Smoke: Emissions and Noncancer Respiratory Effects

During the past twenty years, the use of wood has become popular as an alternative to conventional home heating fuels. Part of this movement has been due to uncertainty about the availability of fossil fuels. About ten percent of space heating in urbanized areas of the northern United States is from wood burning, with up to fifty percent in some .smaller, rural towns (42, 63, 75, 85). Wood is obviously a renewable resource. This attraction is offset, however, by the increased air pollution emissions from wood heating devices compared with devices fueled with oil or gas. As noted initially by Cooper (20), particle and organic carbon emission rates can as much as one to two orders of magnitude larger in wood heating devices than in oil or gas heating units. Legislation restricting the sale of conventional wood stoves first appeared in Oregon in 1984, followed by nationwide restrictions in 1988. Although rapid progress has reduced emissions in some types of modern wood heaters, older "conventional" wood stoves and fireplace inserts are still the predominant appliance in use today. As discussed later in this document, a number of communities continue to experience elevated levels of wood smoke during the winter heating season. In addition, elevated indoor air pollution levels have been observed in homes with non-airtight or improperly operated wood stoves. As a result, there has been an ongoing interest in the potential health effects of exposure to wood smoke. Several reviews of the health effects of wood smoke have been