The State of Nevada Department of Transportation (NDOT) sought to examine and understand the impact of near-road air pollution at a school before and after a freeway widening project in Las Vegas, Nevada. STI planned and performed a multi-million dollar study of mobile source air toxic (MSAT) exposure at three schools along US 95 in Las Vegas. As part of this study, STI measured MSATs and other pollutants outdoors and indoors at three schools and at a nearby background site before and after the freeway was expanded and before and after new filtration systems were installed in the schools. STI also estimated the relative contributions of US 95 traffic to the measured MSAT concentrations. The sampling program also included measurements of near-road variations in CO2 concentrations.
The results of this work benefited stakeholders by:
  • Demonstrating how minor upgrades in particulate filters can greatly improve indoor air quality in schools with respect to diesel particulate matter (DPM)
  • Examining how children who attend schools near major freeways could be exposed to black carbon concentrations twice as high as those concentrations to which children who attend schools in an urban area without freeway proximity are exposed
  • Showing that changes in large-vehicle traffic between 2007 and 2008 on US 95 and throughout the Las Vegas area directly impacted black carbon concentrations at near-roadway schools