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Background: Traffic-related air pollution (TRAP) is made up of complex mixtures of particulate matter, gases and volatile compounds. However, the effects of TRAP on the cardiopulmonary system in mo...

Background: Epidemiological studies show a strong association between fine particulate matter (PM 2.5 ) air pollution and adverse pulmonary effects. While PM concentration can vary by time and location, PM toxicity has been most recently linked to both physicochemical composition and exposure scenario. To study the relevance of particle characteristics to toxicity, winter PM 2.5 samples were obtained from three geographically similar regions (Sacramento, California, USA; Jinan, Shandong, China; and Taiyuan, Shanxi, China), with typically high atmospheric PM 2.5 emissions. PM extract samples (PM CA , PM SD , and PM SX , respectively) were administered by oropharyngeal aspiration (OPA) to different groups of BALB/C mice, at equal mass concentrations [0 (water vehicle control only) or 20 µg/50 µL], on five different occasions over a two-week period, for a cumulative PM dose of 0 or 100 µg/mouse. Mice were necropsied on Days 1, 2 and 4 after the final exposure, and pulmonary effects were evaluated by bronchoalveolar lavage (BAL), histopathology, quantitative polymerase chain reaction tests, and enzyme-linked immunosorbent assays. Results: Unique differences were noted in the chemical composition for each geographic region with PM SX containing the highest concentration of sulfates (organic and inorganic). A systematic examination of the time lag effects of repeated PM exposure demonstrated unique differences. In mice administered PM SX versus the control, BAL neutrophilia, alveolitis, and bronchiolitis were observed on Days 1 and 4. By Day 4, PM SX -exposed mice also exhibited increased gene expression for multiple inflammatory cytokines/chemokines (interleukin 1 beta, tumor necrosis factor alpha, chemokine C-X-C motif ligands-3 and -5), and increased levels of monocyte chemoattractant protein-1 relative to control-, PM CA -, or PM SD -exposed mice . Conclusions: Direct comparison of the toxic effects of three geographically different PM samples on an equal mass basis demonstrate unique pathobiology with increasing lag time post-exposure. Higher sulfate levels in PM SX versus PM CA and PM SD may contribute to the greater inflammatory responses noted that progressed over time.

Particulate matter (PM) in Imperial Valley originates from a variety of sources such as agriculture, traffic at the border crossing, emissions from the cross-border city of Mexicali, and the drying lakebed of the Salton Sea. Dust storms in Imperial Valley, California regularly lead to exceedances of the federal air quality standards for PM(10) (diameter less than 10 microns). To determine if there are differences in the composition and biological response to Imperial County PM by size, ambient PM samples were collected from a sampling unit stationed in the northern-most part of the valley, South of the Salton Sea. Ultrafine, fine, and coarse PM samples were collected and extracted separately. Chemical composition of each size fraction was obtained after extraction by using several analytical techniques, and biological response was measured by exposing a cell line of macrophages to particles and quantifying subsequent gene expression. Biological measurements demonstrated coarse PM induced an inflammatory response in macrophages measured in increases of inflammatory markers IL-1β, IL-6, IL-8 and CXCL2 expression, whereas ultrafine and fine PM only demonstrated significant increases in expression of CYP1a1. These differential responses were due not only to particle size, but to the distinct chemical profiles of each size faction as well. Community groups in Imperial Valley have already completed several projects to learn more about local air quality, giving residents access to data that provides real-time levels of PM(2.5) and PM(10) as well as recommendations on health-based practices dependent on the current AQI (air quality index). However, to date there is no information on the composition or toxicity of ambient PM from the region. The data presented here could provide more definitive information on the toxicity of PM by size, and further inform the community on local air quality.

Airborne particulate matter (PM) is associated with adverse cardiorespiratory effects. To better understand source-orientated PM toxicity, a comparative study of the biological effects of fine PM (diameter≤2.5μm, PM2.5) collected during the winter season from Shanxi Province, China, and the Central Valley, California, United States, was conducted. The overarching hypothesis for this study was to test whether the chemical composition of PM on an equal mass basis from two urban areas, one in China and one in California, can lead to significantly different effects of acute toxicity and inflammation in the lungs of healthy young mice. Male, 8-week old BALB/C mice received a single 50μg dose of vehicle, Taiyuan PM or Sacramento PM by oropharyngeal aspiration and were sacrificed 24h later. Bronchoalveolar lavage, ELISA and histopathology were performed along with chemical analysis of PM composition. Sacramento PM had a greater proportion of oxidized organic material, significantly increased neutrophil numbers and elevated CXCL-1 and TNF-α protein levels compared to the Taiyuan PM. The findings suggest that Sacramento PM2.5 was associated with a greater inflammatory response compared to that of Taiyuan PM2.5 that may be due to a higher oxidice. Male, 8-week old BALB/C mice received a single 50μg dose of vehicle, Taiyuan PM or Sacramento PM by oropharyngeal aspiration and were sacrificed 24h later. Bronchoalveolar lavage, ELISA and histopathology were performed along with chemical analysis of PM composition. Sacramento PM had a greater proportion of oxidized organic material, significantly increased neutrophil numbers and elevated CXCL-1 and TNF-α protein levels compared to the Taiyuan PM. The findings suggest that Sacramento PM2.5 was associated with a greater inflammatory response compared to that of Taiyuan PM2.5 that may be due to a higher oxidized state of organic carbon and copper content.

Atmospheric particles are frequently collected onto filter and impactor substrates for studies related to the composition, health effects and climate impact of ambient particulate matter (PM). Many of these studies require extraction of that PM from the substrates but available methods have low extraction efficiencies that may lead to compositional and thus toxicity bias. Here, novel PM extraction methods are presented that (a) maximize extraction efficiency, (b) minimize compositional biases in extracted PM, relative to sampled PM and (c) minimize extraction artifacts. Method development was based upon strengths and weaknesses of existing SOPs and current requirements in the field of aerosol health effects research. Extraction objectives were accomplished using a combination of sonication in solvents of varying polarity, selective filtration, liquid-liquid extraction of water-based extracts, solvent removal and final reconstitution of the total extracted PM. Relying largely on intensive gravimetric analyses and comparison to existing SOPs, the new technique has been fully validated on nearly 40 different size-segregated, source-oriented samples collected during two separate seasons in Fresno, CA. Compared to existing methods, and depending on the source, compositionally-specific increases in extraction efficiencies of 10-40% and 20-50% were obtained for the ultrafine and submicron fine PM fractions, respectively, indicating significant increases in total extraction efficiency and significant decreases in compositional bias. © 2014 Elsevier Ltd.

Current particulate matter regulations control the mass concentration of particles in the atmosphere regardless of composition, but some primary and/or secondary particulate matter components are no doubt more or less toxic than others. Testing direct emissions of pollutants from different sources neglects atmospheric transformations that may increase or decrease their toxicity. This work describes a system that conditionally samples particles from the atmosphere depending on the sources or source combinations that predominate at the sampling site at a given time. A single particle mass spectrometer (RSMS-II), operating in the 70-150 nm particle diameter range, continuously provides the chemical composition of individual particles. The mass spectra indicate which sources are currently affecting the site. Ten ChemVol samplers are each assigned one source or source combination, and the RSMS-II controls which one operates depending on the sources or source combinations observed. By running this system for weeks at a time, sufficient sample is collected by the ChemVols for comparative toxicological studies. This paper describes the instrument and algorithmic design, implementation, and first results from operating this system in Fresno, CA, during summer 2008 and winter 2009.

The EPA regulates ambient particulate matter (PM) because substantial associations have been established between PM and health impacts. Presently, regulatory compliance involves broad control of PM emission sources based on mass concentration rather than chemical composition, although PM toxicity is likely to vary depending upon PM physicochemical properties. The overall objective of this study was to help inform source-specific PM emission control regulations. For the first time, source-oriented PM was collected from the atmosphere in Fresno, CA, onto 38 source/size substrates. Mice were exposed via oropharyngeal aspiration to equivalent mass doses [50 μg] of two size fractions: ultrafine (Dp < 0.17μm) and submicron fine (0.17 < Dp < 1 μm) during summer and winter seasons. At 24 hours post-exposure, cellular and biochemical indicators of pulmonary inflammation were evaluated in the bronchoalveolar lavage fluid. Significant inflammatory responses were elicited by vehicle, regional background, and cooking PM sources that were dependent on season and particle size. This is the first study of source-oriented toxicity of atmospheric PM and supports source-specific emissions control strategies.

© 2015 Elsevier Ltd. Collection and subsequent extraction of particulate matter (PM) from filter substrates is a common requirement for invivo and invitro toxicological studies, as well as chemical analyses such as ion chromatography and inductively coupled plasma mass spectrometry. Several filter extraction protocols exist and different laboratories employ different methods, potentially biasing inter-study comparisons. Previous studies have shown significant differences in extraction efficiency between techniques and identified the relevant extraction artifacts. However, a comprehensive inter-comparison of different methods based on the chemical composition of the extracted PM has never been conducted. In the current study, an exhaustive suite of chemical analyses is performed on PM extracted from glass micro-fiber filters using techniques commonly employed in different laboratories: Multi-solvent extraction (MSE) and spin-down extraction (SDE). PM samples were collected simultaneously during field studies conducted in an urban and rural setting using a high-volume PM2.5 sampler. Results show remarkable compositional variance between the PM extracts for all chemical components analyzed, including metals, water soluble ions, polycyclic aromatic hydrocarbons, non-aromatic organics, elemental carbon and organic carbon. Mass closure was greater than 90% for MSE but deviated substantially for SDE. Detailed retrospective gravimetric analysis of archived SDE samples revealed that a process-based loss of PM mass is the root cause of the differences. These losses are shown to be compositionally biased, both externally between different PM mixtures and internally within a given PM mixture. In combination, the results of this study are the first to demonstrate (i) an exhaustive chemical characterization of a single PM extract, (ii) the significance of directly characterizing the extracted PM used in toxicological studies, (iii) the existence of substantial compositional biases between different filter extraction techniques and (iv) the importance of standardizing filter extraction objectives and procedures to avoid introducing study bias into toxicological studies.

During the Pittsburgh Air Quality Study (PAQS), July 2001–September 2002, three co-located instruments analyzed the composition of ambient particulate matter (PM): (1) A single particle mass spectrometer, RSMS-3, was deployed to obtain high-temporal-resolution measurements of single particle size (>1.1 μm) and composition which were correlated with meteorological data to identify sources; (2) PM2.5 and PM10 were collected on cellulose filters using high-volume (hi-vol) samplers, followed by microwave-assisted digestion and analysis by inductively coupled plasma–mass spectrometry (ICP–MS). Positive matrix factorization (PMF) was used to identify possible source categories; and (3) a micro-orifice uniform-deposit impactor (MOUDI) obtained size-distributed samples of PM. Several days of MOUDI filters were selected for microwave-assisted digestion and analysis by ICP–MS. In this paper, sources identified using the single particle data were compared to the PMF results for the hi-vol/ICP–MS data. The strengths of each method were combined to hypothesize the most likely sources of various elements in ambient PM in Pittsburgh. In the final results, Mo and Cr are attributed to local specialty steel facilities; Fe, Mn, Zn, and K are attributed to a steel mill SE of the monitoring station; internally mixed Pb-containing particles are attributed to a major source to the NW; and Ga is attributed to coal combustion sources to the NW. There is a notable lack of oil combustion sources. The MOUDI data were used to resolve discrepancies between the single particle and hi-vol/ICP–MS data concerning the detection of Ti and Se. The hi-vol data showed appreciable Ti and Se masses, but RSMS-3 was unable to detect significant numbers of Ti-containing particles because of their large size, while we hypothesize that the volatility of Se caused it to be distributed more evenly over all emitted particles such that the amount of Se in any individual particle is below the limit of detection.

Recent epidemiological evidence supports the hypothesis that health effects from inhalation of ambient particulate matter (PM) are governed by more than just the mass of PM inhaled. Both specific chemical components and sources have been identified as important contributors to mortality and hospital admissions, even when these endpoints are unrelated to PM mass. Sources may cause adverse health effects via their ability to produce reactive oxygen species, possibly due to the transition metal content of the PM. Our goal is to quantify the oxidative potential of ambient particle sources collected during two seasons in Fresno, CA using the dithiothreitol (DTT) assay. We collected PM from different sources or source combinations into different ChemVol (CV) samplers in real time using a novel source-oriented sampling technique based on single particle mass spectrometry. We segregated the particles from each source-oriented mixture into two size fractions – ultrafine (Dp ≤ 0.17 μm) and submicron fine (0.17 μm ≤ Dp ≤ 1.0 μm) – and measured metals and the rate of DTT loss in each PM extract. We find that the mass-normalized oxidative potential of different sources varies by up to a actor of 8 and that submicron fine PM typically has a larger mass-normalized oxidative potential than ultrafine PM from the same source. Vehicular Emissions, Regional Source Mix, Commute Hours, Daytime Mixed Layer and Nighttime Inversion sources exhibit the highest mass-normalized oxidative potential. When we apportion the volume-normalized oxidative potential, which also accounts for the source's prevalence, cooking sources account for 18–29% of the total DTT loss while mobile (traffic) sources account for 16–28%. When we apportion DTT activity for total PM sampled to specific chemical compounds, soluble copper accounts for roughly 50% of total air-volume-normalized oxidative potential, soluble manganese accounts for 20%, and other unknown species, likely including quinones and other organics, account for 30%. During nighttime, soluble copper and manganese largely explain the oxidative potential of PM, while daytime has a larger contribution from unknown (likely organic) species.

[1] A suite of particulate, gaseous and meteorological measurements during the Pittsburgh Supersite experiment were used to characterize the impact of the 2002 Quebec wildfires on pollutant concentrations and physical and chemical processes dominant in the region. Temporal trends in the number distribution of wildfire particles (isolated using Rapid Single-ultrafine-particle Mass Spectrometry data) combined with CO, NOx and O3 mixing ratios identified two separate periods (Periods I and II) when the measurement site was directly impacted by plumes of relatively unprocessed wildfire emissions; i.e., increases in primary ultrafine wildfire particles, CO and NOx concomitant with a decrease in O3 from intraplume NOx titration. Carbonaceous particle number distributions predominantly associated with vehicular emissions, PM2.5 sulfate mass concentration and SO2 mixing ratio resolved individual components of local and regional sources. Single particle signatures indicated a period of intense atmospheric processing following Period II that caused rapid growth of the ultrafine mode due to simultaneous sulfate and secondary organic mass accumulation, resulting in significant changes to particle physical and chemical properties. Particle growth was concurrent with large increases in O3 and maxima in incoming solar radiation and ambient temperature and is posited to have occurred in situ as the air mass, containing a mixture of urban and wildfire emissions, was advected past the site. In total, the current work demonstrates significant added severity for pollution episodes in an area already burdened by large anthropogenic emission rates due to the impact of the 2002 Quebec wildfires. High levels of atmospheric processing increased sulfate accumulation and SOA formation and brought PM2.5 mass concentrations close to, and O3 mixing ratios in excess of, the National Ambient Air Quality Standards. Projections of increasing wildfire activity under a warming climate may increase the frequency and severity of such events.