Exhausting all avenues: why impacts of air pollution should be part of road ecology

Roads are an omnipresent feature of the contemporary landscape and are associated with extensive ecological impacts, including habitat degradation, changes in animal behavior, and increases in wildlife mortality. Road ecology has grown into a dynamic multidisciplinary research area within the environmental sciences, aiming to avoid, minimize, and offset the impacts of road use. However, current best practices in mitigation are often incomplete, failing to account for the full suite of environmental problems that roads create and for the causal mechanisms of those problems. We highlight one environmental problem that is largely absent from the road ecology literature – air pollution from motorized vehicles and from road use. Using recent examples, we discuss our current understanding of the ecological effects of air pollution and describe ways to incorporate it into a comprehensive road ecology research framework. Failure to develop such a framework will result in an incomplete representation of the impact that roads have, and will likely diminish the effectiveness of mitigation strategies.