Influence of road proximity on ambient concentrations of organic and elemental carbon fractions in coarse and fine particulate matter

Abstract

Dear Editor, Our research group has recently completed a study characterizing coarse and fine ambient PM and road dust near major roads in the Greater Boston area, with several papers included in a recent specialty issue of this journal (Huang et al. 2020; Martins et al. 2020; Silva et al. 2020). During this study, we investigated 27 roadway locations, selected based on parameters including traffic density and composition, slope and elevation, number of traffic lights nearby, type of structures/buildings present, condition and cleanness of the pavement, number of lanes and traffic directions, the width of the road, posted speed limit, nearby point sources (minimal), and having a safe and convenient place for sampling. At each site, we collected ambient PM and road dust samples at a series of three distances away from the road: <25 meters, 50–200 meters and >500 meters. Most road sites were sampled once, and a subset of seven roads was sampled multiple times (including different seasons). For this study, we developed (1) a mobile unit with ambient particle concentrators to measure hourly concentrations of elements as a function of distance to road, and (2) a road dust sampler to collect size-fractionated road dust particles from the road surface. These methods are described in detail elsewhere (Martins et al. 2020).