Recent nighttime temperatures in the 30s and 40s mean the air in many Maine neighborhoods soon will carry one of the telltale signs of winter in New England: the sweet smell of burning wood.
But health and environmental officials say there is potential for increased air pollution problems in isolated spots as more Maine homeowners attempt to fight off record-high oil prices by lighting up the old stove or fireplace.
“We expect that there will be more air pollution this year,” said Ed Miller, chief executive officer of the American Lung Association of Maine.
What is extremely difficult to predict, Miller and others said, is how much pollution that additional wood burning will create — and whether Mother Nature will help minimize the effects or conspire to cause health problems on the ground.
“The big picture is that under most weather conditions Maine’s air quality is pristine,” said state Environmental Protection Commissioner David Littell. “Winter air quality is usually very good in Maine.”
New wood stoves as well as wood pellet stoves are flying off the shelves at retailers across the state — that is, if there are any left in stock to sell.
That’s because even with recent increases in the price of pellets and firewood, these homegrown fuel sources still typically offer more burn for the buck than $4-a-gallon heating oil.
Modern wood stoves certified by the U.S. Environmental Protection Agency or pellet stoves are not really a concern when it comes to air pollution, according to state officials. While they emit more particulate matter — or soot — than oil-fired or natural gas furnaces, they are still relatively clean and highly efficient.
Air pollution becomes a concern, officials said, when you’re talking about inefficient fireplaces and those old wood stoves that, until this year, have been relegated to the role of kitchen furniture.
Older wood stoves and fireplaces are often hundreds, even thousands of times dirtier than oil and gas-fired furnaces. The same goes for many outdoor wood boilers bought before state emissions standards took effect this year.
“My sense is a lot more people are trying to buy new pellet stoves … and clean-burning, EPA [certified] wood stoves,” Littell said. But the harsh economic reality is that an untold number of homeowners will feel forced to use older, dirtier wood stoves more than they have in years past, Littell said.
Adding to air quality concerns, firewood sellers are quickly running out of the dried, seasoned wood that burns most cleanly and efficiently. Burning green wood not only produces more air pollution, it also releases more substances that can raise the likelihood of chimney fires.
Whether those dirtier heat sources will trigger air quality problems depends largely on weather, topography and housing density.
Even a light breeze will help disperse smoke, or at least lift it far above the breathing zone. The problem occurs during what’s known as an “inversion” when a layer of warmer air forms above the colder ground. Inversions are most common on clear, dry and cold days or nights when there is little to no wind.
Jim Brooks, director of the Maine Department of Environmental Protection’s Bureau of Air Quality, said he expects to see some air quality “hot spots” in urban areas.
“Out in rural Maine where there are not many people around, you’re not going to damage air quality,” said Brooks. “It’s in the urban areas where you have a concentration of folks [burning wood] and you have an inversion.”
Littell said air quality monitors around the state would watch for problems. While uncommon, air quality advisories are occasionally issued for specific areas in Maine during winter. Increased wood burning combined with inversion conditions could lead to more air quality advisories, Littell said.
The American Lung Association of Maine is working with the Maine Center for Disease Control and Prevention on a large survey of homeowners about their heating intentions for the coming winter.
The lung association’s Miller said that report, slated for release in early October, would help shed light on how many households plan to increase their reliance on wood for heat.
But Miller acknowledged that air pollution is not the most pressing issue many Mainers will face this winter.
“It’s not good for your health to be cold either,” Miller said. “The lung association’s position is we want to see people burning wood as cleanly and safely as possible.”