Source apportionment studies focused on wood smoke in the northern rockies and fairbanks, Alaska

Elevated PM_2.5 concentrations are more often thought to be associated with highly urban, industrial airsheds such as southern California or areas in the Midwest/east coast of the US. However, due to the prevalent use of wood stoves and the frequency of temperature inversions that occur throughout the winter months, many rural northern Rocky Mountain and central Alaska valley communities also have ambient PM_2.5 concentrations comparable to those found in more urban areas. The results of research programs conducted in five western Montana valley communities (2006/2007 and 2007/2008) and four sites within Fairbanks (2008/2009, 2009/2010, and 2010/2011) revealed that wood smoke (likely residential wood combustion) was the major source of PM_2.5 throughout the winter months, contributing between 56% and ∼80% of the measured PM_2.5. In many rural areas of the continental US and Alaska, there are limited alternatives to burning wood for home heating due to the lack of existing natural gas pipelines and the elevated costs of heating oil and other fossil fuels. Wood burning also has cultural and traditional relevance in many Native and rural areas. From a regulatory standpoint, it will be difficult to lower the emissions from the residential wood stoves. For many, these old polluting wood stoves are the sole source of heat for the individual residences throughout the long winters. Wood stove changeouts (removing old, polluting wood stoves and replacing with EPA-certified, low emission stoves) such as the one conducted in Libby, Montana (where 1,200 stoves were changed out) have shown that large intervention efforts can be effective in reducing ambient levels of wood smoke-related PM_2.5.²² However, without significant financial support, these changeouts can be burdensome for the residents. Perhaps a different strategy could be to focus on trying to further understand the health effects resulting from acute and chronic residential wood smoke exposures. If the resultant health effects of these wood smoke particles are not as harmful as more urban exposures (i.e. diesel and industrial PM_2.5 emissions), one strategy could be to have revised or relaxed standards in these predominantly biomass smoke-impacted communities. Regardless, the findings from these studies suggest that residential wood stoves are a major source of PM_2.5 within these rural valley communities in the Northern Rocky Mountains and inland Alaska throughout the cold winter months.