Vapor lock: environmental regulators target diesel emissions.

Diesel emissions, the fumes voted least likely to become a Glade air freshener, have come to the attention of environmental regulators. Guess what? The regulators don't like them. In fact, the regulators dislike them so much that they're working toward banning them altogether, though in greenspeak that's called "fostering the adoption of alternate fuels."

Touting recent findings that diesel emissions are YAC (Yet Another Carcinogen), several groups in California - a state that has consistently set national environmental trends - have stepped up their efforts to eliminate the use of diesel fuels. In the northern part of the state, the California Air Resources Board, the agency responsible for regulating the state's air quality, is pondering whether to declare diesel emissions a "toxic threat." In Southern California, state Attorney General Dan Lungren (who just happens to be the Republican nominee in this fall's race for governor) has joined with four environmental groups to sue area supermarkets for endangering people's health by having all that health-preserving food delivered via health-infringing diesel trucks.

These efforts in California may well serve as the prelude to a nationwide campaign: Diesel emissions are targeted by the U.S. Environmental Protection Agency, which is implementing new regulations against particulate emissions. (See "Polluted Science," August/September 1997.) And the Natural Resources Defense Council has hosted photo-ops in California and New York City, highlighting the presumed health risks of exposure to diesel fumes.

Granted, diesel emissions are noxious. Granted, too, that the small particles in the fumes are lung irritants. And granted, they are probably carcinogenic. The question is, other than scaring people half to death, what should we do about the fumes? Few pollutants are "pure risks" - that is, solely toxic and life destroying. Most are somehow bound up in the production of goods and services that provide real benefits to people. Although utopian environmentalists hate to talk about trade-offs and cost-benefit analyses, the proper regulatory framework is to consider risk in relative terms: After counting up the good, the bad, and the ugly effects of a given substance, will eliminating it cause more harm than good?

So the diesel health risk needs to be put in perspective. Though hotly - and unsurprisingly - disputed by the trucking industry, the most recent credible estimate of diesel lethality is a lifetime probability of 450 lung cancers for every 1 million people casually exposed (those persons who aren't, say, truck drivers, diesel mechanics, or otherwise frequently exposed to diesel emissions as part of their jobs). Taking that at face value, simple math implies that of roughly 250 million Americans alive today, 112,500 people will eventually die from a disease that is somehow related to exposure to diesel emissions. That's not a small number. But assuming that the deaths are distributed evenly throughout an average lifespan of 72 years, that's 1,562 deaths per year. Not a small number either, but not even a contender in comparison with other avoidable causes of death.

In 1995 alone, according to the National Center for Health Statistics, over 700,000 people died from heart disease; 158,000 died from strokes; 90,000 died from accidents; 84,000 from pneumonia and flu; 43,000 from AIDS; 31,000 from suicide; and 25,000 from chronic liver disease and cirrhosis. In 1996, transportation accidents alone claimed over 44,000 lives, while prostate cancer claimed 41,000.

So the health effects of exposure to diesel fumes, while significant, don't stack up against other, more significant risks. More important perhaps, while diesel emissions might be noxious and unhealthy, the use of diesel fuel brings with it considerable benefits. Through its role in bringing lower-cost goods and services to market, it has considerable health-affirming effects that must be factored into any analysis. We know, after all, that the biggest health-nurturing features of our economic system are dependent on lower costs: Access to a broad range of healthful foods, sophisticated medical care, cleanup of truly toxic environmental contaminants, and investment in high-return improvements like automobile safety are linked to maintaining a robust economy.

Hence, before banning diesel out of hand, we need to assess what might replace it. Diesel engines are the primary choice in trucking, rail, and inland marine transport for very good reasons: They are highly efficient, and the fuel is less expensive than other types, especially in terms of efficient movement of mass. Diesel trucks in particular move a lot of mass and bring a lot of services out to consumers. Trucks carry 90 percent of all goods by value and 67 percent by weight. Raw materials are moved an average of seven times by truck before they're offered for sale.

Diesel engines are also easy to maintain and durable, which means they have a long life. The diesel engines in today's newer trucks were purchased with the expectation of amortizing their costs over a 35-to-40-year life. Given all of these advantages, and the pervasiveness of diesel-fueled trucks, any attempt to make rapid or large-scale changes in the use of diesel fuel in trucking will have serious ramifications for the cost of goods and services.

Still, switching fuels is the favored solution in the environmental advocacy community, which portrays substitution as a feasible option. Such optimism is not borne out by the facts. Gasoline, the most readily available alternative to diesel fuel, presents exactly the same emissions problems for which diesel is damned. In addition, diesel engines are almost twice as efficient as gasoline engines, and diesel fuel is less likely to catch fire. Gasoline engines also have shorter lifespans and higher maintenance costs than their diesel counterparts. Finally, diesel engines actually put out less of the ballyhooed greenhouse gases - hydrocarbons and carbon dioxide - than gasoline engines.

Compressed natural gas, the second most readily available alternative fuel that is suitable for both new engines and retrofitted older engines, is several times less efficient than diesel and several times more expensive, and it involves higher engine maintenance costs. It also puts out higher levels of hydrocarbons and carbon dioxide than diesel engines. Additionally, the infrastructure is nowhere near ready to dispense the mass of fuel needed as a replacement for the entire fleet of diesel trucks currently in use.

The other major alternative is hydrogen-powered fuel cells, the darling technology of industrial policy technocrats. All estimates agree, however, that, despite the production of a few very costly and marginally performing demonstration buses, we're decades away from their being viable replacements for any kind of internal combustion engine.

Beyond the efficacy of switching fuels, there's a regional question that needs to be considered: The federal government has already shown that it's unwilling to elevate diesel fuel to public enemy status at the national level. Will California impose a standard only on trucks that travel through California? What will that do to the cost of California goods and services, compared to those in other states? How will that affect California's recovering but periodically fragile economy?

The bottom line on eliminating diesel fuel, then, must factor in answers to questions such as: Will increasing the cost of foods make us safer? Will forcing families to spend more on clothing, and by default, less on medical care, make them safer? What about state competitiveness? Is presenting the risk of diesel fuels to the public in an isolated and distorted manner truly in the public interest? Is it wise to set a process in motion that will cause a massive change to our shipping infrastructure, with equally massive changes to our health-nurturing economy, without considering the overall consequences?

And any discussion of the topic needs to acknowledge an important and ongoing development: There are ways to clean up diesel emissions, and those ways are already being adopted in response to public sentiment and existing air-quality regulations aimed at the nuisance factor for diesel trucks and buses. Modern diesel engines put out 95 percent less particulate pollution and 70 percent less nitrogen oxide emissions than did their 1970s forerunners. There are already technologies in the pipeline that will produce cleaner diesel engines; these include using reformulated fuels, new catalytic converters, and more advanced fuel-injection systems. The diesel problem is already going away.

Rather than trying to scare, sue, and regulate our society into a stampede toward untested and utopian technologies, regulators, public health advocates, and technocrats would serve the public far better by taking more care with our risk reduction investments, by targeting the biggest risks first, by addressing only those risks that can reap the "benefits of scale" that broad-brush governmental risk reduction relies upon, and by otherwise allowing the basic process of industrialization to work. After all, that process results in more-efficient fuel use and fewer emissions over time.

Indeed, though the credit won't belong to environmental regulators, it's a safe bet they'll claim the eventual emission reductions as their own. Their constituencies will be happy, and the forces of the market will ensure that the amelioration of yet another relatively low-level risk is done incrementally, efficiently, and at a rate that the economy can absorb.

Kenneth Green ([e-mail]) is chief scientist at the Reason Public Policy Institute.