Characterizing Nitrogen Oxides and Fine Particulate Matter near Major Highways in the United States Using the National Near-Road Monitoring Network

Abstract

As part of the United States Environmental Protection Agency’s 2010 Nitrogen Dioxide (NO2) National Ambient Air Quality Standards (NAAQS) review, a national network of near-road sites was established to characterize pollutant behavior, interaction, and dispersion in the ambient near-road environment. Using spatial interpolation to estimate the near-road concentration increments of NO2 and particulate matter with an aerodynamic diameter of 2.5 μm and less (PM2.5) relative to nearby non-near-road monitors, we found that the 2013–2018 national average increment is 6.9 ppb and 1.0 μg m–3 for NO2 and PM2.5, respectively. Analyses of the hourly near-road NO2, nitric oxide (NO), and PM2.5 increments showed distinct diurnal cycles; the NO2 increment peaks at ∼9 ppb during the early afternoon (2–4 pm local time) while the NO and PM2.5 increments peak during the morning rush hour (5–8 am local time) at 25 ppb and 1.8 μg m–3 for NO and PM2.5, respectively. Although long-term trends are not yet available for this network of sites, a similar analysis of the NO2 and PM2.5 increment at a quasi-near-road site outside of the official network in Elizabeth, NJ showed gradual decreases in the increment over time since the mid-2000s.

Ambient Hydrocarbon Detection with an Ultra-Low-Loss Cavity Raman Analyzer

“…Near roadways, nitric oxide concentrations can reach concentrations well in excess of 10 ppb. 44 Nitric oxide is also a chemical messenger in the human body. It is normally found in breath at concentrations near 200 ppb, and NO deficiencies have been linked to a variety of diseases.…”

“…Diesel vehicles in particular generate significant amounts of nitric oxide. Near roadways, nitric oxide concentrations can reach concentrations well in excess of 10 ppb . Nitric oxide is also a chemical messenger in the human body.…”

The Los Angeles 100% Renewable Energy Study (LA100): Chapter 9. Air Quality and Public Health

“…Communities Near Roads Recent modeling and monitoring analysis have shown that near-road concentration of PM2.5 could be higher than the nearby non-near road or background monitors by about 1 µg/m 3 (DeWinter et al 2018;Craig et al 2020;Gantt, Owen, and Watkins 2021). Some recent studies have shown that electrification will benefit environmentally disadvantaged communities.…”

Chemically specific sampling bias: the ratio of PM2.5 to surface AOD on average and peak days in the U.S.

“…The Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua and Terra satellites measures AOD and has nominal overpass times on a sun-synchronous near-polar orbit of 10:30 a.m. (descending) and 1:30 p.m. (ascending) local time, 25,26 which does not correspond to peak concentrations. 27,28 During six weeks of direct surface measurements during the Southern Oxidant and Aerosol Study (SOAS), 29 hourly ALW mass concentrations and particle hygroscopicity peak at approximately 8 a.m. Throughout the CONUS, peak values in ALW and nitrate mass are perceived to occur on cloudy days 22,30 when remotely sensed AOD is least reliable.…”