Methods and Considerations for Near-Road Air Quality Monitoring

1. Methods and Considerations for Near-Road Air Quality Monitoring Rich Baldauf, U.S. EPA 2008 National Air Quality Conference April 6-9, 2008 Portland, Oregon

2. Overview • Why are we concerned with near road air quality? • What do previous monitoring studies show? • What are the key factors to consider for near-road monitoring?

3. Why are we concerned? • Estimate over 35 million people live within 100 meters of a major transportation system including 4+ lane highways • More than 1,000 compounds have been identified in exhaust and evaporative emissions from mobile sources • Regulated Pollutants • Air Toxics • Particulate Matter • Air quality measurements have indicated elevated pollutant concentrations near roads • CO and Pb the focus during the 70’s • Recent studies indicate complex mixture of pollutants

4. Why are we concerned? • Living near major roadways has been associated with numerous adverse health endpoints • Cardio-respiratory effects (e.g., asthma, bronchitis) • Adverse birth outcomes/developmental effects • Premature mortality • Cardiovascular effects • Childhood cancer • Hundreds of studies published just since 2000 • Account for varying fleets, engine technologies, etc. • Evidence not equally as strong for each of these health effects • Most initial studies conducted in Europe, although similar results have been reported for all parts of the world including the U.S.

5. Key Factors for Consideration • Objectives for near road monitoring • Measurement data needs • Traffic activity • Meteorology • Air Quality • Network Design • Monitor number/placement • Site location(s)

6. Potential Monitoring Objectives • Trends sites to evaluate control strategies and fuel changes • Accountability of regulatory programs • SIP evaluations • Monitoring data to evaluate regulatory emissions and dispersion models used for local assessments • Environmental Impact Assessments (e.g. NEPA) • Inventory projections • Urban and land use planning • Community-scale monitoring • Evaluate concentrations near transportation sources • Support health studies/determine population exposures • Evaluate mitigation measures

7. Measurement Data Needs • Traffic Activity • Key parameters: Volume, fleet mix, speed • Many DOTs collect this data, but require coordination for access • Meteorology • Key parameters: Wind direction, wind speed, temperature, humidity • 3-D measurements can provide added parameters (e.g., standard deviation of the vertical fluctuation in wind – measure of turbulence) • Vehicle induced turbulence may affect siting meteorological stations (horizontal distance from road and vertical height) • Air Quality • Pollutants of interest • NAAQS pollutants: CO, NO/NO2/NOx, Pb, PM10, PM2.5 • Particulate Matter: size, number, carbon, organics, elements, ions • Air Toxics: VOCs (e.g., benzene, 1,3-butadiene), carbonyls (acetaldehyde, formaldehyde, acrolein), etc. • Measurement frequency • Shortest averaging times generally most desirable to determine relationships among traffic, meteorology and air quality

8. CO Traffic, Meteorology and Air Quality Relationships BC Traffic Volume Wind Direction

9. NO Wind Dir. Pollutant Mixtures Traffic Volume CO Ammonia Benzene Naphthalene

10. Near-Road PM Elemental Chemical Characteristics

11. Network Design Considerations • Monitor number/placement • Distance from the road (monitoring objectives) • Upwind/background monitoring • Horizontal/vertical spacing • Site location: • Type of road • Highway • Arterial • Traffic volumes and activities supported • Roadway design • Topography: at-grade, depressed (vertical, sloped), elevated • Roadside structures: noise barriers, vegetation, buildings

12. Concentration Changes with Distance from Road

13. Wind Tunnel Assessments:Roadway Design

14. Wind Tunnel Assessments:Roadway Design

15. Fluid Dynamics Modeling: Noise Barriers and Vegetation

16. Noise Barrier and Vegetation Effects

17. Noise Barrier and Vegetation Effects

18. Summary • Growing interest in collecting near road air quality data • A number of factors should be considered before initiating monitoring • Objectives/needs • Pollutants of interest • Integration with traffic and meteorological data • Network design • Number and distance from road/background sites • Site location • Type of road • Presence of structures, changing topography • Representativeness of site for monitoring objectives

19. Participants Brian Gullett, Cary Secrest, Dave Davies, David Heist, David Olson, David Proffitt, Eben Thoma, Eric Morris, Fu-Lin Chen, Gorge Bowker, Ian Gilmour, Jason Weinstein, John Kinsey, John McGee, Laurie Brixey, Mike Hays, Nealson Watkins, Patricia Rowley, Rich Baldauf, Richard Shores, Richard Snow, Robert Seila, Seung-Hyun Cho, Steve Perry, Sue Kimbrough, Tim Barzyk, Todd Krantz, Tom Long, Vlad Isakov, Andrey Khlystov, Chris Frey, John Bang Organizations: U.S. Environmental Protection Agency • Office of Research and Development, Research Triangle Park, North Carolina, USA • National Risk Management Research Laboratory • National Health and Environmental Effects Research Laboratory • National Exposure Research Laboratory • Office of Air and Radiation • Office of Transportation and Air Quality • Office of Air Quality Planning and Standards • Office of Civil Enforcement National Oceanic & Atmospheric Admin, Atmospheric Sciences Modeling Division Arcadis Inc., Research Triangle Park, North Carolina, USA Alion, Research Triangle Park, North Carolina, USA Duke University, Department of Civil and Environmental Engineering North Carolina Central University, Department of Environmental Sciences North Carolina State University, Department of Civil and Environmental Engineering