Wildfire Smoke Exposure and Physiological Responses in Subsidized Housing in Metro Vancouver

Indoor environmental quality (IEQ) data from subsidized housing are limited despite growing concern about climate-related hazards such as wildfire smoke and extreme heat. Residents in subsidized housing may face exposure-related risks due to existing health, socioeconomic, and building-related constraints. The Subsidized Housing Multi-Unit Residential Buildings (SHMURB) study collected field data from May 2024 to May 2026 in subsidized housing apartments in Metro Vancouver to characterize IEQ and short-term physiological responses using low-cost sensors, wearable devices, and questionnaires.

Air Quality Egg monitors were deployed in 54 units across three study buildings to continuously measure fine particulate matter (PM2.5), carbon dioxide, temperature, and relative humidity. Physiological data were collected using Fitbit devices, including sleep metrics, heart rate–related measures, and blood oxygen saturation. Questionnaires were administered to characterize unit-level living conditions, occupant behaviors, and pre-existing health conditions. Preliminary analyses were based on the first 21 months of data collection.

We examined temporal dynamics of PM2.5 exposure during a wildfire smoke event. In non-smoking units, as outdoor PM2.5 concentrations increased, contributions shifted from predominantly indoor to outdoor-driven. Indoor concentrations remained lower than outdoors but responded rapidly to outdoor smoke changes, suggesting efficient smoke infiltration into units. In contrast, units with household cigarette smoking maintained elevated indoor concentrations regardless of outdoor conditions.

Sleep metrics showed a consistent physiological response to wildfire smoke. Other health parameters, including heart rate variability, resting heart rate, and blood oxygen saturation, changed among participants with cardiovascular conditions, asthma, or diabetes. Overall, the findings suggest that occupant behaviors, including household smoking, may contribute to differences in indoor exposure patterns during wildfire smoke events. Physiological responses were also observed, particularly among participants with pre-existing conditions. These results highlight the value of combining indoor environmental measurements with personal wearable health monitoring to study climate-related health risks, with elements of a citizen-science approach.