Volatile Organic Compound Composition and Emissions in a Residential Attic

Volatile organic compounds (VOCs) are important constituents of indoor and urban air pollution. Emissions into building attics have rarely been studied, resulting in a lack of information about this potentially important air pollution source. VOC transport from residential attics to outdoor air is generally missing from emission inventories. In this study, attic VOC concentrations and emissions were assessed in a normally-occupied single-family residence in Oakland, California over 10 weeks during autumn 2021. A proton-transfer-reaction time-of-flight mass spectrometer was utilized to sequentially measure VOC concentrations in the attic, the living space, and outdoors at a rate of twice per hour. Over 200 VOCs were detected at concentrations averaging above five parts per trillion, including many known to be emitted from building materials and wood decomposition. Inert tracer gases were continuously released at known rates into the attic, living zone, and basement to characterize air change rates and interzonal flows. Combining the measurements in a material-balance model, we determine time-resolved and speciated VOC emission factors into the attic and to outdoors from the attic. We find that furfural is a key indicator species and that large diurnal temperature changes in the attic significantly influence VOC emissions from the attic to outdoors.

Information regarding residential attic VOC composition and emission rates is scarce. This study reports average concentrations and investigates the temperature dependence of direct attic VOC emission rates.