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FHWA and EPA National Near-Road Study - Detroit: Executive Summary

Part VI: Summary

This report provides a summary of a field study conducted in Detroit, MI from September 29, 2010 thru June 20, 2011. The objective of this research study has been to determine MSAT concentrations and variations in concentrations as a function of distance from the highway and to establish relationships between MSAT concentrations as related to highway traffic flows including traffic count, vehicle types and speeds, meteorological conditions such as wind speed and wind direction; and other pollutants primarily emitted from motor vehicles such as CO, NO, NO₂, NO_X, BC, PM₁₀, PM_2.5, PM Coarse, and MSATs. These detailed results support the following preliminary conclusions:

• Concentration gradients are observed for gaseous pollutants and black carbon associated with distance from roadway.
• Effect of wind speed appears to be a factor with regards to concentration gradient (e.g., dilution effect).
• Non I-96 sources may be larger contributors than previously expected (Figure 8 and Figure 9), for example:
  • Impact of near-by apartment complex at 300 meter downwind site (e.g., cold-start CO emissions).
  • Telegraph Road (300 meter downwind site).

Preliminary results of this study provide indications that highway vehicle emissions impact near-road air quality. Known highway vehicle pollutants such as CO, NO, NO2, NOX and BC have elevated concentrations in a near-road environment and decrease as one moves away from the road. Additional analysis of the data is needed to more accurately quantify the effect of wind speed as well as other near-road effects.