For the past year, operators of the nation's truck fleets have been adapting to life with the new low-emission engines: They've recalibrated their systems; they've re-trained their maintenance staffs; they've even reconciled themselves to getting lower fuel mileage. And they've done all that with the full knowledge that even bigger adjustments lie ahead. As we report in our story on page 22, additional—and stiffer—emissions requirements take effect in 2007. Those stiffer requirements will almost certainly mean higher costs, which will be handed right on down the supply chain to the consumer.

Nobody welcomes higher prices, of course. Yet long term, it seems certain that the public will support tougher anti-pollution rules if the result will be cleaner air. The diesel that fuels the trucking industry—and indeed, the U.S. economy—remains a big part of the problem in that regard; it's a major source of pollutants. But even as engine makers and fleet operators work toward building and operating vehicles that reduce particulates and noxious gases, some out-of-the-mainstream ideas seem to hold at least a modicum of promise.

One of those is biodiesel, which is produced from such renewable resources as vegetable oil. Some small companies are producing the fuel from used oil collected from restaurants—an experiment that's given rise to vehicles with the aromatic properties of traveling French fries. Biodiesel can be used in existing diesel engines with little if any modification, its advocates say. And as a renewable energy source that doesn't make use of petroleum, it could help free the nation from its dependence on imported oil.

Biodiesel is not a panacea; the fuel is not without its problems, which means fleet managers won't be filling up their vehicles at the local McDonald's anytime soon. What's interesting from the perspective of fleet managers, distribution managers, and anyone concerned about clean air—in other words, just about all of us—is that such efforts are underway. The best hope for cleaner air in the near term will come from sustained effort by traditional fuel makers, engine OEMs and fleet managers to create cleaner-burning fuels and engines. Longer term, we'll have to come up with alternatives, and it's good to know that in laboratories, universities and small businesses around the nation, development of alternatives continues. Knowing we can continue to rely on ingenuity allows us to breathe a little easier.