Outdoor wood furnaces create significant indoor particulate pollution in neighboring homes

<i>Context</i>: The use of outdoor wood furnaces (OWFs) is common in many parts of the United States. Little published information exists on the concentrations of outdoor and indoor fine particulates found near OWFs.<i>Objective</i>: To compare PM_2.5 (cts) and PM_0.5 (cts) particle concentrations inside four Connecticut homes located 30.5–259 m from OWFs, and inside six Connecticut control homes located more than 2 km from the nearest OWF.<i>Materials and methods</i>: PM_2.5 (cts) and PM_0.5 (cts) measurements were made with a Dylos light-scattering particulate counter.<i>Results</i>: Mean PM_2.5 (cts) concentrations were 4.21 times as great in the four OWF exposed homes than the six control homes (0.302 × 10⁶ counts/m³ versus 0.0718 counts × 10⁶/m³<i>p</i> 2.5 (cts) concentrations inside the four OWF exposed homes roughly corresponds to a mass PM_2.5 of 37 µg/m³, which is above the US EPA 24-h PM_2.5 limit of 35 µg/m³. Mean PM_0.5 (cts) concentrations were 3.44 times as great in the four OWF exposed homes than in the six control homes (0.657 versus 0.191 × 10⁶/m³<i>p</i> 2.5 (cts) and PM_0.5 (cts) concentrations were significantly higher in the house 259 m from an OWF as compared with the mean of the six control homes.<i>Conclusion</i>: Existing regulations, such as the present Connecticut law requiring a 61 meter distance between an OWF and neighboring homes, are not adequate to protect the health of neighboring residents.