Particle-bound Particle-bound Polycyclic Aromatic Hydrocarbons Research Articles

Spatial distribution, driving factors and health risks of fine particle-bound polycyclic aromatic hydrocarbons (PAHs) from indoors and outdoors in Hefei, China

Atmospheric particulate matter, especially in urban and industrial environments, can act as a source of different organic pollutants that can pose significant health impacts to residents. However, the pollution status and transport mechanisms of fine particle-bound polycyclic aromatic hydrocarbons (PAHs) in indoor and outdoor environments are uncertain. This study aimed to determine the spatial distribution and morphological characteristics of fine particle-bound PAHs and analyze the factors (source contributions and backward trajectories) that influence their concentrations. The results showed that mean concentrations of 16 PAHs were higher in indoor dust as compared to outdoor dust. In addition, the lowest concentrations of the 16 PAHs were found on the 11-20th floor, with smoking households > nonsmoking households (except Nap, Acy, and Ace). The 2–3 ring PAHs were more prominent in households with cooking activities. The particle size distribution showed that most of the particles were <62 μm in diameter, indicating that the indoor particles were smaller in size. Furthermore, the range of δ13C values in the outdoor dust (−30.17 ~ −28.63 ‰) samples was significantly lower than in indoor dust (−28.29 ~ −22.53 ‰). The results based on diagnostic ratios, positive matrix factorization (PMF) analysis and backward trajectory model analysis suggested that the sources of PAHs in indoor and outdoor dust were mixed, originated both locally and from neighboring provinces transported over long distances, especially concentrated in the Yangtze River Delta area. Finally, carcinogenic risk values for indoor dust were greater than those for outdoor dust. Therefore, it is recommended that local governments and industries with high PAH emissions should implement proper protocols to monitor and minimize the pollution levels of PAHs in the urban industrial environment in order to mitigate their health risks.

Characterizing Real-World Particle-Bound Polycyclic Aromatic Hydrocarbon Emissions from Diesel-Fueled Construction Machines

This study employed an onboard emission measurement system to measure the real-world emission factors of particulate matter (PM), particle-bound polycyclic aromatic hydrocarbons (PAHs), and gaseous air pollutants for different types of diesel-fueled non-road construction machines operated inside confined spaces within a brick manufacturing factory located in Taiwan. To the best knowledge of the authors, this is the first study that reports real-world PM, PAH, and gaseous pollutant emission factors for non-road engines in Taiwan. The mean real-world fuel-specific emission factors of PM, carbon monoxide, total hydrocarbons, and nitric oxide were 0.712–1.17, 8.27–17.9, 3.04–5.77, and 38.1–96.8 g/kg-fuel, respectively, for the test machines. Likewise, mean ΣPAHs emission factors ranged from 157 to 230 μg/kg-fuel for three types of test machines. Further, the average emission of particle-bound PAH per unit PM emission ranged from 213 to 384 μg-PAH/g-PM. Among the analyzed PAHs, the medium-molecular weight (3- and 4-ring) compounds contributed to the largest share of particle-bound PAH emissions. However, in terms of Benzo[a]pyrene equivalent (BaPeq) toxicity, the high-molecular weight (5- and 6-ring) PAHs were more important, as they had the highest BaPeq toxic emission factors. This study provides detailed composition and emission factors of particle-bound PAHs in non-road diesel construction machine emissions, which may be useful as a chemical fingerprint for source apportionment studies.

Polycyclic aromatic hydrocarbons from cooking emissions

Air pollution studies have often overlooked the contribution from cooking to the particle-bound polycyclic aromatic hydrocarbons (PAHs) in the ambient environment, despite cooking emissions have been identified as an important source of organic aerosol in most urban areas, known as the cooking-like organic aerosol factor (i.e., COA). In this study, a Long-Time-of-Flight (LToF) soot particle aerosol mass spectrometer (SP-AMS) was deployed to evaluate the impact of cooking emissions on outdoor particle-bound PAHs levels during a summer campaign in 2019 in Xi'an China. Combined with the robust receptor model, cooking emission was found to be the major source of ambient PAHs, on average, accounting for 90% of PAHs, 9 times higher than traffic (10%). The ambient cooking PAH profile was well correlated (r2 of 0.87) with that for frying oil fume, suggesting cooking oil was the major source of PAHs instead of the food being cooked. We further evaluated the health risk associated with the cooking PAHs and estimated the cooking PAH levels in some of the major cities in the world where COA factor has been reported. The results show the particle-bound PAHs from cooking can be an important source of ambient PAHs in most Chinese cities. The findings from this study hold important implications for public health and are informing for policymakers.

Particle-bound PAHs induced glucose metabolism disorders through HIF-1 pathway

Vehicle exhaust, as one of the most important compositions of air pollution, induced various adverse health effects, especially diabetes, on human beings. Even though monitoring and epidemiological data indicates that particle-bound polycyclic aromatic hydrocarbons (PAHs) is an inducing factor of diabetes, the specific causative mechanisms are still unclear. In the current study, the concentration of particulate matters (PMs, including PM1.0, PM2.5 and PM10.0) and PAHs was investigated at rush hour of weekday in three urban underground parking garages (UPGs). To evaluate the impacts of particle-bound PAHs on human beings, analysis of non-target metabolomics and unmetabolized PAHs were conducted for UPG and non-UPG worker urine samples. The results showed that the highest concentrations of PMs and total PAHs were found at the UPG entrance. The concentrations of unmetabolized 5-6 rings PAHs in the UPG worker urine were significantly higher than that in non-UPG worker urine samples, which induced glucose metabolism disorders through hypoxia-inducible factor 1 (HIF-1) signaling pathway. This could be a reason for particle-bound PAHs induced-diabetes on road workers, drivers and garage staff. These findings can serve as a step towards air pollution management and the pathological mechanism analysis of environmental factor induced-diseases.

Effects of driving behavior on real-world emissions of particulate matter, gaseous pollutants and particle-bound PAHs for diesel trucks

This study employed a portable emissions measurement system to investigate the effects of vehicle attributes, driving behavior, and road grade on real-world emissions of particulate matter (PM), regulated gaseous pollutants, and particle-bound polycyclic aromatic hydrocarbons (PAHs) for old-model diesel trucks (model year 1995–2006, 6.7–35.0 metric ton) with little to no tailpipe emission control. The rated power of engines was a major determinant of the distance-specific emission factors of PM, particle-bound PAHs, and most gaseous pollutants. However, the engine size was unrelated to the total hydrocarbon emission factor and the benzo[a]pyrene equivalent (BaPeq) emission factor of PAHs. Aggressive (AG) and normal (NR) driving behaviors were quantitatively defined with a relative positive acceleration. The emission factors of PM, CO2, and THC were significantly different (p < 0.05) between the AG and NR driving modes. AG driving caused an average increase in emissions of PM, CO2, NOx, and particle-bound PAHs by 122%, 56%, 15%, and 128%, respectively, compared to the respective emissions under the NR mode. The BaPeq emission factor of PAHs in the AG mode was more than 10 times that in the NR mode. The road gradient (ranging from −9.3% to 9.0% over the test route) had significant impacts on the emissions of PM, CO2, and NOx. PM, CO2, and NOx emission factors increased by 109%, 168%, and 160%, respectively, in the >6% grade bin and decreased by 95%, 91%, and 90%, respectively, in the equivalent negative-grade bin, implying that the decrease in emissions on negative road slopes may not compensate for the increase in emissions on the equivalent positive road slopes despite the road slope being compensated. The findings of this study will be valuable for developing air quality management strategies and furthering scientific knowledge on the complex interplay of different variables that affect real-world emissions of on-road vehicles.

Particle-bound PAHs and Chemical Composition, Sources and Health Risk of PM2.5 in a Highly Industrialized Area

PM2.5 monitoring campaigns were conducted in 2006, 2010, and 2011 in Tula, Hidalgo, Mexico, a highly industrialized area which includes a refinery, a thermoelectric power plant, five cement plants, limestone mining, and industrial waste combustion. These data establish baselines and trends against which later concentrations can be compared as emission reduction plans are implemented. PM2.5 mass, chemical composition, and 15 particle-bound polycyclic aromatic hydrocarbons (PAHs) were measured at two sites. PM2.5 masses ranged from 26 to 31 µg m–3. Carbonaceous aerosols were the largest PM2.5 component, accounting for 47–57% of the mass. Approximately 40–51% of the carbonaceous aerosol was attributed to secondary organic carbon. Ionic species accounted for 40–44% of PM2.5, with sulfate being the dominant ion. The sum of particle-bound PAH concentrations ranged from 14–31 ng m–3. Six factors derived from Principal Component Analysis (PCA) explained ~85% of the PM2.5 variance. The derived factors were associated with sources based on marker species resulting in heavy-oil combustion (22% of variance), vehicle engine exhaust (13–19% of variance), fugitive dust (18% of variance), biomass burning (9–13% of variance), secondary aerosols (14% of variance), and industrial emissions (6–10% of variance). Combustion of solid waste (e.g., tires and industrial waste) of the recycling cement kilns and incinerators resulted in elevated toxic species such as, Cd, and Sb in the range of 0.02–0.3 µg m–3. A health risk assessment of carcinogenic trace elements was performed showing that the total cancer risk decreased for both children and adults in 2010/2011 (ranging from 3.5 × 10–6 to 6.0 × 10–5) as compared to 2006 (ranging from 8.6 × 10–7 to 5.7 × 10–6). The inhalation life-time cancer risk (ILCR) for particle-bound PAHs ranged from 8.6 × 10–5 to 1.2 × 10–4. Air quality can be improved by switching to cleaner fuels and benefit from the use of natural gas instead of fuel oil in the power plant.

Dermal exposure to particle-bound polycyclic aromatic hydrocarbons from barbecue fume as impacted by physicochemical conditions

Inhalation of size-dependent particle-bound polycyclic aromatic hydrocarbons (PAHs) has been extensively studied, whereas dermal absorption has not been adequately investigated. To address this knowledge gap, dermal absorption of size-dependent particle-bound PAHs was characterized through the collection of indoor air and forearm wipe samples in the setting of an indoor barbecue. The mass of size-fractioned PAHs associated with particulate matter was greater in fine particles (<1.8 μm) than in coarse particles (>1.8 μm). Gas-particle distribution of specific PAHs from barbecue fume was ascribed to both adsorption and absorption which would probably be close to equilibrium, while that from background air was dominated by absorption. Forearm-deposited amounts of particulate PAHs suggested that removal of coarse and fine particles could minimize exposure to low and high molecular-weight (MW) PAHs, respectively. Besides, the concentrations of particulate PAHs in forearms wipe were significantly correlated to their dry deposition fluxes with coarse particles, but weakly correlated to those with fine particles. This indicated that particle size would influence dermal absorption efficiency of particle-bound PAHs with fine particles prolonging dermal exposure to PAHs. Overall, higher MW particle-bound PAHs derived from barbecue fume may pose higher risk to human health by dermal absorption than lower MW PAHs.

Characterization of Residential Woodsmoke PM2.5 in the Adirondacks of New York

ABSTRACT Although woodsmoke from residential wood heating can be the dominant source of winter PM2.5 in rural areas, routine monitoring is done primarily in urban or suburban areas. To obtain data on elevated woodsmoke concentrations from nearby sources, the PM2.5, black carbon at 880 and 370 nm, particle-bound polycyclic aromatic hydrocarbons (PAHs), and wind speed and direction were measured during winter at three residential locations in Saranac Lake, New York. A paired-site design enabled the identification of local sources relative to larger spatial scales. With the exception of occasional regional PM events, the hourly measurements of this pollutant between the paired sites exhibited poor correlations, suggesting that local woodsmoke was responsible for the observed increases in PM values. One location that was adjacent to a residence with a wood stove, which was 40 meters from the monitoring site, experienced repeated episodes of elevated PM2.5 concentrations, with a maximum 3-hour average of 150 µg m–3, a maximum 24-hour rolling average of 64 µg m–3, and a maximum midnight-to-midnight average of 46 µg m–3. Despite these PM events, the data indicated that this location was likely in compliance with the current U.S. EPA National Ambient Air Quality Standards (NAAQS) for PM2.5. The daily PM2.5 concentration peaked and troughed during the nighttime and the daytime, respectively, at all of the sites, which is consistent with local ground-level pollution sources, such as woodsmoke; this diel pattern was also confirmed by Aaethalometer Delta-C (DC) data, a woodsmoke PM indicator. The particle-bound PAH data was less specific than the DC data to the PM in the woodsmoke, partly because the instrument for the former also responds to traffic pollution. One site repeatedly displayed the influence of 2-cycle engine snowmobile exhaust during the early evening hours, with very high PAH concentrations but only modestly elevated DC concentrations. Subsequent tests showed that fresh 2-cycle small engine exhaust produces a somewhat weaker response than woodsmoke in the DC in terms of the concentration per unit of PM.

Particulate Matter and Particle-Bound PAHs Emissions from Gasoline Direct Injection (GDI) Engine with Methanol-Gasoline Blended Fuel During Start

The effects of coolant’s temperature on emissions of particulate matters (PM) and particle-bound polycyclic aromatic hydrocarbons (PAHs) from a gasoline direct injection (GDI) engine were studied during the start process using gasoline (M0) and gasoline mixed with methanol in 15 % volume (M15). The engine worked at a certain idle speed automatically under different coolant’s temperature conditions after successful start. The experimental data was recorded from 0 to 40 seconds during the start. Results indicated that, there are significant differences in PM and particle-bound PAHs emissions between cold and warm start conditions. Particulate size distribution was measured with the Engine Exhaust Particle Sizer (EEPS) 3090. Compared with M0 fuel, the PM emission of M15 fuel decreased significantly, especially nucleation-mode particulate emission. The mass emission of PM was measured using the Gravimetric method. A same variation trend in PM mass emissions can be inferred for both fuels, i.e. it decreases while the coolant’s temperature increases. Compared with M0 fuel, the PM mass with M15 fuel reduces by 80 % at 20 oC coolant’s temperature. Agilent 7000B GC-QQQ was used to provide both qualitative and quantitative analysis on PAHs. The application of M15 fuel reduces the concentrations of most PAH species compared with M0 fuel, except those with smaller aromatic rings. In addition, Benzo(a)pyrene equivalent toxicity (BEQ) is calculated to evaluate the toxicity of PAHs emissions. The toxicity decreases when the GDI engine starts with higher coolant’s temperature or with M15 fuel.

Determination of particle-bound polycyclic aromatic hydrocarbons emitted from co-pelletization combustion of lignite and rubber wood sawdust

Determination of particle-bound Polycyclic Aromatic Hydrocarbons (PAHs) emitted from co-pelletization combustion of lignite and rubber wood sawdust in a horizontal tube furnace is investigated using High Performance Liquid Chromatography with coupled Diode Array and Fluorescence Detection (HPLC-DAD/FLD). The particle-bound PAHs based on the mass concentration and the toxicity degree are discussed in the different size ranges of the particulate matters from 0.07-11 μm. In the present study, the particle-bound PAHs are likely abundant in the fine particles. More than 70% of toxicity degree of PAHs falls into PM1.1 while more than 80% of mass concentration of PAHs falls into PM2.5. The addition of lignite amount in the co-pelletization results in the increasing concentration of either 4-6 aromatic ring PAHs or high molecular weight PAHs. The high contribution of 4-6 aromatic ring PAHs or high molecular weight PAHs in the fine particles should be paid much more attention because of high probability of human carcinogenic. Furthermore, the rubber wood sawdust pellets emit high mass concentration of PAHs whereas the lignite pellets emit high toxicity degree of PAHs. By co-pelletized rubber wood sawdust with lignite (50% lignite pellets) has significant effect to reduce the toxicity degree of PAHs by 70%.

Characterization of particulate-phase polycyclic aromatic hydrocarbons emitted from incense burning and their bioreactivity in RAW264.7 macrophage

This study investigated the effects of particle-bound polycyclic aromatic hydrocarbons (PAHs) produced from burning three incense types on and their bioreactivity in the RAW 264.7 murine macrophage cell line. Gas chromatography/mass spectrometry was used to determine the levels of 16 identified PAHs. Macrophages were exposed to incense particle extracts at concentrations of 0, 3.125, 6.25, 12.5, 25, 50, and 100 μg/mL for 24 h. After exposure, cell viability and nitric oxide (NO) and inflammatory mediator [tumor necrosis factor (TNF)-α] production of the cells were examined. The mean atomic hydrogen (H) to carbon (C) ratios in the environmentally friendly, binchotan charcoal, and lao shan incenses were 0.69, 1.13, and 1.71, respectively. PAH and total toxic equivalent (TEQ) mass fraction in the incenses ranged from 137.84 to 231.00 and 6.73–26.30 pg/μg, respectively. The exposure of RAW 264.7 macrophages to incense particles significantly increased TNF-α and NO production and reduced cell viability. The cells treated with particles collected from smoldering the environmentally friendly incense produced more NO and TNF-α compared to other incenses. Additionally, the TEQ of fluoranthene (FL), pyrene (Pyr), benzo[a]anthracene (BaA), chrysene (Chr), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1,2,3-cd]pyrene (INP), dibenz[a,h]anthracene (DBA), and benzo[g,h,i]perylene [B(ghi)P] had a significant correlation (R2 = 0.64–0.98, P < 0.05) with NO and TNF-α production. The current findings indicate that incense particle-bound PAHs are biologically active and that burning an incense with a lower H/C ratio caused higher bioreactivity. The stimulatory effect of PAH-containing particles on molecular mechanisms of inflammation are critical for future study.

Turbulent transport of particle-bound PAHs: A feasibility study combining GC-APLI-MS and eddy covariance

A novel approach combining gas chromatography-atmospheric pressure laser ionization-time-of-flight-mass spectrometry (GC-APLI-MS) with the micrometeorological eddy covariance (EC) technique is demonstrated to quantify particle-bound polycyclic aromatic hydrocarbons (PAH) mass fluxes above a central European city. During the case study, 18 different PAH compounds could be identified in two one-hour particle samples and, in combination with size-resolved particle deposition velocities obtained from EC measurements, inferred particulate PAH mass fluxes for two respective size fractions (0.060–0.108 μm and 0.170–10 μm) were quantified. Maximum concentrations and fluxes (in the order of 0.9 ± 0.09–17 ± 8 ng m−2 hr−1) were estimated for the 5-ring PAHs benzo[e]pyrene, benzo[a]pyrene and perylene. Fingerprints of PAH concentrations suggest strong pyrogenic sources, particularly wood burning.

Influence of wind direction and speed on the transport of particle-bound PAHs in a roadway environment

The influence of wind direction and speed on the transport of vehicular air pollutants was investigated using a mobile laboratory in an urban area. We considered three spatial scales covering typical transport phenomena observed in urban areas: micro-scale (a few tens of meters), middle-scale (a few hundred meters) and neighborhood-scale (a few kilometers). Particle-bound polycyclic aromatic hydrocarbons (PAHs) were selected as an indicator of vehicle emissions in the roadway environment. From the micro-scale measurements, we found a significant difference in the concentration of particle-bound PAHs within a small spatial area, on a two-way road, due to the effect of wind direction when the prevailing wind direction was constant. In the middle-scale experiments, an exponential decrease in the concentration of particle-bound PAHs was observed with distance from the intersection in the direction of the prevailing wind, which is consistent with the results of previous studies. The concentration of particle-bound PAHs near the road was ∼10 times higher than that at 200 m away from the road due to the significantly low background concentration, indicating that particle-bound PAHs are a good indicator of vehicle emissions in a roadway environment. From long-distance (∼15 km) traveling measurements made over 14 days, we found that the average concentration of particle-bound PAHs on the road decreased as the prevailing wind speed increased at the neighborhood-scale, when the wind speed was higher than 2.0 m/s. This analysis, over three spatial scales, will be helpful in understanding the effect of wind on air pollution in a roadway environment in urban areas.

Characteristics of nanoparticles emitted from burning of biomass fuels

The characteristics of the particles of the smoke that is emitted from the burning of biomass fuels were experimentally investigated using a laboratory-scale tube furnace and different types of biomass fuels: rubber wood, whole wood pellets and rice husks. Emitted amounts of particles, particle-bound polycyclic aromatic hydrocarbons (PAHs) and water-soluble organic carbon (WSOC) are discussed relative to the size of the emitted particles, ranging to as small as nano-size (<70nm), and to the rate of heating rate during combustion. differential thermal analysis (DTA) and thermogravimetric analysis (TG) techniques were used to examine the effect of heating rate and biomass type on combustion behaviors relative to the characteristics of particle emissions. In the present study, more than 30% of the smoke particles from the burning of biomass fuel had a mass that fell within a range of <100nm. Particles smaller than 0.43μm contributed greatly to the total levels of toxic PAHs and WSOC. The properties of these particles were influenced by the fuel component, the combustion conditions, and the particle size. Although TG–DTA results indicated that the heating rate in a range of 10–20°C did not show a significant effect on the combustion properties, there was a slight increase in the decomposition temperature as heating rate was increased. The nano-size particles had the smallest fraction of particle mass and particle-bound PAHs, but nonetheless these particles registered the largest fraction of particle-bound WSOC.

Emission and size distribution of particle-bound polycyclic aromatic hydrocarbons from residential wood combustion in rural China

Emissions and size distributions of 28 particle-bound polycyclic aromatic hydrocarbons (PAHs) from residential combustion of 19 fuels in a domestic cooking stove in rural China were studied. Measured emission factors of total particle-bound PAHs were 1.79 ± 1.55, 12.1 ± 9.1, and 5.36 ± 4.46 mg kg−1 for fuel wood, brushwood, and bamboo, respectively. Approximate 86.7, 65.0, and 79.7% of the PAHs were associated with fine particulate matter with size less than 2.1 μm for these three types of fuels, respectively. Statistically significant differences in emission factors and size distributions of particle-bound PAHs between fuel wood and brushwood were observed, with the former had lower emission factors but more PAHs in finer PM. Mass fraction of the fine particles associated PAHs was found to be positively correlated with fuel density and moisture, and negatively correlated with combustion efficiency. Low and high molecular weight PAHs preferably segregated into the coarse and fine PM, respectively. The high accumulation tendency of the PAHs from residential wood combustion in fine particles implies strong adverse health impact.

Measurements of Ultrafine Particles and Other Vehicular Pollutants inside a Mobile Exposure System on Los Angeles Freeways

A mobile exposure and air pollution measurement system was developed and used for on-freeway ultrafine particle health effects studies. A nine-passenger van was modified with a high-efficiency particulate air (HEPA) filtration system that can deliver filtered or unfiltered air to an exposure chamber inside the van. State-of-the-art instruments were used to measure concentration and size distribution of fine and ultrafine particles and the concentration of carbon monoxide (CO), black carbon (BC), particle-bound polycyclic aromatic hydrocarbons (PAHs), fine particulate matter (PM2.5) mass, and oxides of nitrogen (NOx) inside the exposure chamber. This paper presents the construction and technical details of the van and air pollutant concentrations collected in 32 2-hr runs on two major Los Angeles freeways, Interstate 405 (I-405; mostly gasoline traffic) and Interstate 710 (I-710; large proportion of heavy-duty diesel traffic). More than 97% of particles were removed when the flow through the filter box was switched from bypass mode to filter mode while the vehicle was driving on both freeways. The filtration system thus provides a great particulate matter exposure contrast while keeping gas-phase pollutant concentrations the same. Under bypass mode, average total particle number concentration observed inside the exposure chamber was around 8.4 × 104 and 1.3 × 105 particles cm-3 on the I-405 and the I-710 freeways, respectively. Bimodal size distributions were consistent and similar for both freeways with the first mode around 16–20 nm and the second mode around 50–55 nm. BC and particle-bound PAH concentrations were more than two times greater on the I-710 than on the I-405 freeway. Very weak correlations were observed between total particle number concentrations and other vehicular pollutants on the freeways.

A Space/Time Particulate Matter Mass Fraction Framework for the Assessment of Outdoor Exposure to Polycyclic Aromatic Hydrocarbons After 9/11 in New York City

P-061 Introduction: Recent papers indicate that Particle-bound Polycyclic Aromatic Hydrocarbons (PAHs) may have adverse effects on birth outcomes. A recently developed method is available for analyzing the concentration of PAHs in archived PM2.5 samples. Using the expansive PM2.5 monitoring network available, this work proposes a space/time estimation method for the exposure assessment of atmospheric PAH where PM2.5 data are available, with a few re-analyzed for PAHs. This method is tested and implemented using data collected after 9/11 around the World Trade Center site. Methods: Nine particle-bound PAHs: benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, dibenzo(a,h)anthracene, benzo(g,h,i)perylene, and benzo(e)pyrene were measured in archived PM2.5 samples at four locations around Ground Zero from September 22, 2001 until March 27, 2002. The EPA AIRS monitoring system regularly collected PM2.5 data during this time period across the entire New York/New Jersey area. Using the small subset of archived PM2.5 samples that were re-analysed for PAHs, we developed a non-parametric, probabilistic model predicting the PAH mass fraction in the neighbourhood of the WTC. This model is used at remaining PM2.5 samples to obtain soft PAH data. Bayesian Maximum Entropy data integration of the few directly measured PAH data with the more numerous soft data was performed to obtain an assessment of the population exposure to PAHs after 9/11. Results: Even with the limited spatial domain of available PAH data and a mass fraction created only as a function of time, a spatial validation showed the addition of PAH data derived from PM2.5 reduced the mean squared error from 7–22%. Since the maximum spatial distance available for validation was small, the MSE reduction should only improve at greater distances. Temporally, there was an exponential improvement in MSE positively associated with the number of days of PAH data removed. Discussion/Conclusions: PAH compounds were elevated in New York after 9/11 due to burning jet fuel, the towers' collapse and ensuing fires, diesel equipment used in the clean-up process, and the background concentrations already present. Our results provide the first maps using a mass fraction approach to obtain an assessment of the space/time exposure of the population to atmospheric PAHs after 9/11. These maps show the highest cumulated PAH exposure to be southwest of the WTC site, but with its high population density, the largest effect should be in eastern lower Manhattan. The mass fraction approach combined with optimal PAH sampling looks promising as an exposure index for future PAH research.

Modelling of runoff behaviour of particle-bound polycyclic aromatic hydrocarbons (PAHs) from roads and roofs

Road and roof dust was collected and samples of runoff were taken at an urban storm sewer system in a residential area in Japan. Suspended solids (SS) in the runoff samples were classified into two fractions: fine (smaller than 45 microm) and coarse (larger than 45 microm). Runoff monitoring and chemical analysis data were also used to validate a runoff model for particle-bound polycyclic aromatic hydrocarbons (PAHs) that was originally developed to explain the behaviour of SS in the same area. The model, in which roads and roofs were considered separately as impervious surfaces, expressed the SS and particle-bound PAHs runoff behaviour for fine and coarse particles very well, except during and after heavy rainfalls (more than 10mm/h). However, the model could not explain the PAH profiles of runoff particles; the profiles of 12 PAH compounds tracked in this study were almost constant and more similar to those of road dust than roof dust throughout the event. An improved model is developed which explains the runoff behaviour by considering two types of road dust with different mobility.

Influence of traffic patterns on particulate matter and polycyclic aromatic hydrocarbon concentrations in Roxbury, Massachusetts

Vehicle emissions have been associated with adverse health effects in multiple epidemiological studies, but the sources or constituents responsible have not been established. Characterization of vehicle-related exposures requires detailed information on spatial and temporal trends of various pollutants and the ability to predict exposures in unmonitored settings. To address these issues, in the summer of 2001 we measured continuously particle-bound polycyclic aromatic hydrocarbons (PAHs), ultrafine particles, and PM(2.5) at a number of sites in Roxbury, a neighborhood of Boston, Massachusetts with significant diesel and gasoline-fueled traffic. We took measurements at the side of the road and at varying distances from the road, with simultaneous collection of traffic counts and meteorological conditions. Across all nine sites, median roadside concentrations were 8 ng/m(3) of particle-bound PAHs (range: 4-57), 16,000 ultrafine particles/cm(3) (range: 11,000-53,000), and 54 microg/m(3) of PM(2.5) as measured with a DustTrak (range: 12-86). Concentrations of all pollutants were lower at greater distances from the road, upwind, and at higher wind speeds, with greater concentration gradients for PAHs and ultrafine particles. In linear mixed effects regression models accounting for temporal autocorrelation, large diesel vehicle counts were significantly associated with roadside concentrations of PAHs (P=0.02), with a moderate association with ultrafine particles and little relation with PM(2.5). Although more comprehensive information would be needed for epidemiological applications, these data demonstrate significant spatial and temporal heterogeneity for traffic-related pollutants during the summer in an urban center, with our monitoring and analytical methodology helping to inform source attribution.

Polycyclic aromatic hydrocarbons in the ambient air of suburban and industrial regions of central Taiwan

The concentrations of gas-phase and particle-bound polycyclic aromatic hydrocarbons (PAHs) were measured simultaneously at an industrial area (Taichung Industrial Park) and a suburban area (Tunghai University Campus) in Taichung, Taiwan. Twenty-four hours samplings for two consecutive days were performed between August and December 2002 at both sampling sites. Ambient air particle-bound PAHs were collected on quartz filters and gas-phase PAHs were collected on glass cartridges using a PUF Sampler, respectively. Both types of samples were extracted with a DCM/ n-hexane mixture (50/50, v/v) for 24 h, then the extracts were subjected to gas chromatography–mass spectrometric (GC–MS) analysis. Total PAHs concentrations at the Taichung Industrial Park (TIP) sampling site and the Tunghai University Campus (THUC) sampling site were found to be 1232.3 ± 963.6 and 609.8 ± 356.3 ng/m 3, respectively. Stationary combustion processes were mainly responsible for PAHs sources at the TIP sampling site, while traffic vehicle exhaust was the largest contributor for PAHs sources at the THUC sampling site.