With rising fuel costs, outdoor wood boilers have become increasingly popular in Maine, prompting complaints from one end of the state to another and a patchwork of local bans and restrictions. To reduce pollution from the smoky furnaces and to have one set of standards statewide, the Department of Environmental Protection has proposed adopting federal rules for new boilers in Maine. This is a good start, but the board also needs to ensure that emissions from boilers already in use are also reduced. Otherwise communities will continue to pass local moratoriums and bans.

The sale of outdoor wood boilers in Maine tripled between 2004 and 2005, while complaints to the DEP have gone from two in 2004 to 50 now on file. The boilers, which are used to heat water and provide heat, don’t use catalytic emission control devices as most indoor wood stoves do. They also are built with short smokestacks, which keeps smoke near the ground, and with big fire boxes, which allows owners to burn all sorts of things that wouldn’t fit into a wood stove. These problems are exacerbated because the units often are used in residential neighborhoods.

The average wood boiler emits more than 70 grams of particulate pollution per hour, more than 15 times the Environmental Protection Agency’s standard for indoor wood stoves. The most polluting units emit more than 300 grams per hour. Particulate pollution worsens asthma and is linked to lung cancer and other cardiorespiratory diseases.

The EPA recently developed voluntary standards for wood boiler emissions. Ten manufacturers agreed to sell boilers, beginning this spring, that emit no more than 0.6 pounds of particulate matter per million BTUs of heat input, a 70 percent reduction in soot emissions over most models now on the market. Allowable emissions will drop to 0.32 pounds per BTU in 2010.

The DEP has proposed that these standards become mandatory in Maine, as early as this fall.

The proposed rules, which are the subject of a public hearing before the Board of Environmental Protection on Aug. 16, also create minimum setback requirements and smokestack heights for new boilers, with larger setbacks required for boilers that don’t meet the new emissions standards.

For existing boilers, those that create visible emissions that cross property lines for more than 15 minutes in an hour would be designated as a “nuisance.” The DEP is charged with working with boiler owners and manufacturers to resolve these problems, through boiler improvements, taller stacks and other modifications. The department will provide monthly reports on problem boilers to the Legislature’s Natural Resources Committee.

This information will enable lawmakers to determine if more needs to be done.

Making new boilers cleaner and assuring they are properly sited, while working to clean up older models, are positive steps.