By Christine Kendrick
The urban environment offers a diverse network of transportation options. This network connects us to the things we need every day and is made possible because of high urban density. Residential, recreational, commercial, and employment destinations are located in close proximity to each other and near various transportation options. However, this high concentration of transportation has a down side as transportation is a significant source of air pollution.
Urban arterial roadways have specific characteristics that make them an important target for improving air quality and public health. These major roadways tend to have elevated traffic volumes, including freight, similar to levels seen on highways. However, unlike highways, a large number of people spend time on or along the roadway, walking, bicycling, or waiting for public transit. This proximity creates the potential for increased exposures to traffic-related pollution.
Traffic signals can be another issue. While essential for safety, they can lead to traffic patterns that negatively affect air quality during peak hours due to increased stop and go traffic. Therefore it’s important to target these areas to learn if traffic signals can be optimized to reduce emissions while still balancing other needs such as travel times and safety.
As part of a collaboration with the City of Portland, Portland Bureau of Transportation and Portland State University, I have helped establish an air quality monitoring station along a major road in Portland, OR. Our research collaboration is using the station to learn how changes in transportation patterns affect roadside air quality. Monitoring is essential to understanding the patterns of air pollutants and human health risk. The monitoring station is measuring nitrogen oxides, particulate matter, and meteorology 24 hours a day and there is also continuous measurements of traffic volumes, traffic congestion and traffic signal timing.
It is unique to have detailed air quality data for an urban roadside environment and even more unique to have a corresponding traffic data set. Data from this project complements the near roadway monitoring that the EPA has added, primarily around highways, over the past three years.
Our research collaboration is currently using the data we collect to better understand how the time of day, season, and other conditions combine to create the highest and lowest exposure concentrations for an urban resident. We are using the unique data set to evaluate typical methods used in exposure assessment of intersections, identifying when traffic volumes alone can be used to predict roadside air quality and when it is important to account for meteorological conditions.
Results of our work have been published in Atmospheric Environment, in the paper “Diurnal and seasonal variations of NO, NO2, and PM2.5 mass as a function of traffic volumes alongside an urban arterial” (subscription required).
It is important for us to understand how transportation impacts human health in the urban environment. This work, which involves research that spans the disciplines of atmospheric science and transportation engineering, would not have been possible without the support of EPA’s Science to Achieve Results fellowship program.
About the Author:
Christine Kendrick is a Ph.D. Candidate at Portland State University and a 2012 EPA STAR Fellow. She is currently working with the Portland Bureau of Transportation exploring the potential for expanded monitoring networks to improve our understanding of spatial patterns of urban air quality.
Kendrick, C.M., Koonce, P., and George, L. A. (2015). Diurnal and seasonal variations of NO, NO2, and PM2.5 mass as a function of traffic volumes alongside an urban arterial. Atmospheric Environment 122, 133-141.
Urban Arterials: At the Heart of Public Health and Transportation
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