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Air and Climate Change Research

  Basic Information

Image: 4 lane congested  highway at rush hour
With over 35 million people in the United States living within 300 feet of a major road, there is growing concern about the health impacts from the air pollutants associated with the cars, trucks and other vehicles on them.


In recent years, a large number of health studies have identified increased risks of adverse health effects for populations spending significant time near major roads. Studies have shown that people who live, work, or attend school near major roads have an increased incidence and severity of particular health problems that may be related to air pollution from roadway traffic. Health effects include reduced lung function and impaired development in children, asthma, cardiovascular disease, low birth weight, and pre-term newborns, and premature death. Emission inventories reveal that mobile sources significantly contribute to local and national concentrations of a number of air pollutants.  Air quality monitoring studies have measured elevated concentrations of pollutants emitted directly by motor vehicles near large roadways, adding to the public health concern for adverse health effects resulting from exposures to motor vehicle emissions.

Regulatory Impacts and Benefits

  • Support the Integrated Science Assessments (ISAs) for NAAQS reviews of NO2, PM, Pb, and CO
  • Provide the methods and measurements information needed to implement near-road monitoring networks as part of the NO2 NAAQS revision (and likely future revisions for other pollutants)
  • Identify the need for and benefits of more stringent motor vehicle emissions standards
  • Key component of the public health case for the 2007 Mobile Source Air Toxics Rule
  • Support regulatory decisions requiring the U.S. DOT to ensure that new highway and transit projects in will not adversely impact attainment of air quality standards (Conformity Rule)
  • Support need and methods for state DOTs to account for near-road air quality impacts from new and modified transportation facilities as part of NEPA assessments
  • Provide urban and transportation planning communities with mitigation options related to land use, roadway design, and roadside barriers
  • Provide the tools needed to conduct local-scale modeling for regulatory (Conformity, NEPA, NAAQS SIPs, health and benefits assessments) and research evaluations of near-road air quality and exposures

Scientific Questions

Research is needed to better understand what type of pollutants are common near roadways, how people are exposed to them, the extent of exposure, and the type and severity of health effects. The key scientific questions that we are seeking to answer are:

  • How do traffic and roadway emissions affect exposures and adverse health effects for populations living, working, or going to school near roads?
  • What decision tools are available, or can be produced, to identify the relationship from traffic emissions to population exposures and to adverse health effects for use in regulatory decision-making and transportation planning?
  • Do public facilities located near major roadways present an exposure and health risk to their occupants?
  • How do motor vehicle emissions affect near-road air quality and human exposures that may ultimately lead to adverse human health effects?
  • What is the spatial and temporal variability of traffic-related pollutants near roadways?
  • How do traffic (volumes, speeds, fleet mix, etc.) and environmental (meteorology, topography, etc.) conditions affect emissions and near-road air quality?
  • What marker(s)/metric(s) can be used to identify exposures to traffic-related emissions?
  • What tools are available, or can be produced, to identify the relationship from traffic emissions to population exposures to adverse health effects for use in regulatory decision making and transportation planning?
  • How does urban design and the presence of roadside features impact near-road air quality?
  • Are there mitigation techniques that can reduce exposures to traffic emissions for impacted populations?

What We Are Doing about It!

We have launched a series of near-roadway studies as part of an integrated and multi-disciplinary. Our research objectives are to:

  • Identify and define mobile source emissions through direct measurements of vehicles and monitoring near roads with varied traffic levels and vehicle classifications
  • An understanding of the complex mixture of gaseous and PM pollutants near roads that enlightens health professionals on potential causes of reported adverse health effects for near-road populations. 
  • 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 to include the development and improvement of models for use in regulatory and research applications.
    • Emissions models (MOBILE/MOVES)
    • Air quality models (AERMOD, CMAQ)
    • Risk and health assessments
  • Assess the health effects from near-roadway exposures
  • Work with US EPA Office of Air and Radiation and identification of the need and benefits of new regulatory or voluntary motor vehicle emission control programs to protect public health and welfare
    • New emission standards (e.g. MSAT Rule)
    • Clean diesel programs
  • Urban planning considerations (e.g. transit and VMT reduction)
  • Detailed chemical and physical data on ambient VOC and PM size-fractionated concentrations for SOA and source apportionment assessments
  • Identification of the need and benefits of new NAAQS (e.g. NO2, CO, PM, and Pb)
  • Guidance for near-road monitoring network design to support NAAQS reviews

Following the completion of a pilot study in Raleigh, NC, the first full-scale study to measure, define, and profile roadway air pollutants began in December 2008 along a portion of I-15 in Las Vegas. During the year-long study, EPA scientists and engineers will work with the Federal Highway Administration to gather information to better understand the relationship between traffic emissions and roadway-related air pollution concentrations at various distances from the roadway.

Air and Climate Change Research | Water Research | Ecosystems Restoration Research | Land Research | Technology: Sustainable Technologies Research, Environmental Technology Verification Program (ETV), and Technology Assessments

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