UW News

November 7, 2002

In the winter, smoke from wood burning pollutes

The evenings get chillier and darker. There’s a wisp of wood smoke in the air and people are looking forward to some crackling fires on cold winter nights.

But if you live in one of the Northwest’s urban or metropolitan areas, you may need to take another look at that glow from the fireplace and another sniff at that wisp from the woodstove.

“Overall, we quite strongly recommend that people quit burning wood in urban settings,” says Dr. Jane Koenig, professor of environmental health at the University of Washington’s School of Public Health. “The pollution and particles from wood smoke add to the overall burden in the air from traffic congestion and other sources. In the winter, wood smoke is a significant portion, estimated at between 35 and 45 percent, of the pollution load in the air.”

Restricting wood burning is one of several still-voluntary measures citizens are being asked to take in order to reduce overall air pollution, Koenig notes. Only when there is a temperature inversion, or similar weather pattern that keeps pollution from dissipating, are people legally prevented from burning wood in the Puget Sound area. An exception is made for homes without other heat sources.

Many people buy newer wood stoves with catalytic converters to reduce the stove’s emissions. They do make a difference, Koenig says, but tend to clog up over time and lose their effectiveness.

And if you are using a wood stove without a converter? Well, Koenig recommends that you take it out and replace it with a gas or electric “log” or just use the space for a nice new bookcase.

Occasional fireplace use is not such a big problem, because it is more intermittent. Still, if many houses in a neighborhood have fireplaces, the pollution load on a weekend evening can be enough to cause problems for children with asthma and others with cardiac or lung conditions.

Koenig’s original studies of air pollution, begun more than 20 years ago, were with asthmatic children. People with asthma have airways that are easily irritated by air pollution, second-hand smoke or other allergens.

“The evidence has convinced me that dirty air is harming people and that wood smoke is a significant factor in that,” she says, noting that people respond differently to a certain level of air pollution depending on their age, activity, immune system, and medical conditions. People with lung disease, such as chronic obstructive pulmonary disease, and with asthma are most at risk.

A recent study done at Harvard School of Public Health and reported in the journal Epidemiology has revealed that increased air pollution may also be linked to higher death rates from diabetes and heart disease — a finding that

“We know that wood smoke causes airway irritation, and the body can turn on an inflammatory response to inhaling some compounds, or just to the irritation,” Koenig says. “This inflammation, especially if it is long-term, may be causing several other effects on health.”

Koenig and her colleagues are continuing their research on the effects of wood smoke. Among the current goals are better ways to determine how much of the pollution a person inhales can be tied to various sources, and the relative effects of short-term and long-term exposure.

For those who feel nostalgic about the romance of wood smoke, Koenig has this thought: “Unfortunately, there are a lot of things people used to do that just don’t make sense in a crowded urban environment today. People used to drink out of the creek, too, and nobody would want to do that now. The only way we could handle more wood burning would be to get rid of our cars.”