Spatial Correlation of Ultrafine Particle Number and Fine Particle Mass at Urban Scales: Implications for Health Assessment

Abstract

Urban BG Near local Rd Near local Rd + restaurant Near arterial Rd Urban st canyon Near highway Near industry Figure S1: Study area map and measurements sites. Measurements of particle number and PM 2.5 mass concentrations are collected during winter of 2017 and 2018. A circle symbol 101 (D-F) LUR predictions, and (G-I) 1-km CTM predictions. In panels C, F, and I , PNC to PM 2.5 102 mass slopes for the various sources (e.g., natural gas, gasoline) are shown from literature 1-5 ; 103 the red lines in these panels are the linear fit of the data/predictions.

Spatiotemporal profiles of ultrafine particles differ from other traffic-related air pollutants: lessons from long-term measurements at fixed sites and mobile monitoring

“…44,76 Long-term xed site and mobile monitoring measurements can advance understanding of the spatiotemporal patterns of various air pollutants. 65,77 While highly resolved spatio-temporal measurements of particle size distributions may be unlikely, a compromise such as the collection of long term measurements of size distributions along a gradient of xed site locations may help us understand the role of primary emissions vs. NPF in contributing to UFP concentrations. Furthermore, recent advances in understanding semivolatile and intermediate volatility precursors, and the emerging recognition of the pivotal role of volatile chemical emissions 72 in urban reactive chemistry might suggest that this issue merits detailed investigation from a chemically resolved perspective as well.…”

Shipping Remains a Globally Significant Source of Anthropogenic PN Emissions Even after 2020 Sulfur Regulation

“…Our study implies that shipping remains as a significant source of anthropogenic PN emissions that should be accounted for in future climate modeling and consideration of health impacts. Recent studies have presented exposure models to ultrafine PN, − and the results from this study may help incorporate PN emissions from shipping in exposure models as well as climate models applying direct PN emission inventories. , The importance of PN emissions from shipping is emphasized by the trend in continental emissions that are dominated by on-road vehicles; for these, exhaust particle filters, leading to a decrease of primary PN by orders of magnitude, are becoming mandatory. Therefore, the relative contribution of ship emissions may become higher in the future.…”

High-Spatial-Resolution Estimates of Ultrafine Particle Concentrations across the Continental United States

“…2 The moderate intracity PNC-PM 2.5 spatial correlation (e.g., average of 267 cities, R 2 = 0.37) is due to similar traffic and combustion-related sources driving intracity gradients of both pollutants. 26,27 However, as these urban emissions are transported over suburban and rural areas on a timescale of several days, the PNC reduces due to dispersion and coagulation and PM 2.5 mass increases due to secondary formation. This reduces the spatial correlation between PNC and PM 2.5 at the regional/national scale.…”

“…Therefore, existing UFP epidemiological studies rely on short-term data collection in specific cities, , which lack the potentially larger urban–rural and intercity contrasts that national estimates may provide. Second, UFP concentrations are highly spatially variable within cities. ,,− Therefore, the spatial patterns of UFP will not be resolved using a traditional national monitoring strategy of a small number (1–5) of sites per city, usually located to capture “urban background” locations. − That approach is reasonable for PM 2.5 since intraurban differences are modest, but is unlikely to capture the variability in UFP concentrations. ,, UFP characterization needs data on both intra- and interurban variations. , Third, previous research indicates some spatial correlation of PM 2.5 mass and UFP ( R 2 ∼ 0.4) at the urban scale, − which may complicate differentiating their independent health effects.…”