Spatial and temporal distribution of polycyclic aromatic hydrocarbons and elemental carbon in Bakersfield, California

Abstract

Despite increasing evidence that airborne polycyclic aromatic hydrocarbon (PAH) exposures contribute to adverse health outcomes for sensitive populations, limited data are available on short-term intraurban spatial distributions for use in epidemiologic research. Exposure assessments for airborne PAHs are uncommon because air sampling for PAHs is a labor-, equipment-, and time-intensive task. To address this gap we measured wintertime PAH concentrations during 2010-2011 in Bakersfield, California, USA, a major city in the Southern San Joaquin Valley. Specifically, 58 96-hour integrated PAH samples were collected during 4 time periods at 14 locations from November 2010 to January 2011; duplicates were collected at two sites. We also collected elemental carbon (EC) at the same 14 sites and analyzed the two time periods with the highest ambient PAH pollution. We used linear regression models to quantify the relationship between potential spatial and temporal predictors of PAH concentrations. We found that wintertime PAH concentrations in Bakersfield, CA, are best predicted by meteorological variables and traffic proximity. Our model explains a moderate amount of the variability in the data (R2=0.58), likely reflecting the major sources of PAHs in Bakersfield. We also observed that PAH concentrations were more spatially variable than EC concentrations. Comparing our data to historical monitoring data at one location in Bakersfield showed that the relatively low PAH concentrations during the 2010-2011 winter in Bakersfield is part of a long-term trend in decreasing PAH concentrations.

Immune biomarkers link air pollution exposure to blood pressure in adolescents

“…The study area was confined to a circle with a radius of 20 km, with its center at the ambient air monitoring station located in Fresno, California, one of the most highly polluted areas in the United States, which is operated by the California Air Resources Board (CARB). Continuous daily pollutant concentrations from four air quality monitoring stations located within the Fresno city limits, periodic spatial sampling, and meteorological and geophysical data were used to assign exposures to the following pollutants as described elsewhere [ 13 , 14 ]: 4-, 5-, and 6-ringed polycyclic aromatic hydrocarbons [PAH 456 ], particulate matter with aerodynamic diameter of ≤2.5 μm (PM 2.5 ) , particulate matter with aerodynamic diameter of ≤10 μm (PM 10 ), ozone (O 3 ), carbon monoxide (CO), nitrogen dioxide (NO 2) , and nitrogen oxides (NO x ). Hourly concentrations of particle-bound PAHs were measured at each monitoring station with the PAS2000 (EcoChem Analytics, League City, TX).…”

“…Hourly concentrations of particle-bound PAHs were measured at each monitoring station with the PAS2000 (EcoChem Analytics, League City, TX). Spatial-temporal models that used the air quality data along with meteorological and land-use data, were used to estimate concentrations at each participant’s residence [ 14 ]. Average exposures were estimated for the week and the month preceding each participant’s clinical visit.…”

Air pollution exposure is linked with methylation of immunoregulatory genes, altered immune cell profiles, and increased blood pressure in children

“…Hourly concentrations of particle-bound PAHs were measured at each monitoring station with the PAS2000 (EcoChem Analytics, League City, TX). Spatial–temporal models that used the air quality data along with meteorological and land-use data, were used to estimate concentrations at each participant’s residence 14 . AAP exposures were estimated 1 day prior to each participant’s clinical visit and also averaged over 1 week and 1, 3, 6 and 12 months prior to each participant visit.…”

Source characterization and exposure modeling of gas-phase polycyclic aromatic hydrocarbon (PAH) concentrations in Southern California

“…Studies aimed at developing spatial models of PAH concentrations have previously been conducted (Jedynska et al, 2014; Noth et al, 2016). Few studies, however, have developed LUR models to estimate ambient concentrations of PAHs (Noth et al, 2013).…”

“…Among the studies that model ambient PAH concentrations, all studies modeled particle- as opposed to gas-phase PAHs (Jedynska et al, 2014; Noth et al, 2016; Polidori et al, 2010). The focus of previous studies on particle-bound PAHs was likely due to the concern with carcinogenicity of benzo-a-pyrene, one of the most common particle-bound PAH congeners (ATSDR, 1999).…”