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Air Research

Near Roadway Research


With more than 35 million people in the United States living within 300 feet of a major road, there is growing concern about the potential health impacts from the air pollutants associated with the cars, trucks and other vehicles.
Studies have shown that people who live, work, or attend school near major roads have an increased incidence and severity of health problems that may be related to air pollution from roadway traffic. Health effects linked to near roadway exposures include reduced lung function and impaired lung development in children, asthma, cardiovascular disease, low birth weight, pre-term newborns, and premature death.

Additional research is needed to learn more about pollutants near roadways, how and to what extent people are exposed to them, and the type and severity of associated health effects.

Near Road Air Pollution Studies

A series of multidisciplinary studies on air pollution near roads is producing important scientific data and tools for federal, state and local governments and organizations to make decisions about future road projects and to address health concerns related to roadways.

The research will be used in the development of federal regulatory and voluntary programs at the community and local government level to reduce air pollution along highways. State highway and environmental agencies can use the science to assess the local health impacts of transportation decisions.

The information also can assist local school districts with decisions on whether to locate new schools near large roadways, and how to mitigate impacts from local roads on existing schools.

With data collected from the roadway studies, numerous scientific papers, models and assessment tools, and synthesis products will be prepared that will improve knowledge about the impacts of traffic emissions on air quality near roads and the possible links to adverse health effects.

Photo of cars on a highway

The research objectives are to:

  • Identify and define mobile source and roadway emissions through direct measurements of vehicles and monitoring near roads with varied traffic levels and vehicle classifications
  • Assess factors affecting the variability of near-road air pollutants, such as traffic activity and roadway-design features
  • Improve modeling tools for near-road air quality and human exposure assessments
  • Assess the health effects from near-roadway exposures

Key scientific questions include:

  • How do traffic and roadway emissions affect exposures and adverse health effects for populations living, working, or going to school near roads?
  • What kinds of air pollution have negative effects on human health?
  • What decision tools are available or can be produced that can be used in regulatory decision-making as well as transportation and community planning?
  • Do public facilities located near major roadways present an exposure and health risk to their occupants?


Dan Costa (costa.dan@epa.gov), interim National Program Director, Air, Climate and Energy Research Program, EPA's Office of Research and Development, 919-541-2532.

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Past Research

To explore how traffic emissions may lead to adverse health effects for people living, working, or attending school near large roads, EPA researchers began work in the early 2000s to study air pollution near highways. Activities included:

  • Measurements of traffic and air quality near existing roads
  • Physical modeling of different road designs using wind tunnel
  • Computer modeling
  • Toxicology research

Brooklyn Study
In 2004, EPA conducted the Traffic-Related Exposure (T-REX) study to assess the impacts of traffic emissions on air pollutants present near highways and in urban street canyons along these roads. The study, conducted in Brooklyn, N.Y., also focused on how these pollutants infiltrated into a nearby row-house.

The results led to the development of a more broad-based pilot 2006 EPA research project, conducted in Raleigh, N.C., to assess technical sampling approaches to assess the relationship between traffic activity, meteorology and air pollutant concentrations for a wide variety of traffic-emitted pollutants.

Results of the Raleigh study highlighted the presence of elevated concentrations of a complex mixture of pollutants near roadways, the influence of traffic and meteorology on these concentrations, distance from road, and the potential role of natural and man-made features near roads in mitigating air pollutant levels. Using this information, wind tunnel modeling assessments were conducted to identify how the presence of these features, or changes in the road design and topography, influenced near-road air pollutant concentrations.

These collective field and wind tunnel assessments have led to improvements in computer models used to predict air quality in urban areas. The Raleigh pilot study also yielded toxicological data.

Las Vegas Study
A year-long study in Las Vegas was conducted with the Federal Highway Administration in December 2008. The study helped to improve understanding of the relationship between traffic-related emissions and roadway-related air pollution concentrations at various distances from the roadway.

Questions asked included:

  • How do traffic emissions affect near-road air quality?
  • What type and amounts of pollutants are common near roadways?
  • What are the controlling factors that determine the nature of exposure to people?

Researchers gathered data on traffic counts, vehicle types, roadway characteristics and meteorological conditions (including wind speed and direction, temperature, and humidity). Measuring instruments were placed 10, 100, and 300 meters east of I-15 near West Post Road and 100 meters west of I-15 near Dean Martin Drive.

EPA scientists also conducted studies using mobile air quality monitoring and wind tunnel assessments to determine how the design of roadways and the presence of roadside structures influence near-road air quality concentrations.

The results of these research projects will allow EPA to identify the most effective strategies and tools to control traffic emission impacts on exposures and adverse health effects from roadway air pollution. Strategies and tools for reducing adverse effects may include reducing vehicle emissions and placing man-made and natural barriers (including vegetation and variations in topography) near roadways to protect those who live, work or attend school nearby.

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Current Research

EPA scientists are currently working in Detroit with the local Department of transportation, community leaders, and researchers at the University of Michigan to examine the link between roadway-related pollution and human health. The study is called the Near-Road Exposure to Urban Air Pollutants Study (or NEXUS).

The goal of this comprehensive study is to understand the associations between sources of air pollutants, human exposure and health outcomes in a single location and study. The study tracks pollution by source, and follows it through the local environment. Scientists are examining the chemical profiles of select mobile source air toxics associated roadway pollution, the size and behavior of roadway-related particles, and the effects these substances have on health in susceptible groups.

Researchers are working with the families of children suffering from asthma in the Detroit area as part of the study to learn about the relationship between air pollution conditions and asthma symptoms.

EPA and University of Michigan scientists are working closely with community based groups, including Community Action Against Asthma (CAAA), to keep survey participants informed of the latest developments in the project, as well as to help them find health care for their children with asthma.

Researchers anticipate that the results of NEXUS will provide communities, civic leaders, and regulatory bodies with a better understanding of how highway-related pollution can impact the health of the people living near major roads. With this information, policymakers will be able to make better-informed decisions about urban development that will help protect the health of their communities.

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As the near-roadway studies are completed, journal articles are providing new insights and findings about the relationship between air pollution near highways and health effects. Selected articles published in scientific journals are provided below.

Cho, S.-H., Tong, H., McGee, J.K., Baldauf, R.W., Krantz, Q.T. & Gilmour, M.I. Comparative toxicity of size-fractionated airborne particulate matter collected at different distances from an urban highway. Environ Health Perspect: doi:10.1289/ehp.0900730. [Online 29 June 2009]

Baldauf, R.W., N. Watkins, D. Heist, C. Bailey, P. Rowley, R. Shores. 2009. Near-Road Air Quality Monitoring: Factors Affecting Network Design and Interpretation of Data, J. of Air Quality, Atmosphere, & Health. Vol. 2: 1-9.

Venkatram, A, V. Isakov*, R. Seila, R.W. Baldauf. 2009. Modeling the Impacts of Traffic Emissions on Air Toxics Concentrations Near Roadways, Atmospheric Environment 43: 31913199.

Baldauf, R.W., A. Khlystov, V. Isakov, E. Thoma, G.E. Bowker, T. Long, R. Snow. 2008, Impacts of Noise Barriers on Near-Road Air Quality, Atmospheric Environment. 42: 75027507

Baldauf, R.W., E. Thoma, M. Hays, R. Shores, J. Kinsey, B. Gullett, S. Kimbrough, V. Isakov, T. Long, R. Snow, A. Khlystov, J. Weinstein, F. Chen, R. Seila, D. Olson, M.I. Gilmour, S.H. Cho, N. Watkins, P. Rowley, J. Bang. 2008. Traffic and Meteorological Impacts on Near Road Air Quality: Summary of Methods and Trends from the Raleigh Near Road Study, J. Air & Waste Manage Assoc. 58:865878

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