Pollution Curbs Put on Wood-Burning Stoves

Harry Locker enjoys the pleasant aroma of wood smoke on cold New England mornings as much as anyone, even knowing it can be unhealthy.

Locker, a graduate student at Dartmouth College, has for four years been researching ways to determine how much wood smoke contributes to air pollution, something that monitoring agencies in Vermont, Maine and New Hampshire say they need to assess the problem.

Though wood-smoke pollution is “not the worst environmental situation in the world,” Locker is glad nonetheless that federal emissions standards for new wood-burning stoves take effect this summer.

The Environmental Protection Agency regulations, adopted last week, mandate a sharp reduction in particles emitted by stoves manufactured after July 1.

Sellers have until 1990 to exhaust their supplies of unregulated stoves, and tougher restrictions on particles take effect in 1990 for producers and 1992 for sellers.

The new stoves, some already certified and being sold, reduce emissions by improving combustion efficiency. Some use design improvements; others have a catalytic combustor described by the EPA as “in effect, a smoke afterburner.”

Standards are tougher for catalytic stoves because the catalytic elements--typically platinum or palladium bonded to a ceramic backing--deteriorate with time.

Both approaches add to the cost of a stove--about $200 for catalytic models and $120 for non-catalytic ones. But there are benefits: the new stoves burn less wood to produce a given amount of heat. They also emit less creosote, which builds up in chimneys and must be cleaned out periodically to avoid chimney fires.

“It’s true that the price that you see on the showroom floor will go up a little bit, but you’ll make it back,” said David Doniger of the Natural Resources Defense Council in Washington. The EPA agrees, estimating $29 million in savings in five years for consumers nationwide.

Smoke from wood-burning stoves is considered by some scientists to be northern New England’s worst home-grown air pollution problem. Wood smoke pollution also is prevalent in parts of the West.

One component of wood smoke, polycyclic organic matter, contains carcinogens. Locker estimates that half of such compounds in the air come from wood-burning stoves.

In addition to causing cancer, wood smoke contains carbon monoxide and small particles that lodge deep in the lungs and can lead to respiratory and cardiovascular problems.

But the health risks of wood smoke in northern New England have been difficult to gauge. Monitoring agencies not only can’t determine how much air pollution is from wood-burning stoves, but they lack health risk assessments for compounds in the smoke, making it impossible to accurately assess the dangers of exposure, said Norman Anderson, Maine’s assistant state toxicologist.

Oregon discovered wood smoke as a significant pollutant only after it had clamped stringent emissions controls on industry and still couldn’t meet federal Clean Air Act standards.

After discovering that much of its pollution was caused by residential wood-burning, Oregon passed state emission controls for stoves that took effect in mid-1986. Colorado followed on Jan. 1, 1987.

With more state and local restrictions looming, stove manufacturers asked the EPA to set federal regulations. “They wanted a federal standard so badly they would accept a good one,” Doniger said.

The immediate impact of the regulations on pollution will be negligible.

“If you have an area with wood-smoke problems that you want to mitigate, these regulations are not going to do that,” said Andrew Smith, staff scientist for the Natural Resources Council in Maine.

The regulations don’t affect fireplaces or wood-burning furnaces and boilers. And they don’t affect the millions of stoves already in service and expected to have useful lives of 10 to 20 years.

Still, 400,000 to 800,000 new stoves are sold each year, Doniger said, and since most being used now were bought in the energy crisis of the 1970s, they are aging.

The catalytic stoves require attentive operators to work effectively, said Thomas Noel of New Hampshire’s Air Resources Division. Colored paper contains heavy metals that can foul combustors in much the same way that leaded gas affects a car designed to burn unleaded. The devices must be replaced periodically.

A recent study by the Coalition of Northeastern Governors indicated that some new stoves--with and without catalytic combustors--do not significantly reduce emissions once they are installed in a home.

Problem Less Serious

Noel and Vermont’s air quality planner, Richard Poirot, question whether people will make the effort to operate the stoves properly.

“There’s a certain perception that this is the federal government entering into their living room and it isn’t even doing anything about the Midwestern power plants,” Poirot said. The reference was to northern New England’s principal air pollution concern, acid rain caused by industrial pollutants drifting in from the Midwest.

Though more than 40% of the region’s residents burn wood to heat their homes and wood smoke can comprise 40% of air pollution in some areas, Poirot said, geography and climate make the pollution less serious than in Western states.

Weather experts say wood smoke pollution becomes most acute when an inversion of warm air traps smoke in valleys. Though northern New England has many valleys, they are shallower than those in the West, and the legendary abrupt changes in New England weather mean that most inversions end quickly.

Air quality is monitored at 24-hour intervals, and officials say that no violations of federal air quality standards have yet been attributed to wood smoke in northern New England.

“It’s one thing to say we don’t violate this federal standard and it’s another to say we don’t have a problem,” Poirot cautioned.

Alex Driessen, an environmental consultant and volunteer with the New Hampshire Lung Assn., is puzzled by the attention being given wood smoke pollution.

“It’s out of priority. I think it’s a non-issue issue,” Driessen said. He said other pollutants are produced in greater volume, such as auto emissions, are a more pressing issue, along with acid rain.

But Locker, for one, is pleased with the EPA controls--even though he also wants to put a wood-burning stove in his house.

“There’s still a certain amount of romantic attraction about wood-burning” he said.