Exploring the Impacts of Air Quality on Travel Behavior and Activity Participation: Evidence from Travel Diary Surveys in Northern Utah

In this study, we explored whether and how area-wide air pollution affected individuals’ activity participation and travel behaviors, and how these effects differed by neighborhood context. Using multi-day travel survey data provided by 390 adults from 223 households in a small urban area in northern Utah, United States, we analyzed a series of 20 activity and travel outcomes. We investigated the associations of three different metrics of (measured and perceived) air quality with these outcomes, separately for residents of urban and suburban/rural neighborhoods, while weighting and controlling for personal/household characteristics and weather. Our regression models detected measurable changes in activity and travel patterns on days with poor air quality. People engaged in more mandatory (work/school) and fewer discretionary activities. The total travel time for urban residents increased, driven by increases in trip-making and travel time by public modes (bus) and increases in travel time by private modes (car). On the other hand, suburban/rural residents exhibited behavior consistent with mode shifts from driving to active transportation, such as: less car travel (distance and time), longer transit distances, more walking/bicycling (trips, distances, and time), and greater odds of being an active mode user. Air quality perceptions also seemed to play a role, with some evidence for increased active transportation and public transit usage on days with worse perceived air pollution. Overall, the results offer more evidence of altruistic than risk-averse travel behavioral responses to episodes of area-wide air pollution, although more research is needed.