Pollutant measurements at near road and urban background sites in New York, USA

Due to the potential for heightened exposure to vehicle exhaust pollutants, air monitoring has been required at near roadway (NR) locations within large urban centers in the United States since 2010. In this paper pollutant measurements at two urban NR locations, Rochester and New York City, Queens are discussed. Pollutants measured at these sites include PM2.5 mass, nitrogen oxides (NO, NO2, NOx), ultrafine particles (UFP), black carbon (BC) and carbon monoxide (CO). Measurements at NR sites are made in conjunction with existing urban background (UB) sites. Although pollutant concentrations at Rochester and Queens are elevated at the NR sites compared to the UB sites particularly during the daytime hours, all pollutants are below the level of the National Ambient Air Quality Standards (NAAQS). At Rochester, BC at the NR site is elevated by a factor of 2–3 between 7 a.m. and 3 p.m. and drops to near uniform concentrations at both sites at night. The enhancement or increment in BC is highest in summer and lowest in winter. Other co-pollutants including NOx and CO are also elevated at the Rochester NR site by varying degrees during daytime hours. Similarly, enhanced pollutant concentrations are observed at the Queens NR site. At both locations small increments are observed for PM2.5 mass. For example, an annual increment of 0.27 μg/m3 and a daily increment of 0.80 μg/m3 was observed at the Rochester NR site. At Queens NR annual PM2.5 mass increments of 0.92 and 1.0 μg/m3 were observed in 2017 and 2018. In addition, a NR daily increment of 1.4 μg/m3 was observed at Queens in 2018. The data are analyzed for diurnal, weekday vs weekend and seasonal patterns. Nonparametric wind regression identified the roadways as the major source of traffic related air pollutants.