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Recommendations for Designing Roadside Vegetation Barriers to Improve Local, Near-Road Air Quality: Considerations for Right-of-way and Community Planning
Citation:
Baldauf, R. Recommendations for Designing Roadside Vegetation Barriers to Improve Local, Near-Road Air Quality: Considerations for Right-of-way and Community Planning. Presented at TRB Summer Workshop, Washington, DC, July 14 - 16, 2019.
Impact/Purpose:
Numerous health studies indicate that populations spending significant time near major roads face increased adverse health effects. Roadside vegetation has the potential to mitigate these air pollution impacts. EPA developed recommendations for the design and implementation of roadside vegetation as an air pollution mitigation strategy. This information will be useful for urban planners, community leaders and health professionals in implementing sustainable urban designs
Description:
Numerous studies have linked exposure to traffic-emitted air pollution with increased risk for many adverse health effects including asthma, cardiovascular disease, cancer, premature mortality, birth and developmental defects, and even autism. Air quality measurements indicate that air pollution levels can be significantly higher near large roads, with some pollutants like particulate matter and carbon monoxide as much as an order of magnitude higher within the first 100 to 200 meters compared with urban concentration levels. Although this is a relatively short distance, millions of people throughout the world live, work or attend school within this distance. In the United States, over 50 million people are estimated to live within 100 meters of a major transportation facility, the vast majority of these being large-volume highways. In addition, 1 in 11 schools are located within 150 meters of a large highway, including 1 in 5 new schools, exposing over 4 million children daily to traffic emissions. The large number of people exposed to traffic-emitted air pollution, which has been shown to increase adverse health effects, has raised the demand for methods to mitigate these local air quality concerns. While traditional air pollution mitigation strategies, like vehicle emission standards and vehicle activity reduction programs (e.g. transit, congestion pricing, walking and biking options), have been shown to be effective, these techniques can take a long time and expense to implement. In addition, growing vehicle activity often offsets the benefits of these traditional mitigation strategies. As a result, alternative methods of mitigating local air quality concerns are needed to complement the traditional methods. The use of roadside vegetation has received increased attention in recent years as a potential tool to improve local air quality while providing other benefits like flood control, water quality improvement and heat mitigation. Air quality measurement studies have shown that roadside vegetation can reduce concentrations of some air pollutants by 50 percent or more. However, other measurement studies suggest that roadside vegetation provides no air quality benefit or even deteriorates local air quality. This presentation will summarize vegetation characteristics that have been shown to improve air quality downwind of a road, as well as conditions that can exacerbate existing air pollution from traffic. The presentation will also provide resources that can be used to help urban planners, landscape designers, and transportation managers in the design and maintenance of roadside vegetation that can lead to air quality benefits for nearby populations