Indoor Woodsmoke PM and Asthma

Although particulate matter (PM) exposures have been linked with poor respiratory health outcomes, most of these studies have focused on airsheds with urban and industrial sources of PM2.5. Woodsmoke-derived PM also contributes to ambient PM in these urban areas, and is the major source of PM in many US rural or peri-urban areas, as well as in many communities within developing countries. This study will focus on indoor air quality and clinically relevant changes in health effects among asthmatics living in homes whose primary heating sources are non EPA-certified woodstoves. The Primary Aim of this study is to assess the efficacy of residential interventions to reduce indoor PM exposure from woodstoves and the corresponding improvements in quality of life and health outcomes for asthmatic children. The study area for this project will be three rural communities in western Montana and Idaho, including one Indian Reservation. This study will use a three arm (Tx1, Tx2, and Tx3) randomized placebo-controlled intervention trial. The interventions will be at the household level, and exposure and outcomes will be assessed for one asthmatic child in each household. Households in Tx1 will receive inactive high efficiency particulate air (HEPA) devices and will serve as the placebo group. Households in Tx2 will receive a new EPA-certified woodstove, while households in Tx3 will receive active HEPA devices. The Secondary Aims of this study are to assess the impact of these interventions on residential PM2.5 exposures and other health outcomes. Secondary exposure outcomes measured prior to and following the intervention will include PM2.5 mass, chemical woodsmoke markers on PM2.5 filters (including levoglucosan and abietic acids), and biomarkers of woodsmoke exposure. Secondary asthma-related health outcomes measured prior to and following the intervention will include peak expiratory flow (PEF) and forced expiratory volume in first second (FEV1), biomarkers in exhaled breath condensate, and frequency of asthma symptoms, medication usage, and healthcare utilization. To our knowledge, this will be the first randomized trial in the US to utilize a woodsmoke intervention to assess the impact of the consequent reductions in indoor PM on health outcomes in a susceptible population. The results from this project will be translatable to other regions in the US and the world where biomass burning is commonly used for heating and cooking.