WASHINGTON – Sport-utility vehicles emitted significantly more pollutants than regular passenger cars, but they were still more likely to pass their emissions tests in 2001, according to a Capital News Service analysis of inspection records.
The reason is simple: SUVs are held to lower standards.
“The sad truth of the matter is there is nothing that can be done about it,” said James Kliesch, a research associate with the American Council for an Energy-Efficient Economy.
The Environmental Protection Agency long ago put SUVs in the light-duty truck category with minivans and pickup trucks, which are subject to less- stringent regulations than cars.
The CNS analysis is based on test results for 5,637 vehicles, including cars, SUVs and larger trucks, that were subjected to full-length emissions inspections in 2001. State officials consider the four-minute test better for comparing emissions between vehicles, and they gave it to a portion of the more than 900,000 vehicles tested that year.
The analysis, using definitions of SUVs provided by the National Automobile Dealers Association and Edmunds.com, found that the popular vehicles emitted 42 percent more greenhouse gases and 20 percent more ozone precursors than passenger cars in the sample. But only 8 percent of SUVs in the sample failed, compared to 11 percent of passenger cars.
The SUVs were able to pass because their higher emission rates fell within levels set by the state, which lets SUVs emit, on average, more than twice the carbon monoxide, about 50 percent more hydrocarbons and nearly 30 percent more nitrogen oxide.
“Twenty years ago they (SUVs) were primarily used by small businesses, not by commuters, so the EPA cut them a break,” said Marcia Ways, chief of the Engineering Division for Maryland Department of the Environment.
Those three chemicals — carbon monoxide, hydrocarbons and nitrogen oxide — all contribute to ozone problems, according to EPA and state environment department officials.
The tests showed a range of emissions even among SUVs.
The Toyota 4Runner pumped out less of all three ozone precursors than the Nissan Pathfinder, which was better than the Chevrolet Blazer. But those three models were relatively clean compared to the Ford Bronco and Chevrolet Suburban, which spewed, on average, 98 percent more carbon monoxide, 74 percent more hydrocarbons and 110 percent more nitrogen oxide than the general class of SUVs.
“I don’t think in the big picture it has that much difference,” said Tim Armstrong, 44, of Upper Marlboro, who drives a Ford Explorer.
Experts on vehicle emissions disagree.
“If this SUV thing had been something of a margin thing, then it wouldn’t have added up to anything on a regional scale,” said Ronald F. Kirby, transportation planning director for the Metropolitan Washington Council of Governments.
But a walk through almost any neighborhood makes it clear that the popularity of SUVs has reached far beyond the margins. Passenger cars fell from 63 percent of all vehicles on the road in 1990 to 50 percent in 2000, with most of the difference being made up by SUVs, Kirby said.
Put another way, while the number of cars on the road in Maryland has risen 4 percent since 1990, the number of light-duty trucks has increased at 56 times that rate, Ways said.
The popularity of SUVs has caught planners by surprise. Kirby said that when local officials used a new EPA computer model for gauging emissions, they found that SUVs had added 8 tons of nitrogen oxide to the atmosphere, 7 percent more than their previous estimate.
“It was enough to give us a problem,” Kirby said.
It is a real problem, as planners try to craft emissions guidelines that will let the state meet federal air-quality standards. Both the Washington and Baltimore regions are currently in “severe” non-compliance with the Clean Air Act, and stricter federal guidelines are on the horizon.
Kirby and Ways see a bright light on the horizon. Beginning with model year 2004, the EPA is phasing in “Tier 2” regulations that will basically hold SUVs under 8,500 pounds to the same emissions standards as passenger cars. This will affect the vast majority of SUVs, Ways said.
“It depends on the fleet turnover, but within the first three to five years you should see some impact,” Ways said.