But as bad as this winter has been and last summer was, "Utah's air has been much better the last 10 years than it was before that," insisted Bob Dalley, state director of air monitoring.

"The last decade or so we've done a pretty good job," Pope agreed. "Things have improved, and the state deserves credit for it. But I don't think we can say we're done with it, that (the problem) is over."

Dalley agrees, warning it will get worse in the years ahead. "Because of urban sprawl, increased population and the increased distance we drive, sometime within the next 10-year period the trend of improvement we see will have switched," he said.

That predicted trend, which is not unique to Utah, is why state and federal regulators are pushing hard to promote cleaner-burning vehicles, more mass transit and cleaner industry.

The years ahead portend major changes as more and more environmental mandates are passed down from Congress or from federal agencies like the EPA. Critics of mandates claim these changes will come with steep costs to consumers and taxpayers.

For example, local governments are now grappling with how to comply with federal standards limiting the amount of polluted rainwater that is allowed into storm drains. And farmers, dairymen and feedlot operators are faced with tough restrictions on pollution from fertilizers and animal wastes that wash into local waterways.

And recently, the Clinton administration approved new regulations that are expected to cut air pollution from heavy-duty trucks and buses by more than 90 percent over the next decade.

The Bush administration has put those regulations on hold pending further review. But if the new federal standards are approved, it will require new large trucks and buses to meet stringent tailpipe emission limits and direct refiners to produce virtually sulfur-free diesel fuel.

It is a standard not unlike the lead-free gasoline requirement implemented more than two decades ago for most motorists. And like the lead-free gas regulation, the new diesel rules come with plenty of grumbling, mostly from the trucking industry that warns increased costs will inevitably be passed along to consumers.

But not everyone is crying the blues. Lynette Phillips, Utah Department of Transportation spokeswoman, said it's too early to tell exactly how the new legislation will affect the state. "If it does impact us, we'll have to deal with it," she said. "Anything that will help the environment, we're in favor of."

It's a gas

The diesel regulation could have positive effects beyond less sulfur in the air.