A white paper on the so-called "tailpipe tax" was generated years ago. But state policymakers haven't considered it - in fact, it's unlikely they saw it despite its potential to help clean up the air without increasing costs to business or government.

Doug Macdonald, the Utah Tax Commission's former chief economist, generated the numbers back in 2001, after one bad pollution season. He dusted off the white paper after another serious episode in 2004.

"It ought to be out there on the table as one of the ways to reduce emissions," he said, "and to reduce the health problems we have because of this haze we have here."

Both pollution control advocates and anti-regulation proponents have quarrels with Macdonald's idea. But others agree that it's smart to target vehicles - instead of industry - for the next round of air pollution reductions.

This is how a tailpipe tax would work: The tax would be based on the exhaust tested during annual emissions inspections, when hydrocarbons, nitrous oxides and carbon monoxide are measured.

The more pollution, the higher the tax. It could supplant the age-based vehicle registration fee now used and raise just as much money, about $68 million.

Macdonald points out one big downside: Tailpipe taxes are regressive, falling heaviest on people who drive older cars that tend to pollute more. But he said there are simple ways to address this problem, including giving people with high-pollution cars first dibs on the state's surplus fleet.

Cars and trucks account for about 55 percent of the pollution - including the dirty buildup seen for more than two weeks in January. Since estimates in Utah and California suggest that the dirtiest 10 percent of vehicles can be blamed for about half the pollution, getting those dirty cars off the road would go a long way toward improving air quality.

Macdonald's study was deep-sixed so effectively that when The Tribune filed an open-records request for it several weeks ago, the State Tax Commission denied its existence. Then Thursday, Commission spokesman Charlie Roberts said a copy was belatedly discovered in computer archives.

At the same time, he attempted to put as much distance as possible between the Commission and the study.

"Since the Tax Commission evaluates fiscal impacts of [proposals] - rather than endorsing or opposing specific tax policies - the Commissioners never requested, approved, considered or accepted it," Roberts said.

Macdonald realizes many Utahns would probably object to the idea at first, but at the same time, many recognize that northern Utah residents suffer heart disease, lung disease and other health costs because of air pollution.

"To me, it's ridiculous we can't find a solution," he said.

"Let's challenge the Legislature to do something proactive, rather than wait for the [U.S. Environmental Protection Agency] to make the state clean it up."

Rep. Roger Barrus, R-Centerville, says the tailpipe tax appears on first blush to be punitive and an attack on personal freedom. Instead, he said, the state focuses on positive incentives to conserve energy and lower pollution.

He points to a pending bill by Rep. Roz McGee, D-Salt Lake City, that provides tax breaks for people who use energy-efficient, low-emission vehicles.

"If you try to force people to do things," Barrus said, "it's not as effective."

This appears to be the tactic many states are using, according to Adela Flores-Brennan, an environmental policy specialist at the National Conference of State Legislatures, a kind of trade group for lawmakers.

"There are lots and lots of bills this year across the country for credits for clean-burning vehicles" and other pollution-cutting measures, she said. "They're basically centered around creating incentives for consumers and retailers."

Rick Sprott, director of the Utah Division of Air Quality, hadn't heard of a tailpipe tax being proposed for Utah or other states. He questions how practical it would be to base a tax on a brief snapshot of vehicle emissions. He also questions its regressive quality.

The state is currently looking hard at ways to reduce emissions to meet new, tougher standards for fine particle pollution - the stuff known for fouling Utah's air in the winter. But it appears that the changeover to new cars and cleaner fuels will help Utah go far in meeting that standard, said Sprott.

"It sounds good, in theory," he said of the tailpipe tax. "But in practice, you could get into a huge amount of problems."

While there are critics like Sprott and Barrus, a number of Utahns would welcome another option for dealing with the state's air pollution problem.

Mike Jerman, vice president of the Utah Taxpayers Association, had not heard of the tailpipe tax idea but found it intriguing. His group, a lobbying organization largely funded by the state's big businesses, is advocating a similar user tax to address highway congestion.

"This is one of those issues . . . environmentalists and fiscal conservatives can work together on," he said.

Tim Wagner, energy specialist with the Utah Chapter of the Sierra Club, said the tailpipe tax concept might prove useful but it would have to address the financial burden placed on those least able to afford it.

"Spreading the responsibility for cleaning up our air to all Utahns is a good thing," he said.

"We're all part of the problem and are all therefore part of the solution."

Holladay resident Kathleen Bourne also supports more attention by state leaders to air pollution. She recalled how frustrated and helpless she felt this year trying to cope with the January pollution. She wants state leaders to do something - yesterday.

"Anything to reduce pollution should be looked at seriously," she said. "We're all in this together. We've all got a problem here in this valley."

fahys@sltrib.com