Vapor Phase Polycyclic Aromatic Hydrocarbons Research Articles

Wildfire Impact on Indoor and Outdoor PAH Air Quality.

Air quality impacts from wildfires are poorly understood, particularly indoors. As frequencies increase, it is important to optimize methodologies to understand and reduce chemical exposures from wildfires. Public health recommendations use air quality estimates from outdoor stationary air monitors, discounting indoor air conditions, and do not consider chemicals in the vapor phase, known to elicit adverse effects. We investigated vapor-phase polycyclic aromatic hydrocarbons (PAHs) in indoor and outdoor air before, during, and after wildfires using a community-engaged research approach. Paired passive air samplers were deployed at 15 locations across four states. Twelve unique PAHs were detected only in outdoor air during wildfires, highlighting a PAH exposure mixture for future study. Heavy-molecular-weight (HMW) outdoor PAH concentrations and average Air Quality Index (AQI) values were positively correlated (p < 0.001). Indoor PAH concentrations were higher in 77% of samples across all sampling events. Even during wildfires, 58% of sampled locations still had higher indoor PAH air concentrations. When AQI values exceeded 140 (unhealthy for sensitive groups), outdoor PAH concentrations became similar to or higher than indoors. Cancer and noncancer inhalation risk estimates from vapor-phase PAHs were higher indoors than outdoors, regardless of the wildfire impact. Consideration of indoor air quality and vapor-phase PAHs could inform public health recommendations regarding wildfires.

Evergreen or deciduous trees for capturing PAHs from ambient air? A case study

Tree canopies play a key role in the cycling of polycyclic aromatic hydrocarbons (PAHs) in terrestrial ecosystems, as leaves can capture PAHs from the air. In this study, accumulation of PAHs was compared in an evergreen species, P. pinaster, and in a deciduous species, Q. robur, in relation to some physio-morphological characteristics. For this purpose, pine needles and oak leaves collected from different sites across Galicia (NW Spain) were analysed to determine PAH contents, specific leaf area, stomatal density and conductance.Leaves and needles contained similar total amounts of PAHs. The major contribution of particle-bound PAHs in oak (the concentrations of 4- and 5-ring PAHs were two times higher, and those of 6-ring PAHs five times higher in oak than in pine) may be related to the higher specific leaf area (13 and 4 cm2 g−1 dry mass in respectively oak and pine). However, the major contribution of vapor-phase PAHs in pines may be affected by the stomatal conductance (two times higher in pine than in oak). Moreover, an increase in the diameter at breast height of trees led to an increase in accumulation of PAHs, with pine capturing higher amounts of low and medium molecular weight PAHs. The study findings underline the potential role of trees in improving air quality, taking into account the canopy biomass and life cycle.

Development of a soot particle model with PAHs as precursors through simulations and experiments

In the present study, the polycyclic aromatic hydrocarbons (PAHs) and soot particulates emitted from a gasoline direct injection (GDI) engine were sampled and analyzed. The results show that the vapor-phase PAHs and particulate-bound PAHs exist in GDI engine exhaust emissions. Soot particles are formed by the agglomeration of the quasi-spherical primary carbon particles, and the size of the PAH cluster is close to that of the core of the primary carbon particles. To predict soot particulates evolution in the engine cylinder, a reduced toluene reference fuel (TRF)-PAH chemical mechanism consisting of iso-octane, n-heptane and toluene as gasoline surrogate fuels for the GDI engine combustion simulation was developed. The reduced mechanism contains 232 reactions and 85 species, including 17 species and 40 elementary reactions, related to the PAH formation, which could well capture the oxidation characteristics of ignition delays and laminar flame speeds, as well as PAH emissions from the GDI engine. Then, a mathematical soot growth model coupled with the reduced TRF-PAH mechanism was developed based on the method of moment. The obtained experimental soot emissions were well predicted by this soot model. The distribution of particle number density was consistent with the distribution of A4 and C2H2, and the growth and distribution of soot mass was determined by the particle surface growth due to C2H2, the nuclear reaction of A4 and the particle surface oxidation reaction.

Gas-Phase Polycyclic Aromatic Hydrocarbons in the Parking Lot Impacted by Light-Duty Vehicles Burning Gasoline and Ethanol Blends

In order to study the emission of vapor-phase polycyclic aromatic hydrocarbons (PAHs) by light-duty vehicles burning gasoline and ethanol blends, air samplings were performed at a parking lot in Londrina, PR, Brazil. The samples were obtained during the summer and winter 2012. The semi-volatile PAHs were collected using a cartridge packed with XAD-2 resin, extracted under sonication and subsequently analyzed by liquid chromatograph equipped with fluorescence and photodiode array detectors. Acenapthene (ACE) appears as the most abundant PAH, followed by acenapthylene (ACY) (summer) and fluorene (FLU) (winter). From the total PAHs analyzed (83.5 ng m−3 in winter and 574 ng m−3 in summer), low molecular weight PAHs (LM-PAHs) corresponded to 93%. The PAH source fingerprint identified in this study was obtained from local and identified sources, and the fluoranthene (FLT) / (FLT + pyrene (PYR)) and anthracene (ANT) / (ANT + phenanthrene (PHE)) ratios corresponding to 0.94 and 0.46, respectively, were characteristic of gasoline and ethanol blend emission.

An experimental study of polycyclic aromatic hydrocarbons and soot emissions from a GDI engine fueled with commercial gasoline

This study investigated the chemical characteristics of polycyclic aromatic hydrocarbons (PAHs) and soot particulates emitted from a gasoline direct injection (GDI) engine. The microcosmic morphology of the soot particulate and the correlations between PAH species and the primary carbon particles were studied during dynamometer testing of different engine operating conditions using our purpose-built sampling system. The obtained extracts of PAH samplings and soot samplings were analyzed qualitatively and quantitatively using gas chromatograph–mass spectrometry (GC–MS) and field-emission transmission electron microscopy (FE-TEM). The vapor-phase and particulate-bound PAHs exist in the GDI engine exhaust emissions. PAHs with two and three rings exist nearly entirely in the gas phase, whereas five or more fused rings are predominantly adsorbed on soot particles. The intermediate 4-ring PAHs exist in the two PAH phase. Naphthalene is the most abundant polyaromatic hydrocarbon that was detected in the exhaust vapor-phase PAHs, which was approximately three orders of magnitude higher than the PAHs in the particulate phase. PAHs and soot emissions could be significantly reduced by increasing the injection pressure and by introducing the exhaust gas into the cylinders. Particulate-bound PAHs A4–A6 were suitable for estimating soot emissions from GDI engines. Soot particles are formed by the agglomeration of the quasi-sphere primary carbon particles. Most of the primary carbon particles exhibit an onion-shell nanostructure, with less disordered and amorphous structures.

Characterization of particulate and vapor phase polycyclic aromatic hydrocarbons in indoor and outdoor air of primary schools

The indoor air of schools is considered as one of the most important factors affecting the health of children. The aim of the presented research was to characterize polycyclic aromatic hydrocarbons (PAHs) in indoor and outdoor air of schools. The sampling campaign was conducted during the heating season of 2011/2012. Five primary schools from various urban settings in the city of Kaunas, Lithuania. 150 daily samples of particulate and vapor phases were collected during the sampling period. The ultrasonic extractions followed by the gas chromatography and mass spectroscopy (GS/MS) analyses were used for the determination of PAHs. The concentration of total PAHs in the PM2.5 fraction ranged from 20.3 to 131.1 ng m−3, while total suspended particles (TSP) fraction contained from 19.9 to 80.3 ng m−3 of total PAHs. The vapor phase concentration of PAHs ranged from 67.2 to 372.5 ng m−3. The most abundant PAH in both phases was naphthalene. In order to define sources of indoor and outdoor PAHs several source apportionment methods were applied. The analysis revealed that emissions from motor vehicles and fuel burning for heating purposes were the major sources of PAHs in the city of Kaunas.

Physicochemical Characterization of Particulate Emissions from a Compression Ignition Engine: The Influence of Biodiesel Feedstock

This study undertook a physicochemical characterization of particle emissions from a single compression ignition engine operated at one test mode with 3 biodiesel fuels made from 3 different feedstocks (i.e., soy, tallow, and canola) at 4 different blend percentages (20%, 40%, 60%, and 80%) to gain insights into their particle-related health effects. Particle physical properties were inferred by measuring particle number size distributions both with and without heating within a thermodenuder (TD) and also by measuring particulate matter (PM) emission factors with an aerodynamic diameter less than 10 μm (PM(10)). The chemical properties of particulates were investigated by measuring particle and vapor phase Polycyclic Aromatic Hydrocarbons (PAHs) and also Reactive Oxygen Species (ROS) concentrations. The particle number size distributions showed strong dependency on feedstock and blend percentage with some fuel types showing increased particle number emissions, while others showed particle number reductions. In addition, the median particle diameter decreased as the blend percentage was increased. Particle and vapor phase PAHs were generally reduced with biodiesel, with the results being relatively independent of the blend percentage. The ROS concentrations increased monotonically with biodiesel blend percentage but did not exhibit strong feedstock variability. Furthermore, the ROS concentrations correlated quite well with the organic volume percentage of particles - a quantity which increased with increasing blend percentage. At higher blend percentages, the particle surface area was significantly reduced, but the particles were internally mixed with a greater organic volume percentage (containing ROS) which has implications for using surface area as a regulatory metric for diesel particulate matter (DPM) emissions.

대기 중 다환방향족탄화수소 측정방법의 성능평가 - 하이볼륨 샘플링 및 GC/MS 분석방법을 대상으로

In this study, a measurement method was evaluated for the determination of polycyclic aromatic hydrocarbons (PAHs) in the ambient atmosphere. PAHs were sampled by high-volume samplers, and were then analysed with a GC/MS system. Particulate PAHs were collected on quartz fiber filter, while vapor phase PAHs were adsorbed on polyurethane foam (PUF). Target compounds included a total of 36 PAHs, which are known to be frequently detected in the urban atmosphere. It was not necessary to clean-up samples before samples were analyzed using GC/MS, and the overall performance of the method was tested by a variety of quality control and quality assurance schemes. It is generally known that the clean-up procedure can negatively affect the recovery of samples. Precision and accuracy was evaluated using SRM provided by US NIST, and the results were generally satisfactory and reliable. However, the GC/MS method appeared not to be adequate for 6-rings PAHs, such as coronene, due to its lower sensitivity. In addition, collection efficiencies for low molecular compounds, such as 2-rings PAHs, were poor because of the lower retention volume of the PUF adsorbent. As a result, it was concluded that the method based on high-volume sampling and GC/MS analysis can give very reliable data by simultaneous sampling of both particulate and vapor phases for 3-rings to 5-rings PAHs of environmental concern.

Assessment of Exposure to Polycyclic Aromatic Hydrocarbons (PAH) in Italian Asphalt Workers

The purpose of the work was the assessment of exposure to Polycyclic Aromatic Hydrocarbons (PAH), a family of ubiquitous pollutants of which some are carcinogens, in 100 Italian asphalt workers (exposed to bitumen fumes and diesel exhausts) and in a reference group of 47 ground construction operators (exposed only to diesel exhausts, reference group). The protocol included interview via questionnaires, environmental air-monitoring (active personal sampling during the work shift), dermal contamination measures (six pads placed on worker's wrist, neck, arm, chest, thigh, and ankle), and biological monitoring (determination of 1-hydroxypyrene in urine spot samples collected three at different moments: baseline after two days of vacation, before shift, and at end shift on a day in the second half of the week). Analysis of the most relevant PAH, according to the American Environmental Protection Agency, EPA, was performed by High Performance Liquid Chromatography (HPLC) by fluorimetric detector. Median airborne levels of PAH ranged from 426 to below 0.03 ng/m3. Vapor-phase PAH, apart from naphthalene, were significantly higher in asphalt workers than in the reference group. Particle-phase PAH were similar and very low (< 1 ng/m3) in both exposure groups. Exposure levels did not vary in different work-tasks. Excretion of urinary 1-hydroxypyrene (expressed by ng/g creatinine) showed a significant increase at different sampling moments in asphalt workers, smokers, and non-smokers: baseline was lower than at the beginning of the workshift, and values were even higher in the end workshift sample. Comparing the two groups, a significant difference in the levels of metabolite does not appear, whereas this trend can be viewed observing the non-smokers. All body regions monitored by pads showed equivalent values levels of Dermal Deposition Density in both exposure groups. The measured amount of dermal contamination was significantly higher in asphalt workers than in ground construction operators. In asphalt workers, skin contamination was significantly higher during asphalt paving than during asphalt mixing. Dermal Exposure Rate was calculated about threefold higher than Airborne Exposure Rate; whereas considering toxicokinetical information (Kp, lag time, experimental dermal absorption data) and hygienistic data (particle size of bitumen fume), the relevance of dermal absorption is lower than respiratory. The results of this study demonstrate that asphalt workers experience slight occupational exposure to PAH, both by inhalatory and dermal routes, resulting in a significant increase of urinary 1-hydroxypyrene during the workweek.

Influence of a large steel complex on the spatial distribution of volatile polycyclic aromatic hydrocarbons (PAHs) determined by passive air sampling using membrane-enclosed copolymer (MECOP)

Membrane-enclosed copolymer (MECOPs) samplers containing crystalline copolymers of ethylvinylbenzene-divinylbenzene in polyethylene membranes were used to assess the influence of a steel complex on the level and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) in ambient air. MECOPs were deployed at six sites in Pohang, Korea for 37 days (August 9, 2005–September 14, 2005). Fluorene, phenanthrene, anthracene, and fluoranthene were dominant PAHs with the highest contribution of phenanthrene (59%) to the total amount of vapor-phase PAHs. The spatial distribution of total PAHs in the vapor phase ranging from 76 to 1077 ng MECOP −1 and air dispersion modeling suggested that the steel complex was the major PAH source in Pohang. It was revealed that the major wind directions rather than the distance from the steel complex were a significant factor affecting the levels of PAHs at the sampling sites. Finally, we tried to convert MECOP concentrations (ng MECOP −1) to air concentrations (ng m −3) with the modified sampling rates (m 3 day −1). This study demonstrates again that passive air samplers are useful tools for spatially resolved and time-integrated monitoring of semivolatile organic compounds (SOCs) in ambient air.

Ambient Concentrations and Gas/Particle Partitioning of Polycyclic Aromatic Hydrocarbons in an Urban Site in Turkey

Atmospheric samples were collected between July 2004 and May 2005 in Bursa, Turkey, when there was no rain, and analyzed for gas and particle concentrations of polycyclic aromatic hydrocarbons (PAHs). This study targeted 15 PAH compounds. Vapor-phase PAH compositions were dominated by the more volatile PAHs, relative to the particle phase. On average, 76% of the total (gas + particulate) PAH concentration was in the vapor phase. Average total PAH concentration was 298 ± 418 ng/m3. The large seasonal concentration fluctuation was attributed to residential heating, vaporization, industrial activities, and meteorological conditions. The measured average seasonal concentrations were 55 ± 40, 187 ± 202, 645 ± 588 and 148 ± 132 ng/m3 for summer, fall, winter, and spring, respectively. The partitioning of PAHs between gas and particle phases was investigated employing the Junge-Pankow model. Plots of log gas/particle partition coefficient (K p ) versus log liquid vapor pressures (PL o) had reasonable correlations for individual samples. Experimentally determined K p values were compared with the result obtained using absorption (octanol–air partition coefficient [K OA ]) into aerosol organic matter and adsorption (K SA + K OA ) onto soot carbon models. Experimentally determined K p values were generally in the same range with the ones obtained from the models.

Emission factors from wheat and Kentucky bluegrass stubble burning: Comparison of field and simulated burn experiments

Emission factors (EFs) of PM 2.5, CO, elemental carbon (EC), particulate organic carbon (OC), polycyclic aromatic hydrocarbons (PAHs) and methoxyphenols (MPs) from post-harvest burning of wheat and Kentucky bluegrass (KBG) stubble were evaluated in a series of field burns. Integrated smoke samples were collected at ground level, upwind and downwind of the fires, and EFs were determined with the carbon balance method (validated during previous chamber experiments). These EFs were compared against EFs evaluated from previously conducted chamber burns, to determine how well the latter represent field scenarios. In general, when combustion efficiency (CE) differences were taken into account, a reasonable degree of agreement was observed between emission factors measured in the field and in the chamber, except for EC and solid+vapor phase PAHs, both from wheat burns. EC and PAHs from wheat burns were seen in higher amounts in the chamber, although the PAH data are in agreement at CEs>90%. EC overestimates might be due to a misassigned EC–OC split in the heavily loaded quartz filters from chamber burns. Poor EC and OC EF–CE correlations in KBG chamber data make the comparison with field data difficult. The particulate organic matter/OC ratios (2.1±1.3 for wheat and 1.9 for KBG) were higher than those observed during chamber experiments (1.5 for both wheat and KBG). Overestimates of EC in the chamber and possibly the condensation of oxygenated species in the field may be responsible for this difference. Though CO and CH4 EFs evaluated from ground-based samples differed from those collected on board a light aircraft, EF–CE relationships were similar. This underscores the importance of determining both the CEs and EFs simultaneously.

Compositional fractionation of polycyclic aromatic hydrocarbons (PAHs) in mosses (Hypnum plumaeformae WILS.) from the northern slope of Nanling Mountains, South China

High mountains may serve both as condenser for vapor phase persistent organic pollutants (POPs) and as barrier/sink for particulate associated less volatile POPs. The fractionation of POPs along altitudinal profiles is of interest in understanding the role of high mountains in the atmospheric transport of POPs. In the present study, polycyclic aromatic hydrocarbons (PAHs) in a selected moss species, Hypnum plumaeformae WILS, from two altitudinal profiles on the northern slope of Nanling mountains in Southern China were analyzed and compared with those in air samples. The total PAH concentration in the mosses was 310–1340 ng g−1 dry weight, with phenanthrene being the most abundant. The distribution patterns of PAHs in the moss samples matched well with those in bulk atmosphere deposition in the adjacent source areas. The PAH distribution pattern in the mosses was a composite of both particle-associated and vapor phase PAHs, with heavy PAHs are susceptible to uptake/retention by mosses than light PAHs. A plot of log (Cmoss/Cair) against log Koa gave a good linear relationship in the log Kao range of 6.7–10.2. It is suggested that the widely spread moss, H. plumaeformae WILS, can be used as an effective tool in the biomonitoring of atmospheric PAHs pollution in East Asia. The concentrations of most PAHs in the mosses generally declined with increasing altitude. In addition, there was a shift in compound pattern with an increase in the proportion of light PAHs (2–3 rings), a decrease in heavy PAHs (5–6 rings) and a relatively stable content of 4-ring PAHs. A combination of particulate scavenging and cold condensation are proposed as the major mechanisms for the compositional fractionation of PAHs along the altitudinal profile.

Polycyclic Aromatic Hydrocarbons in the Atmosphere of the Eastern Mediterranean

Atmospheric processes governing the fate of the polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of the Eastern Mediterranean were studied for a two-year period (2000-2001). Atmospheric samples were collected off-shore over the Eastern Mediterranean Sea as well as at a background station in Northeastern Crete, Greece. PAH total concentration varied from 4.1 to 57.2 ng m(-3), with >90% in the gas phase. Gas-to-particle distribution of PAHs was correlated (R2 0.75-0.98, p < 0.001) with their subcooled vapor pressure. Seasonal changes in the total concentration of PAHs were not observed, while the origin of air mass was the dominant factor determining their atmospheric concentration levels. Air masses, originating from central and eastern Europe, were associated with the highest PAH concentrations. Gas-to-particle distribution of sigmaPAHs correlated well (R2 0.75-0.98, p < 0.001) with their subcooled vapor pressure. Tropospheric ozone concentration correlated with the vapor-phase PAH concentration (p < 0.001) but less (p < 0.01) with the particulate PAH concentration. Distribution of volatile PAHs over the Eastern Mediterranean basin was uniform. Conversely, particulate PAH concentrations were higher at sampling sites located close to urban centers. Calculated relative removal rates of PAHs associated with particles were significantly higher than those of volatile members.

Emission of polycyclic aromatic hydrocarbons from diesel engine in a bus station, Londrina, Brazil

Abstract The concentrations of vapor phase polycyclic aromatic hydrocarbons (PAHs) were measured at the Central Bus Station of Londrina, where only diesel-powered vehicles circulate. The samples were collected within a period of 24 h for 14 consecutive days in January 2002. The semi-volatile PAHs were collected using a cartridge packed with XAD-2 resin, extracted under sonication and subsequently analyzed by gas chromatograph equipped with the flame ionization and mass spectrometer detectors (GC-FID and GC/MS). Ten PAH compounds were found (naphthalene, acenapthylene, acenapthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene and chrysene). The average concentrations ranged from 1.4±0.3 ng m −3 for benzo(a)anthracene to 348.0±32.7 ng m −3 for phenanthrene. The species that presented higher concentration were phenanthrene (348.0±32.7 ng m −3 ), fluorene (140.2±17.3 ng m −3 ) and naphthalene (97.7±10.3 ng m −3 ). The PAHs with two and three rings were responsible by 90.2% of the total concentration among 10 PAHs. The concentrations of PAHs were lower on Sunday in comparison with the workdays, due to the reduction of bus traffic in the station. Correlations and principal component analysis with Varimax rotation were used to estimate the local PAH emission source profile originating from the diesel exhaust. The ratio PHEN/FLU of 2.5 calculated from the results is suggested as indication from diesel combustion exhaust.

Seasonal and Spatial Variation of Polycyclic Aromatic Hydrocarbons in Vapor-Phase and PM2.5in Southern California Urban and Rural Communities

Fifteen priority polycyclic aromatic hydrocarbons (PAHs) were measured in two rural communities (Atascadero and Lompoc) located several hundred km northwest of Los Angeles and in four urban communities 40–100 km downwind of Los Angeles (San Dimas, Upland, Mira Loma, and Riverside), during all seasons, from May 2001 to July 2002. PM2.5 and vapor-phase PAHs were collected, on prebaked quartz fiber filters and PUF-XAD-4 resin, respectively, at 113 LPM, during 24 h periods, every eighth day, and quantified by HPLC-Fluorescence. At all sites vapor-phase PAHs contained > 99.9% of the total PAH mass and were dominated by naphthalene (NAP), which varied from about 60 ng m − 3 in Lompoc, a community with light traffic, to ∼580 ng m − 3 in Riverside, a community traversed by ∼200,000 vehicles day− 1. During summer pollution episodes in urban sites, NAP concentrations reached 7–30 times annual averages. Except for summer episodes, concentrations of low MW PAHs showed small seasonal variations (∼2 times higher in win...

Analysis of particle and vapour phase PAHs from the personal air samples of bus garage workers exposed to diesel exhaust.

The levels of particle and vapour phase polycyclic aromatic hydrocarbons (PAHs) derived from the diesel exhaust compounds in bus garage work were measured in winter and in summer. Five personal air samples were collected from the breathing zones of 22 garage workers every other day of consecutive weeks. Control samples (n = 22) were collected from office workers in Helsinki. Fifteen PAHs in the air samples were analysed by HPLC using a fluorescence detector. Statistically significant differences were observed between total PAH levels of the exposed workers (2241 and 1245 ng/m(3)) and the control group (254 and 275 ng/m(3)) in both winter (P < 0.001) and summer (P < 0.001). Phenanthrene, pyrene, benzo[ghi]perylene and fluoranthene were the major compounds in the particle phase, and naphthalene, phenanthrene and fluorene in the vapour phase. About 98% of PAHs measured were related to the vapour phase compounds, whereas the high molecular weight PAH compounds were detected only in the particle phase. The PAH levels in the garages were twice as high (P < 0.001) in winter as in summer. Even though the exposure levels were low in the bus garages, the low level does not allow conclusions to be drawn about the possible adverse health effects due to exposure to diesel exhaust.

Atmospheric polycyclic aromatic hydrocarbons in Seoul, Korea

Daily particulate- and vapor-phase polycyclic aromatic hydrocarbons (PAH) samples were collected at an urban site in Seoul, Korea, during five intensive sampling campaigns between October 1998 and December 1999. PAH samples collected on quartz fiber filters and PUF plugs were first extracted using dichloromethane with ultrasonication and supercritical fluid extraction methods, respectively, and then analyzed by GC/MSD/SIM. Seasonal trends in atmospheric PAH concentrations in the study area were highly influenced by fossil fuel usage for domestic heating, boundary layer height, and air temperature. The relative benzo[a]pyrene amount and particulate organic to elemental carbon ratio calculated from the measurement results suggested that photo-oxidation is not an important factor in the variation of PAH concentrations during the summer sampling periods. Correlation studies between specific PAH of the individual factors identified by principal component factor analysis and meteorological parameters revealed that both temperature and relative humidity gave greater effects on the semi-volatile PAH, PHEN and FLT, rather than on the heavier PAH, B(b+k)F and BghiP.

Atmospheric distribution of polycyclic aromatic hydrocarbons and deposition to Galveston Bay, Texas, USA

Estimates of the atmospheric deposition to Galveston Bay of polycyclic aromatic hydrocarbons (PAHs) are made using precipitation and meteorological data that were collected continuously from 2 February 1995 to 6 August 1996 at Seabrook, TX, USA. Particulate and vapor phase PAHs in ambient air and particulate and dissolved phases in rain samples were collected and analyzed. More than 95% of atmospheric PAHs were in the vapor phase and about 73% of PAHs in the rain were in the dissolved phase. Phenanthrene and napthalene were the dominant compounds in air vapor and rain dissolved phases, respectively, while 5 and 6 ring PAH were predominant in the particulate phase of both air and rain samples. Total PAH concentrations ranged from 4 to 161 ng m −3 in air samples and from 50 to 312 ng l −1 in rain samples. Temporal variability in total PAH air concentrations were observed, with lower concentrations in the spring and fall (4–34 ng m −3) compared to the summer and winter (37–161 ng m −3). PAHs in the air near Galveston Bay are derived from both combustion and petroleum vaporization. Gas exchange from the atmosphere to the surface water is estimated to be the major deposition process for PAHs (1211 μg m − 2 yr − 1), relative to wet deposition (130 μg m −2 yr − 1) and dry deposition (99 μg m −2 yr − 1). Annual deposition of PAHs directly to Galveston Bay from the atmosphere is estimated as 2 t yr −1.

Polycyclic Aromatic Hydrocarbons (PAHs) in Indoor and Outdoor Air of Hangzhou, China

Twelve polycyclic aromatic hydrocarbons were simultaneously measured in indoor and outdoor air of eight homes in Hangzhou, China in both summer and autumn in 1999. It was observed that the sum of PAHs concentrations in indoor air were ranged from 1.418 to 20.466 micrograms/m3 in summer and from 3.897 to 29.852 micrograms/m3 in autumn; the corresponding concentrations in outdoor air were between 1.380 and 20.468 micrograms/m3 in the summer and between 2.721 and 30.678 micrograms/m3 in autumn. The PAHs concentrations in indoor air generally exceeded that in the corresponding outdoor air. It was indicated that the two-, three-, and four-ring PAHs were predominantly in vapor phase, while the five-ring PAHs were primarily associated with the particulate phase. The fraction of PAHs in vapor phase will increase with the increase of temperature. Among the 12 PAHs, naphthalene was the most abundant PAHs found in indoor and outdoor air. Both in summer and autumn, it contributed more than 60% to the sum of PAHs. Because of the different functions and ventilation conditions, the concentrations of PAHs in the rooms were bedroom > kitchen > living room > balcony. By the contrast of BaP concentrations in smoker and nonsmoker's homes, we know that smoking in indoors could contribute 67% of BaP to the homes.