Consideration of exposure to traffic-related air pollution in bicycle route planning

Introduction: Active transportation modes such as bicycling are key elements of sustainable transportation. In order to promote bicycling as an alternative form of transportation, a holistic approach to improving the quality of the biking experience is needed. The planning of bicycle routes typically takes into consideration available right-of-way, existing roadway infrastructure, and safety concerns, among other factors. Exposure to traffic-related air pollution, on the other hand, is rarely considered despite bicyclists being vulnerable to the harmful air pollution due to their direct exposure to vehicular exhaust and increased breathing rate during biking. Methods: This paper presents a method for incorporating exposure to traffic-related air pollution as another consideration in the bicycle route planning process. The method first applies a streamlined process for estimating the level of near-road air pollution concentration. Then a bicycle route planning tool is developed which allows planners and engineers to compare the exposure of bicyclists to traffic-related air pollution among different bicycle route options. Additionally, this paper demonstrates how to apply the method in two case studies in the City of Riverside, California. Results: Through the case studies, it is shown that considering exposure to traffic-related air pollution can change the results of bicycle mute planning. Conclusions: The presented case studies illustrate how the consideration of exposure to traffic-related air pollution could impact the results of bicycle mute planning. Planners may refer to the presented method or use the information in the analysis differently based on their needs in specific projects. Planners and stakeholders may jointly determine how important the different factors, including exposure to traffic-related air pollution, are in relation to one another and what tradeoff between different factors will be.