Auto-Economica (and Air Pollution)

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Editor's note: Two months ago, here in New York City, a judge ordered the mayor's office to study possible health effects of garbage truck diesel emissions. So we at ACSH read the following letter from a reader with some sympathy.

Dr. Whelan:

When I read a recent article in the New York Times, I thought of your May 23, 2000, ACSH editorial "Can Too Much Safety Be Hazardous? A Critical Look at the 'Precautionary Principle'." I hope you will comment on the following situation.

As reported in the Times (with little concern for the outcome), certain unscientific political lobbies have prevailed on the EPA to use its considerable discretionary authority to curb certain vehicle emissions regardless of the consequences to the nation's transportation system. It is not clear which result will accomplish the EPA's objectives of reducing auto exhaust: the expensive new engine emission control technologies that are subject to EPA certification for on-highway use, or just the expense of obtaining new engines that will by itself eventually lessen the numbers of emitters legal to operate on the highway.

Notwithstanding the seeming endorsement of the New York Times, the public health benefits obtainable from this regulatory initiative seem questionable. Harsh enforcement of stringent standards will cause predictable injury to the economy whereas significant reductions in the peak ground-level ozone concentrations in all urban areas are doubtful both in quantity and in effect. Which will have the greater consequence to public health, a predictable decline in the nation's standard of living or questionable reductions in peak ground-level ozone concentration (if any, wherever they may occur)?

It seems to me that public health correlates more strongly with a healthy economy than it does with the kind of reductions in diesel exhaust emissions targeted by the EPA's new regulations. If the EPA carries out its threat to enforce stringent new emission standards for diesel-powered vehicles by levying heavy fines on the manufacturers for non-compliance, the adverse effect on the economy is a certainty while the potential benefits to air quality are doubtful. Punishment of the engine companies for the failure of their superb and irreplaceable prime movers to meet arbitrary emission requirements seems ill-informed and counterproductive for society as a whole.

I would be interested in your opinion on the scientific validity of the following claims reported by the Times writer:

"...diesel pollutants...contribute to thousands of cases of asthma, heart disease, and premature deaths every year. Diesel vehicles are responsible for 34 percent of all nitrogen oxide emissions in the United States, although they are only about 12 percent of all vehicles. In Southern California, 71 percent of the airborne cancer risk is attributed to the 2 percent of vehicles that are diesel-fueled."


"...The environmental agency estimates that the requirement [to require diesel trucks and buses to cut emissions by 90 percent by 2007] could prevent 8,300 premature deaths annually."

If you knew how the EPA derives its emission inventory figures, you would dismiss the rest of the numbers. But assuming those inventories and their extrapolations to air quality effects are correct, where do the health effect numbers come from and how are they corroborated? They sound scary as presented, but just how severe is the risk of airborne cancer in Southern California? 71% of how many of what kinds of cancers? Does Administrator Whitman read your editorials?

Here is the view of one astute editor on the subject:

"The whole aim of practical politics is to keep the populace alarmed and thus clamorous to be led to safety by menacing it with an endless series of hobgoblins, all of them imaginary."
H.L. Mencken

Alvin Lowi, Jr., P.E.
Member, Society of Automotive Engineers
Rancho Palos Verdes, CA