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

TL;DR

This study investigates how air quality influences travel and activity behaviors in northern Utah, revealing that poor air days lead to increased public transit use in urban areas and more active travel in suburban/rural areas.

Contribution

It provides new empirical evidence on the differential impacts of air pollution on travel behavior across urban and suburban/rural neighborhoods using detailed survey data.

Findings

Urban residents increase public transit and work activities during poor air quality days.

Suburban/rural residents tend to travel shorter distances and walk or bike more.

Perceived air quality influences individual travel mode choices and distances.

Abstract

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.