Air Quality Diminishes As More Drivers Speed

Despite advances with cleaner-burning vehicles, exceeding the speed limit increases pollution.

This summer a record number of Americans will load up the minivan, pile in the kids, and take to the open road.

Unfortunately, they'll also speed.

Fast driving not only burns up more fuel and makes highways less safe, it also creates more pollution. Speeders are slowing America's antismog progress. The faster they go, the more foul stuff is put in the atmosphere.

"Nationwide the increase in emission levels is significant," concludes a 1997 analysis by the federal Environmental Protection Agency (EPA). It estimates single-digit increases in passenger-vehicle emissions since the United States repealed national speed limits. In fact, the figures are almost certainly higher because Americans break those higher, state-mandated speeds.

Worse, even if the EPA knew how many drivers speed, it doesn't know how bad the effect is. Its emissions standards test cars at a top speed of only about 59 miles per hour. The agency is adding a supplement test that will look at high speeds and sudden acceleration of new cars, but that won't take effect until 2000.

In the meantime, speeders own the road and, it seems, the air (although a few drivers are making a voluntary decision to slow down).

This summer Americans are expected to hit the road in record numbers, thanks to high consumer confidence and low gas prices. A survey by the Travel Industry Association of America and the American Automobile Association estimates that Americans will take 251 million vacation "person-trips" during June, July, and August, up 3 percent from last year, which was also a record. Four out of 5 Americans drive to their summer-vacation spot. It's unknown how many of them will speed. But just by increasing highway speeds from 55 miles per hour (the old limit) to 65 miles per hour, the average passenger car spews out nearly 10 percent more nitrogen oxide (NOx), 56 percent more volatile organic compounds, and 153 percent more carbon monoxide, according to the EPA.

Of course, cars don't drive those speeds all the time and other sources spew out the same smog-inducing pollutants.

"It's certainly a negative effect," says Eldert Bontekoe, the EPA's expert on vehicle certification. "The vehicles would have had lower emissions at the lower speeds. [But] my personal estimation is that [the increase] is just at the margins."

"Speeding itself is significant but not huge," adds Marc Ross, an emissions researcher and professor of physics at the University of Michigan in Ann Arbor, Mich. But add in the other problems of vehicle emissions - aging motors, cars that aren't maintained - and the pollution effect is compounded. "All the loopholes, all the failures of vehicles to behave on the road as they do in the tests ... remain a big deal."

Automakers can and will sharply reduce carbon monoxide and organic compound emissions under the more stringent EPA standards for cars built after 2000. Carmakers can do this because, among other things, they're building more durable and reliable emissions systems and they're moving away from a technique, called "command enrichment," in which under some circumstances they'd push more gas to the engine whether it needed it or not, Professor Ross says.

But "the NOx is harder" to control, he adds, because it's created when an engine gets hot. And an engine usually gets hotter the faster it goes. Highway vehicles contribute about a third of the nation's NOx emissions.

Although the new standards will tighten up NOx emissions somewhat, the bigger breakthrough is that for the first time new cars will be tested for emissions at higher speeds and during quick acceleration. The standards take effect after the turn of the century.

In the meantime, it's up to individuals to ease off the accelerator.

One of them is Ben Shipman, a manufacturer's sales representative in St. Louis.

"It's been really incredible," he says. "In November, I quit cold turkey. And I'm a guy who used to drive 100 [m.p.h]."

"Now I never get tired," he adds. "It's just more relaxed when you're not driving white-knuckled." Of course, he does have to factor in more travel time to reach his destination. And he didn't do it for environmental reasons. But his gas mileage has improved 10 percent, he adds, and that not only saves money, it helps preserve the environment.

What reformed the avid speeder? "I finally realized it wasn't principled," he says.