopt further incentives for blending ethanol into gasoline. Already, gasohol consumption is rising faster than straight gasoline. And several states may ban a popular ingredient used to make oxygenated gasoline, MTBE, further pumping up ethanol use.

At the same time, automakers are working on a couple of alternatives to pure gasoline engines. Soon more vehicle types will operate on engines that automatically switch between gasoline and internally generated electric power. In a few years, hydrogen may provide the power, although it is not clear if gasoline or some other form of energy will be the source of the hydrogen.

Why does this matter to truck operators? First, the new fuel and engine types may be suitable for light delivery and vocational trucks, not just cars. Tax incentives for alternative fuels, fueling facilities and the vehicles that use them may make these vehicles more attractive to buy and operate than the traditional choices. Congress extended existing tax incentives for electric and alternative-fuel vehicles and facilities in the “stimulus” bill it passed in March. Additional tax breaks are likely to be included in an energy bill, if it ever reaches the President's desk and becomes law.

Second, as the economics of gasoline change, so will the price of diesel. If refiners find less of a market for gasoline, they will produce more diesel from each barrel of crude oil. That should bring down the cost of diesel fuel. Offsetting this trend, however, higher capital costs to retool refiners and higher operating costs to produce all types of low-sulfur fuels may make diesel more expensive.

Third, alternative fuels are generally taxed more lightly than gasoline or diesel. That means federal and state highway funds will either have less money coming in or may make up the shortfall by taxing trucks and traditional fuels more heavily.

The bottom line: Anyone buying a truck in the near future has a lot to consider. Just as the 1993 switch to 500-ppm diesel fuel was accompanied by price spikes, localized fuel shortages, and reports of engine failure, diesel buyers may face similar headaches if 15-ppm fuel is mandated. Worse, local, state or federal agencies might impose impossible operating restrictions in the name of keeping diesel trucks from spewing “killer dust.” Even if none of these issues comes to the fore in the next three years, the resale value of a truck bought today could be severely impaired. Yet alternatives to traditional diesel fuel and diesel-powered trucks are still untested or problematical.