The impact of wood smoke on ambient PM 2.5 in northern Rocky Mountain valley communities

Abstract

During the winters of 2006/2007 and 2007/2008, PM 2.5 source apportionment programs were carried out within five western Montana valley communities. Filter samples were analyzed for mass and chemical composition. Information was utilized in a Chemical Mass Balance (CMB) computer model to apportion the sources of PM 2.5. Results showed that wood smoke (likely residential woodstoves) was the major source of PM 2.5 in each of the communities, contributing from 56% to 77% of the measured wintertime PM 2.5. Results of 14C analyses showed that between 44% and 76% of the measured PM 2.5 came from a new carbon (wood smoke) source, confirming the results of the CMB modeling. In summary, the CMB model results, coupled with the 14C results, support that wood smoke is the major contributor to the overall PM 2.5 mass in these rural, northern Rocky Mountain airsheds throughout the winter months.