Cleaner air through the reduction of diesel truck idling is the goal of a resolution introduced Thursday by Dane County Supervisor Brett Hulsey.

The measure, which now moves to County Board committees for study and public hearings, would ban unnecessary truck idling for more than five minutes per hour in unincorporated areas where the county has jurisdiction.

But Hulsey and other County Board members were urging cities and villages "to follow the county's lead" in approving similar measures, so that the prohibition eventually could apply countywide.

"This is one of the most cost-effective things we can do to reduce soot pollution," Hulsey said Thursday. "We're starting with the easy stuff."

Pollution-reduction efforts are especially important now, Hulsey said, after the Environmental Protection Agency last month judged Dane County to have unacceptable levels of fine particulate matter, or soot, caused largely by coal-fired power plants and diesel engines.

That matters because soot pollution has been linked in scientific studies to health problems such as asthma, lung disease and heart attacks. To date, Hulsey said, 20 states and more than 20 cities and counties have idle-reduction laws in place to reduce vehicle emissions and save on fuel costs, with the widespread support of public health experts.

"I want to use this resolution to educate people more about diesel idling," Hulsey said.

Thomas Howells, president of the Wisconsin Motor Carriers Association, said the trucking industry generally supported efforts to reduce idling. It's part of a nationwide trend, he noted, and the industry likes less idling because it saves fuel and cuts down on emissions.

But Howells said he'd have to see the fine print before knowing if the trucking association could back Hulsey's proposal.

"We'd have to take a look at the details," Howells said. "There are some exceptional circumstances where it isn't realistic to not idle."

For example, Howells said, when a refrigerated truck has parked somewhere to load or unload frozen goods, it may be necessary to idle the entire time to keep the load cool.

Hulsey said trucks could do that under one of eight exceptions provided in the proposal. The other exceptions would allow idling of up to 15 minutes per hour when the temperature is above 80 degrees or below 40 degrees -- as well as unlimited idling if it's below minus 10.

Emergency vehicles, airport support equipment and vehicles being serviced or repaired also could idle with no limits, the proposal says, and the limits would be suspended when truck drivers are in traffic conditions beyond their control.

Violations of the ordinance would carry a $50 fine.

Hulsey noted the hearings would provide plenty of opportunity for input from those for or against the proposal.

"We also want to work with the motor carriers," Hulsey said. "If they have other changes (to suggest) in the language, we'll certainly be happy to work with them."