Observation of elevated air pollutant concentrations in a residential neighborhood of Los Angeles California using a mobile platform

Abstract

We observed elevated air pollutant concentrations, especially of ultrafine particles (UFP), black carbon (BC) and NO, across the residential neighborhood of the Boyle Heights Community (BH) of Los Angeles, California. Using an electric vehicle mobile platform equipped with fast response instruments, real-time air pollutant concentrations were measured in BH in spring and summer of 2008. Pollutant concentrations varied significantly in the two seasons, on different days, and by time of day, with an overall average UFP concentration in the residential areas of ~33 000 cm−3. The averaged UFP, BC, and NO concentrations measured on Soto St, a major surface street in BH, were 57 000 cm−3, 5.1 µg m−3, and 67 ppb, respectively. Concentrations of UFP across the residential areas in BH were nearly uniform spatially, in contrast to other areas in the greater metropolitan area of Los Angeles where UFP concentrations exhibit strong gradients downwind of roadways. We attribute this “UFP cloud” to high traffic volumes, including heavy duty diesel trucks on the freeways which surround and traverse BH, and substantial numbers of high-emitting vehicles (HEVs) on the surface streets traversing BH. Additionally, the high density of stop signs and lights and short block lengths, requiring frequent accelerations of vehicles, may contribute. The data also support a role for photochemical production of UFP in the afternoon. UFP concentration peaks (5 s average) of up to 9 million particles cm−3 were also observed immediately behind HEVs when they accelerated from stop lights in the BH neighborhood and areas immediately adjacent. Although encounters with HEV during mornings accounted for only about 6% and 17% of time spent monitoring residential areas and major surface streets, HEV contributed to about 28% and 53% of total ultrafine particles measured on the route, respectively. The observation of elevated pollutant number concentrations across the Boyle Heights community highlights how multiple factors combine to create high pollutant levels, and has important human exposure assessment implications, including the potential utility of our data as inputs to epidemiological studies.

Mobile air monitoring data-processing strategies and effects on spatial air pollution trends

“…Change in air quality in city of Hamilton, 2005Hamilton, -2010 Van Background standardization, temporal smoothing Adams et al (2012), Wallace et al (2009) Characterizing pollution in low-income neighborhoods in Ghana Handheld Background standardization, spatial smoothing Arku et al (2008), Dionisio et al (2010) Spatial variability of urban air quality Bicycle Background standardization, spatial smoothing Van Poppel et al (2013) Characterizing exposure zones Electric vehicle Local exhaust plume detection Hu et al (2012) Mobile monitoring is often chosen over other methods for its ability to efficiently obtain data at a high spatial resolution under a variety of different conditions. Vehicle emission factor estimation can be conducted using a number of methods, including chassis dynamometer experiments, tunnel studies, and remote sensing, but mobile monitoring methods are often selected because they enable researchers to characterize in-use emissions of individual vehicles under a variety of operating conditions (Park et al, 2011;Wang et al, 2011Wang et al, , 2012Westerdahl et al, 2009;Wang et al, 2009).…”

“…To characterize this spatial variation, dense networks of stationary monitors can be deployed, but mobile monitoring is often preferred because of the increased spatial flexibility (Baldauf et al, 2008;Choi et al, 2012;Durant et al, 2010;Hagler et al, 2012;Kozawa et al, 2009;Zwack et al, 2011a;Rooney et al, 2012;Westerdahl et al, 2005;Drewnick et al, 2012;Massoli et al, 2012). Broader surveys of ambient air quality are also frequently conducted using mobile monitoring on a scale ranging from neighborhood to country in order to characterize regional concentrations or locate previously unknown hotspots (Hagler et al, , 2010Arku et al, 2008;Adams et al, 2012;Farrell et al, 2013;Drewnick et al, 2012;Van Poppel et al, 2013;Hu et al, 2012).…”

Mobile monitoring for mapping spatial variation in urban air quality: Development and validation of a methodology based on an extensive dataset

“…Mobile measurements are performed with different platforms, e.g. pedestrians (Zwack et al, 2011a), bicycles (Berghmans et al, 2009;Boogaard et al, 2009;Peters et al, 2013;Sullivan and Pryor, 2014), trams (Hagemann et al, 2014;Hasenfratz et al, 2014) and cars (Westerdahl et al, 2005;Hu et al, 2012;Hudda et al, 2014). Mobile measurements are used for a range of different purposes, e.g.…”

Developing High Spatial Resolution Concentration Maps Using Mobile Air Quality Measurements

“…An increasing number of air quality studies use mobile air pollution monitoring. Mobile measurements have several advantages over conventional stationary measurements, including the opportunity for better data coverage, efficient collection of data in close proximity to sources and logistical efficiency (Hagler et al, 2012;Hu et al, 2012;Birmili et al, 2013;Choi et al, 2013;Peters et al, 2013;Brantley et al, 2014;Lähde et al, 2014). Although mobile measurement data can be highly spatially resolved, they are not always presented as high spatial resolution concentration maps.…”

“…Although mobile measurement data can be highly spatially resolved, they are not always presented as high spatial resolution concentration maps. Many studies have presented either data statistics or aggregated data for streets or route segments (Hagler et al, 2012;Hu et al, 2012;Choi et al, 2013;Peters et al, 2013;. Taking advantage of the high spatial resolution of the data offers potential to identify spatial variations and local air pollution hot spots at sub-block scale resolution, which in turn can provide exposure estimates for near-road communities, pedestrians and transit users to elevated levels of pollution near roadways.…”