Source apportionment of indoor and outdoor volatile organic compounds at homes in Edmonton, Canada

• Indoor and outdoor sources of VOCs were studied in residential homes.
• Higher indoor concentrations were observed than outdoors in both seasons.
• More than 70% of total indoor VOCs were attributed to different indoor sources.
• Industrial and traffic emissions were identified as dominant outdoor VOC sources.

The objective of this analysis was to get a better understanding of emission sources of volatile organic compounds (VOCs) and their contributions to indoor and outdoor concentrations in residences of Edmonton, Alberta. Seven consecutive 24-h indoor and outdoor air samples were collected using Summa canisters in 50 non-smoking homes in both winter and summer of 2010, with 26 homes participating in both seasons. In addition, data were also collected on housing characteristics and occupants’ daily activities. A total of 193 polar and non-polar VOC species were analyzed by gas chromatograph – mass spectrometry (GC–MS). In general, indoor VOC species were found to be substantially higher than outdoor levels during both seasons. A source receptor model positive matrix factorization (PMF) was applied to identify VOC emission sources and apportion airborne concentrations into 13 indoor factors and 10 outdoor factors. More than 70% of total indoor VOCs were attributed to different indoor sources within the residences, where household products were the major contributor (44%, 648 μg/m3), followed by combustion processes and environmental tobacco smoke (ETS) (10.5%, 153 μg/m3), deodorizers (8.4%, 122 μg/m3) and off-gassing of building materials (5.9%, 86 μg/m3). Major outdoor VOC sources included oil and gas industry, traffic emissions, background and biogenic emissions. The findings provide key information about the impact of indoor and outdoor sources on VOC levels in Edmonton homes, which can be useful for developing appropriate risk management measures to improve indoor air quality.