Measurement and receptor modeling of atmospheric polycyclic aromatic hydrocarbons in urban Kaohsiung, Taiwan

Levels, distributions, and seasonal variations of polycyclic aromatic hydrocarbons (PAHs) in ambient air and pine components

Pine tree (Pinus pinea) components have been used as passive air samples for determining atmospheric polycyclic aromatic hydrocarbon (PAH) concentrations. Our results indicated that pine needles and branches were found to be statistically successful in describing the ambient air. Monthly pine needles, branches (1- and 2-year-old) and ambient air samples were collected for 1 year to identify molecular distributions and temporal concentrations of PAHs in a suburban-industrial area. Annual average Σ₁₄PAH concentrations for pine needles, 1- and 2-year-old branches, and ambient air were 756 ± 232 ng/g DW, 685 ± 350 ng/g DW, 587 ± 361 ng/g DW, and 28.29 ± 32.33 ng/m³, respectively. The order of average Σ₁₄PAH concentrations in the pine tree components was determined as needle > 1-year-old branch > 2-year-old branch. In general, concentrations increased with the rise in the surface area of tree components. In the samples, 3- and 4-ring PAHs were dominant compounds in the ambient air, pine needles, and branches. The annual total fraction of 3- and 4-ring PAHs in the air was 98.5%, while the fraction of 5- and 6-ring PAHs was 1.5%. On the other hand, 3- and 4-ring PAHs in pine needles and branches were 30% or more. The fraction and level of PAHs change with the season. Although needle samples did not show any seasonal trend, PAH levels in other tree components changed with the air temperature. Generally, lower values were observed in warmer seasons in the branch samples. Similarly, ambient air PAH concentrations were higher in the winter season due to heating and adverse meteorological conditions.

Ambient PM2.5 and PM10 bound PAHs in Islamabad, Pakistan: Concentration, source and health risk assessment

Polycyclic aromatic hydrocarbons (PAHs) in ambient particulate matter contribute considerably to human health risk. Simultaneous sampling of ambient PM_2.5/PM₁₀ was done to analyze the Ʃ16PAH across the four seasons of 2017 in Islamabad, Pakistan. The average Ʃ16PAH concentrations in PM_2.5 and PM₁₀ were 25.69 and 40.69 ng m^-3_, respectively. For both PM_2.5 and PM₁₀, the highest PAHs concentration was in winter (45.14, 67.10 ng m^-3), while the lowest was in summer (16.40, 28.18 ng m^-3). Source appointment indicated that vehicular exhaust, i.e., diesel, gasoline and alternatively fuel liquid natural gas (LNG), and compressed natural gas (CNG) combustion was the primary PAHs contributor, whereas biomass burning and fuel combustion (coal, biomass, wood, CNG) from stationary sources were another important sources. Health risk assessment showed that the lifetime cancer risk (LCR) values of PAHs were higher than the acceptable level in all four seasons. LCR values were the highest in winter (9.23 × 10^-4 for PAHs in PM_2.5 and 13.98 × 10^-4 for PAHs in PM₁₀) which were 9 and 13 times higher than tolerable cancer risk level respectively, and they were 2-3 times higher than the acceptable values in other seasons.

Application of thermal desorption methods for airborne polycyclic aromatic hydrocarbon measurement: A critical review

Thermal desorption (TD) is a universal solvent-free pre-concentration technique. It is often used to pre-concentrate semi-volatile and volatile organic compounds in various sample types. Polycyclic aromatic hydrocarbons (PAHs) are widespread contaminants from incomplete combustion of organic matter and fossil fuel, which have carcinogenic effects on human health. Conventional methods for determining PAHs, represented by solvent extraction, are gradually being replaced by solvent-free methods, typically the TD technique, because of TD's many advantages, including time savings and environmentally friendly treatment. This work presents an extensive review of the universal methods used to determine PAHs in the atmosphere based on the TD technique. The methods currently used for collection and detection of both gas- and particle-phase PAHs in the air are critically reviewed. In addition, the operating parameters of the TD unit are summarized and discussed. The design shortcomings of existing studies and the problems that researchers should address are presented, and promising alternatives are suggested. This paper also discusses important parameters, such as reproducibility and limit of detection, that form a crucial part of quality assurance. Finally, the limitations and the future prospects of the TD technique for use in airborne PAH analyses are addressed. This is the first review of the latest developments of the TD technique for analysis of PAHs and their derivatives in the atmosphere.

Source Characterization and Exposure Modeling of Gas-Phase Polycyclic Aromatic Hydrocarbon (PAH) Concentrations in Southern California

Airborne exposures to polycyclic aromatic hydrocarbons (PAHs) are associated with adverse health outcomes. Because personal air measurements of PAHs are labor intensive and costly, spatial PAH exposure models are useful for epidemiological studies. However, few studies provide adequate spatial coverage to reflect intra-urban variability of ambient PAHs. In this study, we collected 39-40 weekly gas-phase PAH samples in southern California twice in summer and twice in winter, 2009, in order to characterize PAH source contributions and develop spatial models that can estimate gas-phase PAH concentrations at a high resolution. A spatial mixed regression model was constructed, including such variables as roadway, traffic, land-use, vegetation index, commercial cooking facilities, meteorology, and population density. Cross validation of the model resulted in an R² of 0.66 for summer and 0.77 for winter. Results showed higher total PAH concentrations in winter. Pyrogenic sources, such as fossil fuels and diesel exhaust, were the most dominant contributors to total PAHs. PAH sources varied by season, with a higher fossil fuel and wood burning contribution in winter. Spatial autocorrelation accounted for a substantial amount of the variance in total PAH concentrations for both winter (56%) and summer (19%). In summer, other key variables explaining the variance included meteorological factors (9%), population density (15%), and roadway length (21%). In winter, the variance was also explained by traffic density (16%). In this study, source characterization confirmed the dominance of traffic and other fossil fuel sources to total measured gas-phase PAH concentrations while a spatial exposure model identified key predictors of PAH concentrations. Gas-phase PAH source characterization and exposure estimation is of high utility to epidemiologist and policy makers interested in understanding the health impacts of gas-phase PAHs and strategies to reduce emissions.

Sources and spatial distribution of particulate polycyclic aromatic hydrocarbons in Shanghai, China

Atmospheric particulate polycyclic aromatic hydrocarbons (PAHs) have been drawing sustained attention due to their health risk and effects on air pollution. It is essential to determine the main sources and reduce atmospheric levels of PAHs to protect human health. PAHs in PM_2.5 have been detected at five sites located in five districts in Shanghai, a modern metropolitan city in China. Spatial and temporal variations of composition profiles and sources of PAHs at each site in each season were investigated. The results showed that atmospheric particulate PAHs level in Shanghai was the lowest in summer and the highest in winter, dominated by high molecular weight (HMW) PAHs. Analysis with a combination of coefficients of Pearson's correlation and coefficient of divergences indicated heterogeneous spatial and temporal distribution for LMW PAHs and homogenous distribution for HMW PAHs. Diagnostic ratios and positive matrix factorization (PMF) model both identified pyrogenic sources as the main contributor of PAHs in Shanghai, with vehicular source contribution of 32-43% to the total PAHs annually and around 20% from biomass burning emissions in urban and urban buildup areas. While in winter, coal combustion and biomass burning could act as two major sources of PAHs in suburban areas, which could contribute to >70% of total PAHs measured in PM_2.5 in Shanghai.

Winter Polycyclic Aromatic Hydrocarbon-Bound Particulate Matter from Peri-urban North China Promotes Lung Cancer Cell Metastasis

On the basis of the close relationship between human exposure to high concentrations of small particulate matter (PM) and increased lung cancer mortality, PM was recently designated as a Group I carcinogen. Considering that PM is highly heterogeneous, the potential health risks of PM promoting tumor metastasis in lung cancer, as well as its chemical characteristics, remain elusive. In the present study, we collected PM2.5 and PM10 in a peri-urban residential site of Taiyuan and determined the concentration and source of polycyclic aromatic hydrocarbons (PAHs). The results indicated that 18 PAHs, ranging from 38.21 to 269.69 ng/m(3) (for PM2.5) and from 44.34 to 340.78 ng/m(3) (for PM10), exhibited seasonal variations, and the PAHs in winter PM mainly originated from coal combustion. We calculated the benzo(a)pyrene-equivalent (BaPeq) and found that the PAH-bound PM in winter exhibited higher carcinogenic risks for humans. Following this result, in vitro bioassays demonstrated that PM2.5 and PM10 induced A549 cell migration and invasion, and the mechanism involved reactive oxygen species (ROS)-mediated epithelial-to-mesenchymal transition (EMT) activation and extracellular matrix (ECM) degradation. Our data indicate the potential risk for winter PAH-bound PM from peri-urban North China promoting lung cancer cell metastasis and reveal a mechanistic basis for treating, ameliorating, or preventing outcomes in polluted environments.

Nature and sources of particle associated polycyclic aromatic hydrocarbons (PAH) in the atmospheric environment of an urban area

The total PAH associated to the airborne particulate matter (PM10) was apportioned by one receptor model based on positive matrix factorization (PMF) in an urban environment (Zaragoza city, Spain) during February 2010-January 2011. Four sources associated with coal combustion, gasoline, vehicular and stationary emissions were identified, allowing a good modelling of the total PAH (R(2) = 0.99). A seasonal behaviour of the four factors was obtained with higher concentrations in the cold season. The NE direction was one of the predominant directions showing the negative impact of industrial parks, a paper factory and a highway located in that direction. Samples were classified according to hierarchical cluster analysis obtaining that, episodes with the most negative impact on human health (the highest lifetime cancer risk concentrations), were produced by a higher contribution of stationary and vehicular emissions in winter season favoured by high relative humidity, low temperature and low wind speed.

A seasonal study of polycyclic aromatic hydrocarbons in PM(2.5) and PM(2.5-10) in five typical cities of Liaoning Province, China

Fourteen polycyclic aromatic hydrocarbons (PAHs) in PM(2.5) and PM(2.5-10) samples collected in five cities (Shenyang, Anshan, Jinzhou, Fushun and Dalian), Liaoning Province, China in 2004 and 2005 were analyzed by using a HPLC equipped with fluorescence and UV detectors. Results showed total PAHs concentrations in PM(2.5) and PM(2.5-10) were in the range of 75.32-1900.89 ng m(-3) and 16.74-303.24 ng m(-3), respectively. 90% of the total PAHs were in PM(2.5). PAHs in PM(2.5) had a winter to summer ratio varying from 6.5 to 125.8 while PAHs in PM(2.5-10) had a ratio ranging from 1.7 to 37.6. Total PAHs concentrations were most abundant at residential/commercial sites and were fewest at an industrial site for both PM(2.5) and PM(2.5-10). Urban background sites showed unexpected higher PAHs concentrations. Total BaP equivalent concentration (BaPeq) for PM(2.5) ranged from 7.80 to 88.42 ng m(-3) in different function zones. Similarities of PAHs profiles between sampling sites and between fine and coarse fractions were compared by coefficient of divergence which indicated that remarkable differences in PAHs compositions existed. Principal component analysis (PCA) associated with diagnostic ratios revealed coal combustion and vehicle emission were the major sources for PM(2.5) and PM(2.5-10) associated PAHs.

Sizes and polycyclic aromatic hydrocarbon composition distributions of nano, ultrafine, fine, and coarse particulates emitted from a four-stroke motorcycle

Thus, this study was undertaken to determine the size distribution, concentration, species, and carcinogenic potency of particulate matter and particle-bound polycyclic aromatic hydrocarbons (PAHs) emitted from 4-st/mc at various speeds (idle, 15 km/h, 30 km/h). Approximately 80% of the particles emitted from the that is, they are primary inhalable particulates. The particle total number concentrations (TNCs) emitted while idling and at 15 and 30 km/h were 2.07 x 10⁴, 2.35 x 10⁴, and 2.60 x 10⁴ #/cm³, respectively; i.e., they increased at elevated speeds. Notably, most of the particles emitted at 30 km/h had diameters of less than 0.65 μm and contained higher percentages of total PAHs. Excluding incomplete combustion, we suspected that some of the lower-molecular-weight PAHs [phenanthrene (PA), anthracene (Ant), pyrene (Pyr)] obtained in the fine particles at idle originated from unburned 95-octane unleaded fuel. When operated at 15 km/h, pyrolysis of the PAHs dominated, resulting in increased amounts of medium-molecular-weight PAHs {fluorene (FL), Pyr, benz[a]anthracene (BaA), chrysene (CHR)} in the ultrafine particles. Furthermore, at 30 km/h, more pyrosynthesis products {benzo[a]pyrene (BaP), indeno[1,2,3,-cd]pyrene (IND), dibenz[a,h]anthracene (DBA)}, induced through combustion at the correspondingly higher temperature, were exhausted with the nanoparticles. Although the total concentrations of BaP-equivalent emissions were inconsistent with the total PAHs, the nanoscale-sized particulates emitted from the 4-st/mc at higher speeds had the strongest PAH-related carcinogenic potencies, which should be a great concern.