PORTLAND – The American Lung Association of Maine sounded a warning Monday about what it called an emerging health hazard – the growing popularity of outdoor wood boilers.

Asserting that pollution from outdoor wood boilers is extremely high compared to other wood burning devices, the association called on state regulators to require that the boilers meet the same emissions standards that the Environmental Protection Agency sets for wood stoves.

Outdoor wood boilers are detached units used for home heating. Heated water can be pumped into the home through underground piping and linked to existing heating systems.

Edward Miller, the lung association’s CEO, told reporters at a wood stove retail shop that the boilers are inefficient and dirty.

“Outdoor wood boilers not only burn at low temperatures and smolder, they are big enough to burn trash, commercial waste, animal carcasses and other dirty fuels unsuitable for residential combustion – all unregulated and all putting the health of the owners and neighbors at serious risk,” he said.

Kevin Macdonald, an environmental specialist in the Department of Environmental Protection’s air quality bureau, said the agency was looking at the devices.

“I know that internally we have been having discussions about how to approach these outdoor wood boilers,” Macdonald said. “In some situations they could very well be problematic.”