Nearly a dozen manufacturers, including one from Millinocket, have agreed to sell less-polluting outdoor wood boilers by spring under a voluntary program negotiated by the U.S. Environmental Protection Agency.

Federal regulators announced the voluntary program Monday, the same day that a coalition of air quality officials from Northeastern states unveiled model rules that would enable governments to clamp down on pollution emissions from the controversial furnaces.

All of this comes weeks before the Maine Legislature is expected to take up several measures dealing with the boilers, which have grown in popularity in recent years as homeowners seek cheaper fuel alternatives to heating oil and natural gas.

Under the EPA’s voluntary program, 10 manufacturers have agreed to begin selling at least one boiler model by spring 2007 that emits no more than 0.6 pounds of particulate matter per million British thermal units (BTUs) contained in the wood fuel.

That represents a 70 percent reduction in emissions over most models on the market today, according to the EPA. The participating manufacturers, which include Millinocket-based Clean Wood Heat LLC, account for more than three-quarters of all outdoor wood boilers sold in the U.S.

Clean Wood Heat says one of its Black Bear models already burns as cleanly as some EPA certified indoor wood stoves which must meet much more stringent requirements than the voluntary ones for outdoor boilers.

The Northeast States for Coordinated Air Use Management, meanwhile, released model rules Monday that will enable states and local governments to require even cleaner boilers. Several Maine communities, including Millinocket, have adopted or are considering restrictions on the wood boilers.

NESCAUM’s model rules, if enacted by a state or community, would ban the sale or installation after March 2008 of boilers that emit more than 0.44 pounds of soot per million BTUs. The rules also propose an even tougher emissions standard after March 2010.

“This partnership, along with efforts from Northeast states, will provide consumers with a choice to purchase cleaner outdoor wood heaters and communities with tools to take action now,” Bill Wehrum, acting assistant administrator for EPA’s Office of Air and Radiation, said in a statement.

David Littell, commissioner of the Maine Department of Environmental Protection, described the EPA’s voluntary standards as a step in the right direction but likely still too loose for the state’s purposes.

The DEP is seeking legislative authorization to begin drafting rules regulating boiler emissions. The department would likely work from the NESCAUM model, which DEP staff members helped develop, Littell said.

“This is the position that we wanted to be in, to have a common regulatory approach across the Northeast,” Littell said.

It is unclear how the EPA’s voluntary program or NESCAUM’s proposed regulations will affect debate over the wood boilers. Boilers that meet the emissions standards under either scenario, while cleaner than most current models, could still pump significantly more pollution into the air than other furnaces.

Under the EPA’s voluntary standards, for instance, boilers could still emit roughly 95 grams of particulate matter, or soot, per hour. By comparison, new indoor wood stoves are required to emit between 4 and 7.5 grams of soot per hour under EPA standards. Oil and natural gas furnaces, on the other hand, generally emit less than 0.02 grams hourly.

Norm Anderson with the Maine chapter of the American Lung Association said his organization wants any rules to govern both new and existing boilers.

“We’re reviewing both of these … but concerns still remain at least with the EPA program and possibly with the NESCAUM one,” Anderson said.

Representatives of boiler manufacturers praised the EPA program.

Jack Goldman, president of the Hearth, Patio & Barbecue Association, said in a statement that manufacturers are committed to selling a clean product.

“This new partnership effort, combined with proper installation and following the industry’s best burn practices, will provide consumers with cleaner heating appliances that use a renewable, affordable energy source,” he said.