Wood stoves: a hazy debate

Central Oregon wood stoves contribute to toxic air

By Tara Bannow / The Bulletin / @tarabannow

Dave Stalker isn’t the only one in his Bend neighborhood with a wood stove. And on some days — such as during last week’s bout of stagnant air — that’s all too obvious.

“It’s pretty bad when you’ve got a bunch of people with belching wood stove chimneys in the neighborhood,” he said. “You walk out and you go, ‘It smells like a forest fire.’”

Roughly 1 in 5 Central Oregonians use wood stoves to heat their homes, according to a 2009 Oregon Department of Environmental Quality survey. Many cherish the heat source for the cozy feel it exudes — the sound of crackling wood, the campfire smell — especially on a cold winter’s day. For others, especially those in rural areas, it’s cheaper and more feasible than natural gas or propane and, from a broader perspective, decreases the country’s reliance on oil.

But wood stoves have also received a lot of attention in recent years for their potential to harm people’s health. Experts say the tiny, toxic particles they emit into the air wind up collecting in people’s lungs or flowing through their bloodstreams, causing everything from asthma to cancer or heart attacks.

Increased research has prompted the U.S. Environmental Protection Agency to consider tightening its emissions limits on new wood-burning stoves as well as expanding its existing regulations to include things such as pellet stoves and fireplaces.

Nationally, the EPA says residential wood burning accounts for nearly 25 percent of all cancer risk from air toxins and 15 percent of noncancerous respiratory effects.

“The bottom line is, if someone is burning wood … you’re creating a real pollution hot spot,” said Brian Moench, president of Utah Physicians for a Healthy Environment, a group seeking to educate people about the health effects of wood smoke. “Therefore, you’re creating some real localized victims.”

Problems in Utah

Depending on the weather and the type of wood you use, heating your home with a wood stove for a mere hour could emit the same amount of chemicals into the air as driving your car from Bend to Denver.

That’s according to a University of Utah study cited by the state’s governor in his recent State of the State address, in which he called for limits on residents’ ability to use wood-burning stoves in the winter.

Utah’s Wasatch Front, a metropolitan region in the north-central part of the state, is particularly hard-hit by air pollution, including from wood-burning stoves, due in large part to its topography. Cities are more susceptible to lingering air pollution if they’re within a basin between areas of high elevation. Klamath Falls, for example, is similarly known for its tendency to see periods of stagnant air.

Studying the 35,000 wood stoves in the Wasatch Front, researchers at the University of Utah found that heating one home with a conventional wood stove released an amount of fine particles equivalent to heating more than 200 homes with natural gas. Using an EPA-certified wood stove was equivalent to heating more than 130 homes with natural gas.

Citing that and other research, a group of doctors is calling for a ban on wood-burning stoves. Moench, an anesthesiologist at LDS Hospital in Salt Lake City, said wood smoke can be even more dangerous than secondhand cigarette smoke because its particles are so tiny they can easily seep into neighboring homes in addition to the home they’re heating. Some studies have found the wood smoke concentration in neighboring homes that aren’t burning wood to be 50 to 75 percent as high as the outdoor concentrations, Moench said. Older homes typically have less of a seal between indoor and outdoor air, he said.

Moench draws parallels between society’s slow acceptance of the dangers of wood smoke with that of cigarettes, which it took 40 years of research to regulate.

“There is a big gap between the medical literature and published articles and society’s acceptance of an issue,” he said, “and that’s probably the case here as well and it may even be the case with physicians.”

Regulations in Oregon

In 1986, Oregon became the first state in the U.S. to require that all new wood stoves meet emissions standards. The EPA launched a similar testing program in 1988 that applied nationwide. When homes are sold, Oregon’s law requires that any uncertified wood stoves inside be removed and destroyed.

Oregon also has a program that constantly monitors air quality and issues green, yellow and red ratings that can correspond with local calls to cease wood burning, said Carrie Capp, who coordinates the Oregon Department of Environmental Quality’s HeatSmart Program, which regulates wood stoves.

“It’s a source that is close to where we work and live and play and breathe, so it’s something we can go after, have a collective impact on reducing a pollution source that’s in our immediate environment that we’re exposed to every day,” she said.

Air quality can be dramatically worsened by weather inversions, when cold air gets trapped low to the ground and warm air rises high into the atmosphere, which is the opposite of what usually happens. During inversions, emissions get trapped near the Earth, and smoke from wood stoves is known to hover over homes.

Bend saw 44 days of weather inversions between Nov. 1 and Feb. 26, said Dennis Hull, a National Weather Service meteorologist. Hull said he couldn’t comment on how that compared with other years but said about one-third of the winter days being inversion days seemed high. Most of the DEQ’s air pollution warnings last year were for Southern Oregon, but it issued warnings for areas that included Central Oregon on Nov. 21, which was also a weather inversion day.

Air-quality regulations are necessary, Capp said, because the particles in wood smoke can be 2.5 micrometers in diameter or smaller. (For comparison, a human hair is about 70 micrometers across.) When inhaled, those particles carry carcinogens like benzene and black carbon deep into the lungs, causing everything from premature death in people with heart or lung disease, irregular heart beats, aggravated asthma, decreased lung function and increased respiratory symptoms such as coughing and difficulty breathing, she said.

Michael Dourson, director of the Toxicology Excellence for Risk Assessment, a nonprofit group that researches toxicity data, said while there’s no question that wood smoke is toxic, banning it altogether is the wrong strategy for reducing harm.

“At some level, if you drink too much water, you will kill yourself,” he said. “Just banning things because they’re wood smoke or water or vitamin C or potato chips, just saying, ‘We’re going to ban it’ is not the right approach to things. … All chemicals are toxic and there are safe levels for all chemicals and there are safe levels for wood smoke.”

Not enough evidence for local doctors

Allergists in Bend often hear complaints from patients who say the wood smoke that’s common in winter exacerbates their asthma.

When it comes to allergens like dogs or pollen, doctors can run tests to pinpoint the exact source of the problem, said Dr. Adam Williams, an allergist at Bend Memorial Clinic. Wood smoke, however, is an irritant, which doctors can’t test for.

“To an allergist, those are frustrating things, because we want to be able to test for what it is,” Williams said.

Ripdeep Mangat, an allergist at the Allergy and Asthma Care Center in Bend, has the same gripes about wood smoke. He said he often asks patients whether they have or live near a wood stove but hasn’t seen sufficient research on the subject to issue a strong condemnation of the appliances.

If patients say their symptoms are worsened when they’re around wood smoke, Mangat said, he simply tells them to avoid being around wood stoves. He also recommends they carry a rescue inhaler in case an asthma attack strikes.

Likewise, Williams said he’s wary of supporting any regulatory changes around wood stoves until there’s clear data linking the smoke to health problems. In one case, Williams said, he did ask a patient with serious asthma to stop using his wood stove. Once the patient did that, his symptoms improved.

Some research has found little effect from wood smoke on human health. Two Danish studies performed in recent years tested the effects of exposure to large amounts of wood smoke for three hours. Neither found evidence of long-term damage, only the mild inflammation that would be expected.

Asthma in general seems to be worse in the winter, but it’s unclear exactly why that is, Mangat said.

“That might be because the indoor allergens are higher,” he said. “It might be because the air is drier and it might be that they’re exposed to more irritants inside. Any of those are possible. It’s hard to pinpoint which one that is.”

Burn hot, burn clean

Bend resident Heidi Renoud grew up in a house with a big, old cast-iron wood stove. Her family would get the fire roaring before bed and the heat would last well through the night.

That’s not possible any more, now that Oregon law requires new wood stoves be EPA-certified.

“These ones they produce now with all the regulations, you can’t keep a fire overnight,” she said.

Renoud said she’s irritated by all the rules around wood stoves. She’s been using them since she was a kid and knows how to make a proper fire that’s not going to send a cloud of black smoke out of her chimney. She and her family cut the wood themselves and dry it for at least a year before using it. She’s even got one pile that’s been sitting for two years. The Oregon DEQ recommends chopping wood and letting it dry for six to 12 months before burning it.

“It’s a process,” she said. “You have to stay on top of it.”

In 2009, nearly 22 percent of Central Oregonians surveyed said they use a wood-burning stove, and nearly 15 percent said it was their main heat source, according to a DEQ survey. The survey’s central region covered eight counties, including Deschutes, Crook and Jefferson.

Moench, however, said the number of Americans using wood-burning stoves increases about 3 percent per year, a trend he called “disappointing.” Some advocates tout wood-burning stoves as a way to get “back to nature,” he said. Even prominent environmentalists like Bill McKibben, the co-founder of the international climate campaign 350.org, have celebrated the use of wood stoves, Moench said.

Anecdotally, Stalker, of Bend, said he thinks the amount of wood smoke hovering over Bend has significantly decreased from when he first moved to the area in the 1970s. Back then, it was noticeably smoky in the evenings. He said he thinks many people have transitioned to natural gas because it’s easier.

Stalker, who has heated his homes with wood stoves for nearly 40 years, said he thinks people can dramatically reduce the emissions from their wood stoves by simply paying attention to their fires. His mantra is “burn hot, burn clean.” If he notices his chimney is “belching smoke into the neighborhood,” Stalker said it’s because he needs to beef up the fire, either by adjusting the wood or the damper, a device that regulates air flow. He also makes sure not to close the wood stove door until the fire is roaring.

Renoud’s advice is similar: Don’t let the fire smolder.

“It’s either burn hot or it’s not burning at all,” she said.

For Renoud, the decision to buy her two wood stoves for her 4,000-square-foot home about a decade ago was financial. Her electric bills were through the roof. Now, she said she saves about $300 per month to heat her house using the wood stoves.

But Stalker, who buys his wood and supplements his wood stove with electric heaters, said it’s a ton of work and it doesn’t really save money. For him, it’s more of a feeling.

“It’s just a really nice warmth, you know?” he said. “Once you get it really going good, it just permeates the whole place and it’s just really nice.”

— Reporter: 541-383-0304,

tbannow@bendbulletin.com