Disentangling Impacts of Multiple Nitrogen Dioxide Sources in an Urban Industrial Area

摘要

Air pollution monitoring campaigns support policy development and health effects research. To our knowledge, however, there have been few such campaigns in Philadelphia, and none have been designed to comprehensively evaluate pollution levels across the entire city. As an industrial city with a variety of pollutant sources, Philadelphia is an important setting for such a targeted program. We developed a spatially saturated monitoring campaign to separate impacts of different sources of Nitrogen Dioxide (NO2) (e.g., traffic, port activity) throughout the city. NO2 was monitored across Philadelphia for a two-week period (January 15th to January 29th, 2018) using Ogawa passive samplers. Samplers were placed 8-9 feet high on telephone poles. A total of 50 sites were selected. Selection methods varied, but were based on maximizing spatial variability in NO2 concentrations. Thirty-two were selected using a stratified random sampling approach with geographic information system based indicators of traffic density, proximity to navigable riverways, and population density, all dichotomized at the 80th percentile. Fourteen sites were chosen at varying distances upwind and downwind of a petroleum refinery and the Philadelphia International Airport. Four reference sites were chosen-two in city parks, one in a suburb upwind of Philadelphia, and one within close proximity of an Air Quality System (AQS) regulatory monitor. The mean NO2 concentration across all monitoring sites was 22.79 parts per billion (ppb) (SD=3.75 ppb, min=10.48 ppb, max=30.12 ppb). A subset of sites will continue to be monitored every two weeks throughout 2018. Concentrations will be modeled using land use regression models to predict concentrations at unmonitored locations. This data will be used in future epidemiologic studies of effects of air pollution and other urban exposures on adverse health outcomes, including pediatric asthma.