  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 403 adults from 230 households in a small urban area in northern Utah, US,
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, and controlled for personal and household characteristics. Our
models found some measurable changes in activity and travel patterns on days
with poor air quality. In urban areas, people engaged in more mandatory
(work/school) activities, whereas there was no discernible change in
suburban/rural areas. 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 traveled shorter total distances (mostly through lower
vehicle miles traveled), and there was a notable uptick in the probability of
being an active mode user (walk/bike). Air quality perceptions also seemed to
play a role, at least for urban residents who walked/biked longer distances,
rode the bus for longer distances/times, and drove fewer miles on days with
worse perceived air pollution. Overall, the results are somewhat encouraging,
finding more evidence of altruistic than risk-averse travel behavioral
responses to episodes of area-wide air pollution; although, more research is
needed.
