This action will remove the existing network design requirement to install near-road NO2 monitoring stations in Core Based Statistical Areas (CBSAs) having populations between 500,000 and 1,000,000 persons, due by January 1, 2017. The EPA is finalizing this action based on a review of research data and routine NO2 monitor data generated by existing near-road NO2 sites that were established in larger CBSAs beginning in 2012. The data from these near-road NO2 sites, the majority of which are located in higher populated CBSAs having 1,000,000 or more persons, indicate that the current NO2 air quality concentrations in the near-road environment are generally well below both the annual and 1-hour daily maximum NAAQS levels of 53 ppb and 100 ppb, respectively. Due to the correspondence between population, traffic, and expected NO2 concentrations in the near-road environment, it is anticipated that measured near-road NO2 concentrations in relatively smaller CBSAs (e.g., CBSAs with populations less than 1,000,000 persons) would typically exhibit similar, if not lower, concentrations than what is being seen in larger urban areas. Therefore, this action will reduce additional burden on state and local air monitoring agencies by removing monitoring requirements in locations where measured NO2 air quality is expected to be well below the NAAQS. This action does not address the existing requirements for near-road NO2 monitoring in CBSAs having 1,000,000 or more persons.