Your Neighbor’s Wood Stove May Be Killing You
When your neighbor is burning wood, deadly pollutants are inside your house. According to the Washington Department of Ecology, indoor levels of fine particle pollution from wood smoke reach at least 50% to 70% of outdoor levels, even in homes without wood-burning stoves or fireplaces.
Recent studies have shown that fine particle pollution from wood smoke and other sources is more harmful to health than previously understood. A report released by the American Lung Association in March 2001 summarizes the results of more than 800 scientific studies on the health effects of airborne particulate published over the last five years. These include studies of the Seattle area, where wood stoves and fireplaces are the largest source of fine particle pollution.
According to the ALA, the recent studies "confirm the relationship between particulate air pollution, illness, hospitalization, and premature death." Researchers have compiled extensive data on illness and death rates in both large and small cities, and have considered PM10 (particles no more than 10 microns wide) as well as smaller particles and other air pollutants. Laboratory studies have identified adverse physical responses to particulate exposure in both healthy people and people already suffering from heart or lung disease.
The results of several major studies indicate that death rates in Seattle and other U.S. cities rise in proportion to particulate pollution levels. A study by Johns Hopkins and Harvard researchers, jointly funded by EPA and industry, found that the overall death rate in the 90 largest U.S. cities increased by 0.5 percent for every 10 micrograms per cubic meter increase in PM10 measured the day before death. The effect was greater for deaths due to heart or lung disease.
Researchers have found this proportionate rise in the death rate at every level of particulate pollution. They have not found any threshold below which particulate pollution fails to correlate with additional deaths.
These conclusions are particularly worrisome for people accustomed to smelling wood smoke in their neighborhoods during winter. In Seattle, average annual means for PM10 have been in the range of 12-25 micrograms per cubic meter in recent years, with highs in the range of 48-75 micrograms per cubic meter, according to the Washington Department of Ecology. But particulate levels experienced by individuals may run much higher during winter in neighborhoods where wood burning is prevalent.
Wood stoves and fireplaces account for 62% of the Puget Sound region’s fine particle pollution during winter, according to Puget Sound Clean Air Agency. The agency says that this contribution can reach 80% in some neighborhoods. Statewide, wood stoves and fireplaces produce more fine particle pollution than industry and motor vehicles combined.
While staying indoors may help reduce exposure to airborne particulate, the larger part of outdoor concentrations ultimately finds its way inside, even in new houses and even when the doors and windows are closed. PM10 penetrates floors and walls, because the particles are so small. In addition, PM10 tends to remain suspended in the air for long periods of time, rather than settling to the ground, because the particles weigh virtually nothing.
This means that people in smoky neighborhoods may be breathing dangerous levels of particulate at any or all times of day, even inside their homes. Particulate from a neighbor’s wood fire in the evening may continue to penetrate your home all night long and beyond.
The ALA reports that the people most at risk for premature death due to particulate exposure are infants and children, the elderly, people with heart or lung disease, and adults who exercise rigorously.
The effect of wood smoke on infants is well documented. Several studies have found that home use of wood stoves increases the risk of lower respiratory tract infections such as bronchiolitis and pneumonia in young children, according to the Washington Department of Ecology. These types of infections are a major cause of early childhood disease and death. In a 1997 study, EPA found an association between infant mortality and particulate exposure in the first two months of life.
Researchers at the University of Washington have demonstrated measurable reductions in lung function among otherwise healthy children in Seattle neighborhoods where wood smoke is prevalent. Seattle preschool children living in high wood smoke areas have shown more symptoms of respiratory disease than children living in lower wood smoke areas.
Children with asthma are particularly sensitive to particulate pollution such as wood smoke. In a study published in 1999, UW researchers found that increases in PM10 levels in Seattle resulted in increased asthma symptoms among children with mild or moderate asthma. Other studies have associated increases in PM10 levels with increases in emergency room visits for childhood asthma.
In recent years, asthma has become relatively common among children in this region. The ALA estimates that one in 10 children in Washington suffer from asthma.
Wood smoke affects adults as well. Wood smoke is known to aggravate heart and lung disease. The Washington Department of Ecology reports that long-term exposure to wood smoke may lead to emphysema, chronic bronchitis, arteriosclerosis and cancer. EPA research indicates that the lifetime cancer risk from wood smoke is 12 times as great as from an equal volume of cigarette smoke.
The ALA reports that recent laboratory tests of healthy young men and women have detected pulmonary inflammation and blood changes in response to concentrated ambient particles. In addition, increases in PM10 levels in Seattle and other cities are associated with increased hospital admissions for cardiovascular disease, pneumonia, and chronic obstructive pulmonary disease. A Harvard study published in 1999 indicates that air pollution may account for 5% of hospital admissions for heart disease in Seattle and several other cities.
In light of the adverse impact of wood smoke on human health and the environment,
Puget Sound Clean Air Agency recommends replacing fireplaces and wood stoves with gas or propane log inserts. These fuels are approximately twenty thousand times cleaner than burning wood in an older woodstove. Newer gas log models realistically simulate a wood fire.
According to Jim Nolan, Director of Compliance at Puget Sound Clean Air Agency,
"The Board of the Puget Sound Clean Air Agency has urged the staff to develop a long term public information campaign on wood smoke similar to that for cigarette smoke. The point of the campaign is to change the public perception of wood smoke from representing ‘home and hearth’ to the health hazard it presents, particularly for sensitive individuals."
If you are bothered by wood smoke in your neighborhood, contact Puget Sound Clean Air Agency at 206-343-8800 or 1-800-552-3565 (or http://www.pscleanair.org). The agency has authority to impose fines in the thousands of dollars for violations of emission standards for wood smoke.
For more information about the health effects of wood smoke and other airborne pollution, contact the American Lung Association, Washington Chapter at 206-441-5100 (or www.alaw.org).
An organization specializing in education and research about the health effects of wood smoke is Burning Issues (www.burningissues.org.).
Another resource is S.E.N.S.E. (Solutions for Eliminating Neighborhood Smoke Emissions) at P.O. Box 2308, Redmond, WA 98073-2308 or 425-818-7736 email: havesomesense@hotmail.com (website address not yet finalized).
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