New monitoring regulations require states to establish and operate nitrogen dioxide (NO2) and other pollutant monitors near highly-trafficked roads in major urban areas. STI worked with the EPA on a pilot study to help states identify candidate near-road NO2 monitoring sites that would satisfy monitoring requirements. Data, methods, lessons learned, and experience gathered during the pilot study helped the EPA and states plan full system deployment. In addition, STI helped the EPA prepare its national Near-Road NO2 Monitoring Technical Assistance Document (TAD). The TAD provides in-depth near-road monitoring technical support.