Increased di-(2-ethylhexyl) phthalate exposure poses a differential risk for adult asthma clusters.

BACKGROUND: DEHP, a common plasticizer known for its hormone-disrupting properties, has been associated with asthma. However, a significant proportion of adult asthma cases are "non-atopic", lacking a clear etiology. METHODS: In a case-control study conducted between 2011 and 2015, 365 individuals with current asthma and 235 healthy controls from Kaohsiung City were enrolled. The control group comprised individuals without asthma, Type 2 Diabetes Mellitus (T2DM), hypertension, or other respiratory/allergic conditions. The study leveraged asthma clusters (Clusters A to F) established in a prior investigation. Analysis involved the examination of urinary DEHP metabolites (MEHP and MEHHP), along with the assessment of oxidative stress, sphingolipid metabolites, and inflammatory biomarkers. Statistical analyses encompassed Spearman's rank correlation coefficients, multiple logistic regression, and multinomial logistic regression. RESULTS: Asthma clusters (E, D, C, F, A) exhibited significantly higher ORs of MEHHP exposures compared to the control group. When considering asthma-related comorbidities (T2DM, hypertension, or both), patients without comorbidities demonstrated significantly higher ORs of the sum of primary and secondary metabolites (MEHP + MEHHP) and MEHHP compared to those with asthma comorbidities. A consistent positive correlation between urinary HEL and DEHP metabolites was observed, but a consistent negative correlation between DEHP metabolites and selected cytokines was identified. CONCLUSION: The current study reveals a heightened risk of MEHHP and MEHP + MEHHP exposure in specific asthma subgroups, emphasizing its complex relationship with asthma. The observed negative correlation with cytokines suggests a new avenue for research, warranting robust evidence from epidemiological and animal studies.

Environmental risks and sphingolipid signatures in adult asthma and its phenotypic clusters: a multicentre study.

BACKGROUND: Adult asthma is phenotypically heterogeneous with unclear aetiology. We aimed to evaluate the potential contribution of environmental exposure and its ensuing response to asthma and its heterogeneity. METHODS: Environmental risk was evaluated by assessing the records of National Health Insurance Research Database (NHIRD) and residence-based air pollution (particulate matter with diameter less than 2.5 micrometers (PM2.5) and PM2.5-bound polycyclic aromatic hydrocarbons (PAHs)), integrating biomonitoring analysis of environmental pollutants, inflammatory markers and sphingolipid metabolites in case-control populations with mass spectrometry and ELISA. Phenotypic clustering was evaluated by t-distributed stochastic neighbor embedding (t-SNE) integrating 18 clinical and demographic variables. FINDINGS: In the NHIRD dataset, modest increase in the relative risk with time-lag effect for emergency (N=209 837) and outpatient visits (N=638 538) was observed with increasing levels of PM2.5 and PAHs. Biomonitoring analysis revealed a panel of metals and organic pollutants, particularly metal Ni and PAH, posing a significant risk for current asthma (ORs=1.28-3.48) and its severity, correlating with the level of oxidative stress markers, notably Nε-(hexanoyl)-lysine (r=0.108-0.311, p<0.05), but not with the accumulated levels of PM2.5 exposure. Further, levels of circulating sphingosine-1-phosphate and ceramide-1-phosphate were found to discriminate asthma (p<0.001 and p<0.05, respectively), correlating with the levels of PAH (r=0.196, p<0.01) and metal exposure (r=0.202-0.323, p<0.05), respectively, and both correlating with circulating inflammatory markers (r=0.186-0.427, p<0.01). Analysis of six phenotypic clusters and those cases with comorbid type 2 diabetes mellitus (T2DM) revealed cluster-selective environmental risks and biosignatures. INTERPRETATION: These results suggest the potential contribution of environmental factors from multiple sources, their ensuing oxidative stress and sphingolipid remodeling to adult asthma and its phenotypic heterogeneity.

Transport and fluxes of terrestrial polycyclic aromatic hydrocarbons in a small mountain river and submarine canyon system.

Polycyclic aromatic hydrocarbon (PAH) concentrations in the Gaoping River were investigated in the wet and dry seasons. PAH characteristics allowed us to trace the particulate matter transported in a river-sea system containing a small mountain river, continental shelf, and submarine canyon. PAH signatures of the Gaoping River showed that particles were rapidly transported from the high mountain to the Gaoping coastal areas in the wet season, even arriving at the deep ocean via the Gaoping Submarine Canyon. By contrast, in the dry season, the particles were delivered quite slowly and included mostly pyrogenic contaminants. The annual riverine flux estimates for PAHs were 2241 kg in the Gaoping river-sea system. Only 18.0 kg were associated with the dissolved phase; the rest was bound onto particles. The fluxes caused by typhoons and their effects accounted for 20.2% of the dissolved and 68.4% of the particulate PAH fluxes from the river. Normalized partition coefficients for organic carbon suggested that PAHs were rigid on the particles. Distinct source characteristics were evident for PAHs on riverine suspended particles and coastal surface sediments: the particles in the wet season (as background signals) were similar to petrogenic sources, whereas the particles in the dry season had characteristics of coal burning and vehicular emissions. The sediments in the northwestern shelf were similar to pyrogenic sources (including vehicular emissions and coal and biomass burning), whereas the sediments in the canyon and southeastern shelf arose from mixed sources, although some diesel signature was also evident.

Complexation-flocculation combined with microwave-assisted headspace solid-phase microextraction in determining the binding constants of hydrophobic organic pollutants to dissolved humic substances.

The binding constants, KDOC, of selected polycyclic aromatic hydrocarbons (PAHs)-phenanthrene, anthracene, fluoranthene, and pyrene-to dissolved humic substances (DHS) were determined by complexation-flocculation combined with microwave-assisted headspace solid-phase microextraction (CF-MA-HS-SPME). The results obtained are comparable with KDOC data reported in the literature. No disruption of the PAH to DHS binding equilibrium was observed during the complexation-flocculation process. The present study, which is the first to determine KDOC by CF-MA-HS-SPME, provides an alternative approach to determine the KDOC of PAHs. CF-MA-HS-SPME provides some advantages over other methods, such as no limitation of fluorescent compounds, greater determination speed, and the capability of measuring various compounds simultaneously.

Impacts of emerging contaminants on surrounding aquatic environment from a youth festival.

The youth festival as we refer to Spring Scream, a large-scale pop music festival, is notorious for the problems of drug abuse and addiction. The origin, temporal magnitudes, potential risks and mass inputs of emerging contaminants (ECs) were investigated. Thirty targeted ECs were analyzed by solid-phase extraction and liquid chromatography coupled to tandem mass spectrometry (SPE-LC-MS/MS). Sampling strategy was designed to characterize EC behavior in different stages (before and after the youth festival), based on multivariate data analysis to explore the contributions of contaminants from normal condition to the youth festival. Wastewater influents and effluents were collected during the youth festival (approximately 600 000 pop music fans and youth participated). Surrounding river waters are also sampled to illustrate the touristic impacts during peak season and off-season. Seasonal variations were observed, with the highest concentrations in April (Spring Scream) and the lowest in October (off-season). Acetaminophen, diclofenac, codeine, ampicillin, tetracycline, erythromycin-H2O, and gemfibrozil have significant pollution risk quotients (RQs > 1), indicating ecotoxicological concerns. Principal component analysis (PCA) and weekly patterns provide a perspective in assessing the touristic impacts and address the dramatic changes in visitor population and drug consumption. The highest mass loads discharged into the aquatic ecosystem corresponded to illicit drugs/controlled substances such as ketamine and MDMA, indicating the high consumption of ecstasy during Spring Scream.

Source identification and characterization of atmospheric polycyclic aromatic hydrocarbons along the southwestern coastal area of Taiwan - with a GMDH approach.

Air samples of polycyclic aromatic hydrocarbons (PAHs) were collected from May 2008 to April 2009 in the Kaohsiung coastal area of Taiwan to establish a dataset. Sample analysis suggested that PAH composition (dominated by 3-ring PAHs) and seasonal patterns (high concentration in winter and low concentration in summer) are nearly identical to those previously reported (Lai et al., 2011), except for a case of road construction during the sample period. The predominant sources of PAHs were identified by isomer ratio, HCA and PCA analyses as vehicle emissions and coal/wood combustion. According to the results of parameters selection via the Group Method of Data Handling (GMDH), the variations in gaseous PAHs and particulate PAHs were related mainly to meteorological conditions and to routine monitoring of air pollutant concentrations, respectively. A comparison of model prediction accuracy between particulate and gaseous PAHs suggests better prediction for particulate PAHs than gaseous PAHs, due to dramatic variation in meteorological conditions which results in higher prediction uncertainty for gaseous PAHs. Model predictions of PAH concentrations showed satisfactory agreement with measured data, except for specific incidents, such as joss paper burning events. The results of this study suggest that the GMDH model may be applied to PAH concentration prediction for the study area and may be applicable for other countries based on routine monitoring of air pollutant concentrations and meteorological conditions.

A study of peatland-derived dissolved organic matter from headstream to sea using multiple analytical tools.

The River Thurso, North Scotland, receives substantial terrestrial deliveries of dissolved organic matter (DOM) leached from Europe's most extensive blanket bogs. The relatively short distance between peatlands and coastal ocean offers potential for research to investigate source-to-sea processing of terrigenous dissolved organic carbon (DOC). Here, we determined DOC concentrations in the bulk (< 0.4 µm), truly dissolved (< 5 kDa), and colloidal fraction (5 kDa - 0.4 µm) as well as DOM absorbance and fluorescence spectra during two river catchment surveys and two corresponding coastal plume surveys, in early spring (1st sampling period) and late spring (2nd sampling period). DOC concentrations ranged from 79 to 3799 µM in early spring and from 115 to 5126 µM in late spring. DOM exhibited conservative mixing across the plume in both surveys, but the plume extended further offshore in the second survey due to a pulse of freshwater caused by recent rainfall. Fluorescence excitation-emission matrices (EEMs) and fluorescence indices revealed that the flushed DOM was humic-like, recently synthesized DOM. Coupled with C/N ratio analyses and molecular weight fractionation, the fluorescence indices also provided evidence for the gradual altering of DOM characteristics along the bog - headstream - loch - river continuum. The same analytical tools revealed that seasonal variations occurred within the DOM pool of marine origin, i.e., greater abundance of low-molecular weight bacterial or algal DOM in the late spring survey. The time scale of such variations relative to the flushing time of water through the aquatic continuum should be taken into account when interpreting the DOM property-salinity distributions of major river plumes.

Diffusive exchange of PAHs across the air-water interface of the Kaohsiung Harbor lagoon, Taiwan.

Instantaneous air-water polycyclic aromatic hydrocarbons (PAHs) exchange fluxes were calculated in 22 pairs of ambient air and water samples from Kaohsiung Harbor lagoon, from December 2003 to January 2005. The highest net volatilization (3135 ng m(-2) day(-1)) and absorptive (-1150 ng m(-2) day(-1)) fluxes in the present study were obtained for the three-ring PAH phenanthrene on 7 April and 27 January 2004, respectively. All PAH diffusive fluxes for three-ring PAHs except phenanthrene were mainly volatilization exchange across the air-water interface. Phenanthrene and the four-ring PAHs were absorbed primarily from the atmosphere and deposited to the surface water, although some minor volatilization fluxes were also observed. Differences in flux magnitude and direction between the dry and wet seasons were also evident for PAHs. Strong absorptive/weaker volatilization PAH fluxes occurred in the dry season, but the opposite was found in the wet season. The mean daily PAH diffusive fluxes were an in flux of -635 ng m(-2) day(-1) in the dry season and an efflux of 686 ng m(-2) day(-1) in the wet season. The integrated absorbed and emitted fluxes of PAHs for harbor lagoon surface waters in the dry and wet seasons were 3.1 kg and 3.4 kg, respectively. Different from water bodies located in temperate zone, phenanthrene diffusive fluxes in Kaohsiung Harbor lagoon was favored in volatilization from surface waters during the wet season (April to September) because of scavenging by precipitation and dilution by prevailing southwesterly winds. In addition, this study used both of salinity and temperature to improve estimation of Henry's law constants (H) of PAHs in a tropical coastal area and show that correction for salinity produced 13-15% of differences in H values.

Concentrations of polycyclic aromatic hydrocarbon in the surface sediments from inter-tidal areas of Kenting coast, Taiwan.

The main objective of this study was to investigate the concentrations of polycyclic aromatic hydrocarbons (PAHs) in inter-tidal sediments of the Kenting coast, Taiwan, to assess the levels and origin of PAHs, and to provide useful information on the potential ecological risk of PAHs to benthic organisms. The total concentrations of 38 PAHs ranged from 0.2 to 493 ng/g dry weight. The high variation in total PAH concentrations was caused by the sand content of the sediment in the area. Compared with other coasts and bays in the world, the concentrations of PAHs in the inter-tidal surface sediment of the Kenting coast is low to moderate. Based on the sediment quality guidelines, the total PAH concentrations were below the effects range low value, indicating that the PAH levels in the Kenting area were within minimal effects ranges for benthic organisms. Principal component analysis and isomer ratios were analyzed to identify the contamination source in the inter-tidal surface sediment of the Kenting coast. The results of compounds' pattern and origin analysis suggest that the source of PAHs in the inter-tidal surface sediment of the Kenting coast is the combustion of petroleum and biomass.

Fifty-year change in air pollution in Kaohsiung, Taiwan.

The change in air quality in cities can be the product of regulation and emissions. Regulations require enforcement of emission reduction, but it is often shifting economic and societal structures that influence pollutant emissions. This study examines the long-term record of air pollutants in Kaohsiung, where post-war industrialisation increased pollution substantially, although improvements are observed in recent decades as the city moved to a more mixed economy. The study tracks both gases and particles across a period of significant change in pollution sources in the city. Concentrations of SO2 and aerosol SO42- were especially high ~1970, but these gradually declined, although SO42- to a lesser extent than its precursor, SO2. While twenty-first century emissions of SO2 and NOx have declined, this has been less so for NH3, because it arises from predominantly agricultural sources. The atmosphere in Kaohsiung continues to have high concentrations of O3, and these have risen in the city, likely a product of less titration by NO. The changes have meant that ozone has become an increasing threat to health and agriculture. Despite a potential for producing (NH4)2SO4 and NH4NO3 aerosols, a product of a relatively constant supply of NH3, visibility has improved in recent years. Emissions of SO2 and NOx should continue to be reduced, as these strongly affect the amount of fine secondary aerosol. However, the key problem may be ozone, which is difficult to control as it requires careful consideration of the balance of NOx and hydrocarbons so important to its production.

Air quality in a hospital dental department.

Background/purpose: Documented studies demonstrated that particulate matter 2.5 (PM2.5) are relatively high in dental clinics. However, the PM2.5 composition is unclear. This study aimed to evaluate the dental department's air quality in a teaching hospital. Materials and methods: The SKC AirChek XR5000 pumps and canister samplers were used to collect PM2.5 and volatile organic compounds (VOCs). The PM2.5 composition analysis (polycyclic aromatic hydrocarbons (PAHs) and metals) was conducted, and in the dental clinic and waiting room, the air quality comparison was investigated. Moreover, the dental clinic's air quality was compared before and after air purifier use. Results: In the dental clinic and waiting room, the results revealed high PM2.5 concentration exceeding the standard of the United States Environmental Protection Agency (USEPA) (35 µg/m3); the values were 41.08-108.23 µg/m3 and 17.89-62.72 µg/m3, respectively. In both investigated locations, VOCs had no significant difference. Among 16 priority PAHs, the result indicated high level of benzo(b)fluoranthene (B(b)f), benzo(k)fluoranthene (B(k)f), benzo(a)pyrene (B(a)p), and indenopyrene (IP). B(b)f and B(k)f and lead (Pb) concentrations were detected with a significant difference in the clinic as compared to the waiting room. In addition, after air purifier use, the B(b)f concentration in the dental clinic reduced from 0.08 to 0.42 ug/m3 to 0.06-0.18 ug/m3 (P < 0.05). Conclusion: For dental practitioners, an appropriated air quality regulation needs to be considered, due to high air pollutant concentration. In addition, using air purifier can efficiently reduce air pollutants.

Seasonal variation of atmospheric polycyclic aromatic hydrocarbons along the Kaohsiung coast.

Thirty-three air samples were collected by high-volume samplers from May 2007 to June 2008 in the coastal area of southwest Taiwan and analyzed for total suspended particulates (TSP) and polycyclic aromatic hydrocarbons (PAHs). Concentrations of TSP and total PAHs ranged from 40.4 to 251 µg m(-3) and 1.86-56.4 ng m(-3), respectively. Except for joss paper burning during the religious celebration of Ghost Month, which resulted in the highest concentration of PAHs in the summer of 2007, a seasonal variation in total PAH concentration was observed over this study period, with the highest concentrations in winter and the lowest in summer. Because of the geographical and climatic characteristics of the sampling site, monsoon activities modulate the seasonal variations of PAHs. Diagnostic ratios showed that PAHs in the atmosphere of the Kaohsiung coastal area arose predominantly from vehicle emissions (mainly from diesel exhaust), joss paper burning, and coal/wood combustion. The results of hierarchical cluster analysis (HCA) and principal component analysis (PCA) indicated that the sampling days could be divided into three groups and that the major source identification of PAHs was the same as the identification by diagnostic ratios. In addition, the results of HCA and PCA suggest that the samples collected with a prevailing northerly or northeasterly wind direction contain both local emissions and those from neighboring sources. On the other hand, the cases related to westerly or northwesterly winds indicated that local emission was the major source for the sampling site.

Temporal and vertical variations of polycyclic aromatic hydrocarbon at low elevations in an industrial city of southern Taiwan.

Considered that human activities mostly occur below building heights, the objective of this study was to investigate the temporal variations of fine particular matter (PM2.5)-associated polycyclic aromatic hydrocarbons (PAHs) and benzo[a]pyrene-equivalent (BaPeq) concentrations at four different elevations (6.1, 12.4, 18.4, and 27.1 m) in Kaohsiung City, the largest industrial city of southern Taiwan. Temperature variation was critical for the PM2.5-associated PAH concentrations, which were dominated by benzo[g,h,i]perylene (0.27 ± 0.04 ng m-3 and 24.43% of the total concentration) and other high molecular weight (HMW) species. The PM2.5-associated BaPeq was dominated by 5-ring PAH (36.09%). The PM2.5-associated PAH and BaPeq concentrations at all elevations were significantly increased in winter. In the night, the correlations between the PM2.5-associated PAH concentrations and atmospheric temperatures became negatively stronger, notably at lower elevations (r = - 0.73 ~ - 0.86), whereas the BaPeq during daytime and nighttime were not changed significantly in most months. The PAHs analysis with different PM sizes demonstrated the importance of smaller particles such as PM2.5. The meteorological variation was more important than elevation to influence the low-elevation PM2.5-associated PAH and BaPeq concentrations in an urban area like Kaohsiung City, as the two concentrations were dominated by the PAHs with HMWs and those 5-ring species, respectively.

Impact of Annual Exposure to Polycyclic Aromatic Hydrocarbons on Acute Exacerbation Frequency in Asthmatic Patients.

PURPOSE: Exposure to polycyclic aromatic hydrocarbons (PAHs) associated with ambient air particulate matter (PM) poses significant health concerns. Increased acute exacerbation (AE) frequency in asthmatic patients has been associated with ambient PAHs, but which subgroup of patients are particularly susceptible to ambient PAHs is uncertain. We developed a new model to simulate grid-scale PM2.5-PAH levels in order to evaluate whether the severity of asthma as measured by the Global Initiative of Asthma (GINA) levels of treatment is related to cumulative exposure of ambient PAHs. METHODS: Patients with asthma residing in the northern Taiwan were reviewed retrospectively from 2014 to 2017. PM2.5 were sampled and analysed for PAHs twice a month over a 72-hour period, in addition to collecting the routinely monitored air pollutant data from an established air quality monitoring network. In combination with correlation analysis and principal component analysis, multivariate linear regression models were performed to simulate hourly grid-scale PM2.5-PAH concentrations (ng/m3). A geographic information system mapping approach with ordinary kriging interpolation method was used to calculate the annual exposure of PAHs (ng/m). RESULTS: Among the 387 patients with asthma aged 18 to 93 (median 62), 97 subjects were treated as GINA step 5 (24%). Asthmatics in GINA 5 subgroup with high annual PAHs exposure were likely to have a higher annual frequency of any AE (1 (0-12), p<0.0001). Annual PAHs exposure was correlated with the annual frequency of any exacerbation (r=0.11, p=0.02). This was more significant in the GINA 5 subgroup (r=0.29, p=0.005) and in the GINA 5 subgroup with severe acute exacerbations (r=0.51, p=0.002). Annual PAHs exposure, severe acute exacerbation and GINA steps were independent variables that predict annual frequency of any exacerbation. CONCLUSION: Asthmatic patients in the GINA 5 subgroup with acute exacerbations were more susceptible to the effect of environmental PAHs on their exacerbation frequency. Reducing environmental levels of PAHs will have the greatest impact on the more severe asthma patients.

Evidence for strong but dynamic iron-humic colloidal associations in humic-rich coastal waters.

This study investigated the physicochemical forms of dissolved iron in the coastal plume (salinity = 28-35) of a small river draining a peat-rich catchment. Speciation information was obtained through a combination of fractionation by crossflow filtration (CFF) along with voltammetric detection of either naturally occurring iron-humic complexes (July survey) or known, synthetic complexes (September survey) formed by titrating the samples with the competing ligand 2-(2-thiazolylazo)-p-cresol (TAC). The majority of colloidal iron (>5000 Da) was present as iron-humic complexes supplied by the river and showing uniform conditional stability constants throughout the plume (log K'(Fe'HS) = 11.3 ± 0.1, i.e. log K(Fe3+HS) = 21.3 ± 0.1). Noncolloidal or soluble iron was strongly complexed to ligands of marine origin with log K'(Fe'HS) = 11.9 ± 0.1. Equilibrium of the total iron pool with the added TAC ligand was achieved in all but the highest salinity sample, albeit more slowly for colloidal than for soluble iron. In addition, measurements of humic like fluorescence suggested that the conformation of colloids could change over time as a result of dissociation of the iron-humic associations. These results are consistent with the concept that iron in coastal waters is strongly but reversibly bound to humic substances and therefore may be available for complexation by siderophore-type ligands released by microorganisms.

A preliminary assessment of polycyclic aromatic hydrocarbon distribution in the kenting coral reef waters of southern Taiwan.

This distribution and variation of 45 polycyclic aromatic hydrocarbons (PAHs) in the waters of Kenting coral reefs were investigated by using sensitive research-grade sampling and analytical methods. The concentration levels of total PAHs (including particulate and dissolved PAHs) in the Kenting waters were relatively low, ranging from 2.2 to 34.4 ng/L. There was no significant spatial difference in PAH concentrations among the sampling stations, even between the surface and bottom waters. The fraction of dissolved PAHs on average was greater than that of particulate PAHs due to the small amount of total suspended particles. The partition coefficients between the particulate and dissolved phase (log K(oc)) were positively correlated with their log K(ow) values (r(2) = 0.67, n = 80), except for the more hydrophobic PAHs with log K(ow) values greater than 5.91. Results of principal component analysis indicate that the patterns of particulate PAH compositions were similar through the Kenting waters in the fall and winter, whereas there was a significant spatial difference between the spring and summer samples, which might be affected by a combination of land runoff and coastal currents. PAHs along the Kenting coasts were dominated by low-molecular PAHs, which have higher solubility than high-molecular PAHs. Based on isomer ratios, analysis of the source of PAHs in the Kenting coastal waters demonstrated that the PAHs come mostly from petroleum and, to a lesser degree, from combustion.

Enrichment behavior of contemporary PAHs and legacy PCBs at the sea-surface microlayer in harbor water.

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the sea-surface microlayer (SML) and sub-surface water (SSW) were analyzed in and around Kaohsiung Harbor. The results confirm SML enrichments for PAHs, but PCBs less significantly, since PAHs are still produced while PCBs had banned years ago. However, PCBs still leak to the environment from contaminated sites. The results showed the sources and transport of PAHs and PCBs were different, but both are enriched in the SML. Total particulate PAHs at most sites are below the toxicity thresholds, with a few individual PAHs between the effects range-low and effect range-median even higher than the effect range-median. Total particulate PCBs might cause occasionally adverse effects in sensitive species and pose a risk to the organisms. The particulate phase in the SML poses a higher risk to the marine ecosystem than in the SSW although not all organisms will make direct use of the microlayer. Principal component analysis (PCA) of PAHs indicated the important contribution of traffic engine emission in the particulate samples of the SML and SSW and revealed that probably the petroleum pollutants are a predominant source for the dissolved phase. Cluster analysis revealed that PAH-PCB patterns in the river and anchorage channels were different to those in the wetlands and open harbor. However, PCA of PCBs showed differences in the congener profiles for the two phases, with highly chlorinated PCBs more abundant in particles, while less chlorinated PCBs were more abundant in dissolved.

Simulating the spatiotemporal distribution of BTEX with an hourly grid-scale model.

Modeling approaches have been utilized to simulate ambient pollutant concentrations, but very limited efforts have been made to estimate volatile organic compounds in the atmosphere. For this reason, an hourly grid-scale simulation model was developed to determine ambient air concentrations of benzene, toluene, ethylbenzene, and xylene (BTEX). BTEX data were collected over a one-year time frame from the database of the Taiwan Environmental Protection Administration's photochemical assessment monitoring stations. Multivariate linear regression models were used along with correlation analysis to simulate hourly grid-scale BTEX concentrations, using criteria pollutants and selected meteorological variables as predictors. The simulation model was validated in the southern Taiwan area via a portable micro gas chromatography system (n = 121) with significant correlation (r = 0.566**, ** indicated p < 0.01). Moreover, the grid-scale model was applied to areas covering about 72% of the population in Taiwan. A geographic information system (GIS) was used to visualize the spatial distribution of BTEX concentrations from the modeling results. This new grid-scale modeling strategy, which incorporated the GIS output of the simulated data, provides a useful alternative tool for personal exposure analysis and health risk assessment of ambient air BTEX.

Differential time-lag effects of ambient PM2.5 and PM2.5-bound PAHs on asthma emergency department visits.

Epidemiological studies have suggested the effects of ambient fine particles (PM2.5) on asthma, but the effects of specific components of PM2.5 on asthma remain to be explored. Here, we studied the effect of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) on asthma acute exacerbation. The data on daily counts of emergency room visits (ERVs) were obtained from Wan Fang Medical Center, Taipei, Taiwan, from 2012 to 2015. The daily concentrations of PM2.5 and pollutant gases were obtained from a local air quality monitoring station. The levels of PM2.5-bound PAH were estimated by an established grid-scale model. Relative risks for ERVs as the increase in the level of ambient pollutants were calculated by using a generalized additive model of Poisson regression. In the present study, we observed statistically significant positive associations between PM2.5 and asthma ERVs for all age groups. PM2.5-bound PAH was also associated with asthma ERVs for all age groups. In the adult subgroup analysis, there was a significant association between PM2.5-bound PAH and asthma ERVs at lags 1 and 2 (RR 1.289, 95% CI 1.050-1.582 and RR 1.242, 95% CI 1.039-1.485). The impacts of air pollution on the risk of pediatric asthma ERV were found to be significant for PM2.5 at lag day 0 (RR 1.310, 95% CI 1.069-1.606). Moreover, pediatric asthma ERVs were significantly associated with the levels of PM2.5-bound PAH at lag 1 and 2 days (RR 1.576, 95% CI 1.371-1.810 and RR 1.426, 95% CI 1.265-1.607). The study provides evidence that PM2.5-bound PAHs were associated with an increased risk of asthma attacks. Our data further suggested that traffic exhaust is a primary source of PM2.5-bound PAHs.