Active Air Sampling Research Articles

Development of a unique multi-contaminant air sampling device for a childhood asthma cohort in an agricultural environment

This research describes the design, deployment, performance, and acceptability of a novel outdoor active air sampler to provide simultaneous measurements of multiple contaminants at timed intervals for the Aggravating Factors of Asthma in Rural Environment (AFARE) study-a longitudinal cohort of 50 children in Yakima Valley, Washington. The sampler was constructed of multiple sampling media connected to individual critical orifices and a rotary vane vacuum pump. It was connected to a timed control valve system to collect 24 hours samples every six days over 18 months. We describe a spatially representative approach with both quantitative and qualitative location criteria to deploy a network of 14 devices at participant residences in a rural region (20 × 60 km). Overall the sampler performed well, as the concurrent mean sample flow rates were within or above the ranges of recommended sampling rates for each exposure metric of interest. Acceptability was high among the study population of Hispanic farmworker participant households. The sampler design may prove useful for future urban and rural community-based studies with aims at collecting multiple contaminant data during specific time periods.

Occurrence and Seasonality of Cyclic Volatile Methyl Siloxanes in Arctic Air

Cyclic volatile methyl siloxanes (cVMS) are present in technical applications and personal care products. They are predicted to undergo long-range atmospheric transport, but measurements of cVMS in remote areas remain scarce. An active air sampling method for decamethylcyclopentasiloxane (D5) was further evaluated to include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), and dodecamethylcyclohexasiloxane (D6). Air samples were collected at the Zeppelin observatory in the remote Arctic (79° N, 12° E) with an average sampling time of 81 ± 23 h in late summer (August-October) and 25 ± 10 h in early winter (November-December) 2011. The average concentrations of D5 and D6 in late summer were 0.73 ± 0.31 and 0.23 ± 0.17 ng/m(3), respectively, and 2.94 ± 0.46 and 0.45 ± 0.18 ng/m(3) in early winter, respectively. Detection of D5 and D6 in the Arctic atmosphere confirms their long-range atmospheric transport. The D5 measurements agreed well with predictions from a Eulerian atmospheric chemistry-transport model, and seasonal variability was explained by the seasonality in the OH radical concentrations. These results extend our understanding of the atmospheric fate of D5 to high latitudes, but question the levels of D3 and D4 that have previously been measured at Zeppelin with passive air samplers.

Microbial isolations from maxillofacial operation theatre and its correlation to fumigation in a teaching hospital in India.

Postoperative infection and sepsis remain a major cause of morbidity among patients undergoing surgery. Maintenance of strict asepsis is essential if post-operative infection and its consequences are to be minimized. In developing countries maintenance of asepsis in most operation theatres is limited to fumigation and mopping. Clinical trials have confirmed that 80-90% of bacterial contaminants found in wound after surgery come from microbes present in air of operating theatre. A study was conducted to evaluate the microbiological contamination of maxillofacial operation theatres in India and its correlation to weekly fumigation. A total of 6,723 culture plates, including 2,241 air and 4,482 swab samples were studied. Samples were collected at prefumigation, midcycle and post-fumigation stages and were cultured over three different medias. Predominant bacteria identified were Staphylococcus aureus (76 out of 83 samples by active air sampling) followed by Streptococcus while Aspergillus was the main fungal isolate. Formaldehyde based fumigation decreased the colony forming units (cfu/m(3)) of all organisms in different samples and was found to be highly effective against Fungi and E. coli. Literature suggests that for conventional operating theatres the bioload should not exceed 35cfu/m(3) in an empty theatre. In our study the cfu levels were always lower immediately after fumigation was carried out; however they moved up beyond this limit as the days passed. This implies that once a week fumigation with formaldehyde is less than optimal to achieve acceptable levels of disinfection.

Improving the spatial resolution of atmospheric polycyclic aromatic hydrocarbons using passive air samplers in a multi-industrial city

The source–receptor relationship of polycyclic aromatic hydrocarbons (PAHs) in the industrial city has been generally investigated using active air samplers (AAS), but they only provide low spatial resolution data. In this study, the spatial resolution of PAHs was improved by the use of polyurethane foam based passive air samplers (PUF-PAS). We deployed 40 passive air samplers in duplicate at 20 sites in the largest industrial city of Ulsan, South Korea during winter (January 7–February 25, 2011). Among the 16 US-EPA priority PAHs, 13 compounds excluding naphthalene, acenaphthylene, and acenaphthene were selected for the calculation of air concentrations. The level of gaseous ∑13PAHs in Ulsan (mean: 43ng/m3) was not as high as we expected due to prevailing winds which transported large amounts of PAHs to the East Sea. The spatial distribution of PAHs, principal component analysis, and diagnostic ratios suggested the influence of PAH emissions from industrial complexes to the surrounding areas. This study demonstrated that the source–receptor relationship of PAHs in the industrial area can be more clearly understood using passive air samplers.

소나무잎을 Passive Air Sampler(PAS)로 이용하여 대기 중 PCBs 농도 추정

Objective: This study was carried out to use pine needles as a passive air sampler (PAS) of atmospheric Polychlorinated Biphenyls (PCBs). Methods: PCB concentrations in ambient air (<TEX>$C_a$</TEX>, ng/<TEX>$m^3$</TEX>) and deposited on pine needles (<TEX>$C_p$</TEX>, ng/g dry) were analyzed simultaneously from June 1 to December 31. Air samples were taken using a low volume PUF active air sampler and the overall average air volume was about 900-1,000 <TEX>$m^3$</TEX>. Pine needles were collected at the end of August and December near the air sampler. Results: <TEX>$C_a$</TEX> were higher at higher air temperature and lower chlorinated PCB congeners, but <TEX>$C_p$</TEX> showed irregular distribution. The average PCB sampling rates from air to pine needles were 0.116 (0.002-0.389) <TEX>$m^3$</TEX>/day - g dry. Conclusions: A poor correlation was shown between <TEX>$C_a$</TEX> and <TEX>$C_p$</TEX>. However, a good correlation was shown between the logarithm of octanol-air partitioning coefficient (<TEX>$logK_{oa}$</TEX>) and log (<TEX>$C_p/C_a$</TEX>), and the interrelation was better with longer sampling time (June to December) than shorter sampling time (June to August). The average PCB sampling rates from air to pine needles were the lowest with respect to PUF disk, XAD-2 resin and semipermeable membrane devices (SPMDs) PAS. The average ratio (<TEX>$C_{a-calc}/C_{a-meas}$</TEX>) of calculated (<TEX>$C_{a-calc}$</TEX>) and measured (<TEX>$C_{a-meas}$</TEX>) PCB concentration was 0.69 with a shorter sampling time and 1.24 with a longer, so <TEX>$C_{a-calc}$</TEX> was close to <TEX>$C_{a-meas}$</TEX>. It was found that pine needles can be used as PAS of atmospheric PCBs, and are especially suitable for long-time PAS.

Dispersal patterns of polybrominated diphenyl ethers (PBDEs) in the vicinity of an automotive shredding and metal recycling facility

Concentrations of polybrominated diphenyl ethers (PBDEs) were determined in air samples from near a large outdoor automotive shredding and metal recycling facility and the surrounding local area. This was done using a combination of active air samplers (AAS) measuring particle–associated and vapor–phase compounds, and, for the first time, passive air samplers (PAS) consisting of polyurethane foam (PUF) deployed at high spatial resolution around the facility. AAS data showed average levels of Σ11PBDE in the adjacent commercial precinct (439±222pg m−3) were on average a factor of 50 times higher than those in the residential area 1.5km away (8.5±3.6pg m−3). In addition, the PBDE composition in air was different between the commercial and residential areas with quantifiable concentrations for eleven PBDEs (BDE-28, -47, -100, -99, -153, -183, -197, -196, - 206, -207 and -209) in the commercial area. In contrast, only five of these congeners were detected in the residential area. Congener BDE-209 dominated the profile in air at both active air monitoring sites (i.e. commercial and residential) and was entirely associated with the particulate–phase, contributing on average 63% of the Σ11PBDE mass in samples. Congener composition in PAS deployed across the field study area (16km2) were also dominated by BDE-209 with this congener representing 75% of the Σ11PBDE mass in samples, a proportion similar to that observed in active samples. The attenuation of Σ11PBDEs in PAS vs. distance from the recycling facility was best fitted using an empirical exponential decay model (r2=0.89). Model results indicated the major wind direction plays only a minor role in determining the observed spatial distribution of PBDEs.

Assessment of airborne exposures and health in flooded homes undergoing renovation.

In June 2008, the Cedar River crested flooding more than 5000 Cedar Rapids homes. Residents whose homes were flooded were invited to participate in this study. Household assessments and resident interviews were conducted between November 2008 and April 2009. We characterized exposures and symptoms experienced by individuals inhabiting 73 flood-damaged homes. Active air sampling and passive electrostatic dust collectors were used to assess exposures to culturable mold, culturable bacteria, fungal spores, inhalable particulate matter (iPM), endotoxin, glucans, allergens, lead, asbestos, radon, carbon dioxide, and carbon monoxide. Wall moisture levels and relative humidity were also measured. Exposures and questionnaire-based health assessments were compared at two levels of remediation, in-progress and completed. Homes with remediation in-progress (N = 24), as compared to the completed homes (N = 49), had significantly higher airborne concentrations of mold, bacteria, iPM, endotoxin, and glucan. Residents of in-progress homes had a significantly higher prevalence of doctor-diagnosed allergies (adjusted OR = 3.08; 95% CI: 1.05, 9.02) and all residents had elevated prevalence of self-reported wheeze (adjusted OR = 3.77; 95% CI: 2.06, 6.92) and prescription medication use for breathing problems (adjusted OR = 1.38; 95% CI: 1.01, 1.88) after the flood as compared to before. Proper post-flood remediation led to improved air quality and lower exposures among residents living in flooded homes. The number and severity of floods is on the rise, and health departments need evidence-based information to advise homeowners on recovery after such disasters. Our study suggests that proper remediation of flood-damaged homes can reduce bioaerosols to acceptable levels but exposures are significantly increased while remediation is in-progress leading to an increased burden of allergy and allergic rhinitis.

PCBs, PBDEs, and PAHs in Toronto air: Spatial and seasonal trends and implications for contaminant transport

The distributions of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of Toronto, Canada and the surrounding suburban/rural area were examined. A series of temporally- and spatially-distributed air samples was collected over a 1-year period with a high-volume active air sampler at one downtown site and polyurethane foam passive air samplers at 19 sites. Passive sampler air concentrations of ΣPAHs ranged from 0.27 to 51ng/m3. Concentrations of ΣPCBs ranged from 6.0 to 1300pg/m3, and concentrations of ΣPBDEs ranged from 0.47 to 110pg/m3. All compounds exhibited the highest concentrations in the urban core, and lowest concentrations in the surrounding rural areas, however the exact ratio depended on location since concentrations varied considerably within the city. Results from the application of a radial dilution model highlighted the influence of the central business district (CBD) of the city as a source of contaminants to the surrounding environment, however the radial dilution comparison also demonstrated that sources outside the CBD have a significant influence on regional contaminant concentrations.A strong relationship between temperature and partial pressure of the gas-phase PCBs, low molecular weight PBDEs and less-reactive PAHs suggested that their dominant emissions originated from temperature-controlled processes such as volatilization from local sources of PCBs, PAHs and PBDEs at warm temperatures, condensation and deposition of emissions at cold temperatures, and ventilation of indoor air with elevated concentrations. The relationship between temperature and atmospheric PAH concentrations varied along the urban–rural gradient, which suggested that in highly urbanized areas, such as downtown Toronto, temperature-related processes have a significant impact on air concentrations, whereas winter emissions from domestic heating have a greater influence in areas with less impervious surface coverage.

Improved correction method for using passive air samplers to assess the distribution of PCNs in the Dongjiang River basin of the Pearl River Delta, South China

Abstract An improved correction method was established using passive air samplers to assess the distributions of polychlorinated naphthalenes (PCNs) in the eastern Pearl River Delta, South China. This method was based on a joint correction that used the active air sampling rate and the addition of depuration compounds. As a correction factor, the depuration compounds’ properties do not need to be similar to the target compounds. The total PCN air concentrations ranged from 6.4 to 832, with an average of 148 ± 201 pg m −3 in the study area, while the TEQ of the PCNs ranged from 1.2 × 10 −4 to 2.6 × 10 −2 pg m −3 . High concentrations of PCNs were mostly observed in the highly industrialized areas. The PCN air levels were remarkably increased in winter compared with summer. Tri-CNs was the most dominant homologue group, while CN 24 was the most dominant congener. The high proportion of combustion-related PCNs suggests that the contribution of combustion sources to the PCN air burden has been significant recently in comparison with historical emissions.

Traffic flow in the operating room: An explorative and descriptive study on air quality during orthopedic trauma implant surgery

Understanding the protective potential of operating room (OR) ventilation under different conditions is crucial to optimizing the surgical environment. This study investigated the air quality, expressed as colony-forming units (CFU)/m(3), during orthopedic trauma surgery in a displacement-ventilated OR; explored how traffic flow and the number of persons present in the OR affects the air contamination rate in the vicinity of surgical wounds; and identified reasons for door openings in the OR. Data collection, consisting of active air sampling and observations, was performed during 30 orthopedic procedures. In 52 of the 91 air samples collected (57%), the CFU/m(3) values exceeded the recommended level of <10 CFU/m(3). In addition, the data showed a strongly positive correlation between the total CFU/m(3) per operation and total traffic flow per operation (r = 0.74; P = .001; n = 24), after controlling for duration of surgery. A weaker, yet still positive correlation between CFU/m(3) and the number of persons present in the OR (r = 0.22; P = .04; n = 82) was also found. Traffic flow, number of persons present, and duration of surgery explained 68% of the variance in total CFU/m(3) (P = .001). Traffic flow has a strong negative impact on the OR environment. The results of this study support interventions aimed at preventing surgical site infections by reducing traffic flow in the OR.

Passive Sampling of Gaseous Persistent Organic Pollutants in The Atmosphere

The polyurethane foam (PUF) disk-based passive air samplers (PAS), mounted inside two aluminium bowls to buffer the air flow to the disk and to shield it from precipitation and sunlight, were used for the collection of atmospheric POPs in Singapore during April 2008eJune 2008. Data obtained from PAS measurements are compared to those from active high-volume air sampling (AAS). Single factor ANOVA tests show that there were no significant differences in chemical distribution profiles between actively and passively collected samples(PAHs, F=3.38×10-8) < Fcritica l= 4.17 with p>0.05; OCPs, F=2.71×10-8< Fcritical = 4.75 with p > 0.05). The average air-side mass transfer coefficient (kA) for PAS, determined from the loss of depuration compounds such as 13C6-HCB (1000 ng), 13C12 - 4,4’ DDT (1000 ng) and 13C12-PCB 101 (1000 ng)spiked on the disks prior to deployment, was 0.12 ± 0.04 m s-1. These values are comparable to those reported previously in the literature. The average sampling rate was 3.78 ± 1.83 m3 d- 1 for the 365cm2 PUF disk. Throughout the entire sampling period (∼68 d), most of the PAHs and all OCPs exhibited a linear uptake trend on PAS, while naphthalene, acenaphthylene, acenaphthene and fluorene reached the curvilinear phase after the first ∼30 d exposure. Theoretically estimated times to equilibrium (teq) ranged from around one month for Acy to hundreds of years for DB(ah)A. Sampling rates, based on the time integrated active sampling-derived concentrations and masses collected by PUF disks during the linear uptake phase, were determined for all target compounds with the average values of 2.50 m3 d-1 and 3.43m3 d-1 for PAHs and OCPs, respectively. More variations were observed as compared to those from th depuration study. These variations were most likely due to the difference of physicochemical properties of individual species. The validation and calibration work conducted for PAS in this study clearly indicates that it would be feasible to use such an economic PAS for routine measurements of POPs in the tropical atmosphere at a large network of sampling locations.

Spatial mapping of city-wide PBDE levels using an exponential decay model

Passive air samplers (PAS) consisting of polyurethane foam (PUF) disks were deployed at 6 outdoor air monitoring stations in different land use categories (commercial, industrial, residential and semi-rural) to assess the spatial distribution of polybrominated diphenyl ethers (PBDEs) in the Brisbane airshed. Air monitoring sites covered an area of ~1143 km(2) and PAS were allowed to accumulate PBDEs in the city's airshed over three consecutive seasons commencing in the winter of 2008. The average sum of five (∑(5)) PBDEs (BDEs 28, 47, 99, 100 and 209) levels were highest at the commercial and industrial sites (12.7 ± 5.2 ng PUF(-1)), which were relatively close to the city center and were a factor of 8 times higher than residential and semi-rural sites located in outer Brisbane. To estimate the magnitude of the urban 'plume' an empirical exponential decay model was used to fit PAS data vs. distance from the CBD, with the best correlation observed when the particulate bound BDE-209 was not included (∑(5)-209) (r(2) = 0.99), rather than ∑(5) (r(2) = 0.84). At 95% confidence intervals the model predicts that regardless of site characterization, ∑(5)-209 concentrations in a PAS sample taken between 4-10 km from the city centre would be half that from a sample taken from the city centre and reach a baseline or plateau (0.6 to 1.3 ng PUF(-1)), approximately 30 km from the CBD. The observed exponential decay in ∑(5)-209 levels over distance corresponded with Brisbane's decreasing population density (persons/km(2)) from the city center. The residual error associated with the model increased significantly when including BDE-209 levels, primarily due to the highest level (11.4 ± 1.8 ng PUF(-1)) being consistently detected at the industrial site, indicating a potential primary source at this site. Active air samples collected alongside the PAS at the industrial air monitoring site (B) indicated BDE-209 dominated congener composition and was entirely associated with the particulate phase. This study demonstrates that PAS are effective tools for monitoring citywide regional differences however, interpretation of spatial trends for POPs which are predominantly associated with the particulate phase such as BDE-209, may be restricted to identifying 'hotspots' rather than broad spatial trends.

Polyfluorinated Compounds in Serum Linked to Indoor Air in Office Environments

We aimed to investigate the role of indoor office air on exposure to polyfluorinated compounds (PFCs) among office workers. Week-long, active air sampling was conducted during the winter of 2009 in 31 offices in Boston, MA. Air samples were analyzed for fluorotelomer alcohols (FTOHs), sulfonamides (FOSAs), and sulfonamidoethanols (FOSEs). Serum was collected from each participant (n = 31) and analyzed for 12 PFCs including PFOA and PFOS. In air, FTOHs were present in the highest concentrations, particularly 8:2-FTOH (GM = 9920 pg/m(3)). FTOHs varied significantly by building with the highest levels observed in a newly constructed building. PFOA in serum was significantly correlated with air levels of 6:2-FTOH (r = 0.43), 8:2-FTOH (r = 0.60), and 10:2-FTOH (r = 0.62). Collectively, FTOHs in air significantly predicted PFOA in serum (p < 0.001) and explained approximately 36% of the variation in serum PFOA concentrations. PFOS in serum was not associated with air levels of FOSAs/FOSEs. In conclusion, FTOH concentrations in office air significantly predict serum PFOA concentrations in office workers. Variation in PFC air concentrations by building is likely due to differences in the number, type, and age of potential sources such as carpeting, furniture, and/or paint.

Pollution Level and Distribution of PCDD/PCDF Congeners between Gas Phase and Particulate Phase in early Spring Air of Dalian, China

Ambient air of Dalian was sampled with active high-volume air samplers in early spring time. The concentrations and the congeners between gas phase and particulate phase of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) in the air were measured. Samples analysis results showed that the concentration of PCDD/Fs in particulate phase was higher than that in gas phase. The ratio of PCDD to PCDF in gaseous phase and particulate phase was lower than 0.4. The main sources of atmospheric PCDD/Fs in Dalian early spring season were coal-related source. The total I-TEQ in gaseous phase and particulate phase was 30.3 and 143.6 fg m-3, respectively. The I-TEQ of Dalian early spring atmosphere was lower than international standard, the atmospheric quality in Dalian was better.

Air exposure assessment of TDI and biological monitoring of TDA in urine in workers in polyurethane foam industry

ObjectivesToluene diisocyanate (TDI) is used in the manufacturing process of polyurethane (PU) foams and is a potent inducer of occupational asthma. The objective of this study was to evaluate the...

Pollution level and distribution of PCDD/PCDF congeners between vapor phase and particulate phase in winter air of Dalian, China

In December 2009, ambient air was sampled with active high-volume air samplers at two sites: on the roof of the No. l building of Dalian Jiaotong University and on the roof of the building of Dalian Meteorological Observatory. The concentrations and the congeners between vapor phase and particulate phase of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) in the air were measured. Sample analysis results showed that the concentrations of PCDD/Fs in particulate phase was higher than that in gaseous phase. The ratio of PCDD to PCDF in gaseous phase and particulate phase was lower than 0.4 in all samples. The total I-TEQ value in gaseous phase and particulate phase was 5.5 and 453.8 fg/m 3 at Dalian Jiaotong University, 16.6 and 462.1 fg/m 3 at Dalian Meteorological Observatory, respectively. The I-TEQ value of Dalian atmosphere was 5.5-462.1 fg/m 3 which was lower than international standard, the atmospheric quality in Dalian is better.

Relationship of air sampling rates of semipermeable membrane devices with the properties of organochlorine pesticides

The organochlorine pesticides (OCP) in Eastern-Barvaria at Haidel 1160 m a.s.l. were monitored with a low volume active air sampler and semi-permeable membrane devices (SPMD). The air sampling rates (R air) of SPMD for OCP were calculated. Quantitative structure-property relationship (QSPR) models of R air of SPMD were developed for OCP with partial least square (PLS) regression. Quantum chemical descriptors computed by semi-empirical PM6 method were used as predictor variables. The cumulative variance of the dependent variable explained by the PLS components and determined by cross-validation (Q 2 cum), for the optimal models, is 0.637, indicating that the model has good predictive ability and robustness, and could be used to estimate R air values of OCP. The main factors governing R air of OCP are intermolecular interactions and the energy required for cave-forming in dissolution of OCP into triolein of SPMD.

QSPR study about sampling rates of semipermeable membrane devices for monitoring of organochlorine pesticides in Alps air

Organochlorine pesticides (OCP) were monitored at the Weissfluhjoch site (Switzerland) and the top of Mt. Sonnblick (Austria) with a low volume active air sampler and semipermeable membrane devices (SPMD). The air sampling rates (Rair) of the SPMD for OCP were calculated. Statistical tests showed that there was no significant difference between Rair at the two different sampling sites. Quantitative structure-property relationship (QSPR) models of the Rair of the SPMD were developed for OCP using partial least square (PLS) regression. Quantum chemical descriptors computed by the semi-empirical PM6 method were used as predictor variables. The cumulative variance of the dependent variable explained by the PLS components and determined by cross-validation (Q2cum) was >0.818 for each optimal model. This indicates that the model has good predictive ability and robustness. The Rair of the SPMD for OCP is related to the total energy, the van der Waals area and the total dipole moment of the OCP molecules. The main factors governing Rair values of OCP are intermolecular interactions and the energy required for cavity-formation in dissolution of OCP into triolein of the SPMD. The linear correlation coefficient between predicted and experimental values were all >0.921.

Spatial variability of POPs in European background air

Abstract. Passive air samplers (PAS) were deployed at 86 European background sites during summer 2006 in order (i) to gain further insight into spatial patterns of persistent organic pollutants (POPs) in European background air and, (ii) to evaluate PAS as an alternative sampling technique under EMEP (Co-operative programme for monitoring and evaluation of the long-range transmissions of air pollutants in Europe). The samples were analyzed for selected PCBs, HCHs, DDTs, HCB, PAHs and chlordanes, and air concentrations were calculated on the basis of losses of performance reference compounds. Air concentrations of PCBs were generally lowest in more remote areas of northern Europe with elevated levels in more densely populated areas. γ-HCH was found at elevated levels in more central parts of Europe, whereas α-HCH, β-HCH and DDTs showed higher concentrations in the south-eastern part. There was no clear spatial pattern in the concentrations for PAHs, indicative of influence by local sources, rather than long range atmospheric transport (LRAT). HCB was evenly distributed across Europe, while the concentrations of chlordanes were typically low or non-detectable. A comparison of results obtained on the basis of PAS and active air sampling (AAS) illustrated that coordinated PAS campaigns have the potential serve as useful inter-comparison exercises within and across existing monitoring networks. The results also highlighted limitations of the current EMEP measurement network with respect to spatial coverage. We finally adopted an existing Lagrangian transport model (FLEXPART) as recently modified to incorporate key processes relevant for POPs to evaluate potential source regions affecting observed concentrations at selected sites. Using PCB-28 as an example, the model predicted concentrations which agreed within a factor of 3 with PAS measurements for all except 1 out of the 17 sites selected for this analysis.

Evaluation of passive air sampler calibrations: Selection of sampling rates and implications for the measurement of persistent organic pollutants in air

Polyurethane foam (PUF) passive air samplers (PAS) are a common and highly useful method of sampling persistent organic pollutants (POP) concentrations in air. PAS calibration is necessary to obtain reasonable and comparable semi-quantitative measures of air concentrations. Various methods are found in the literature concerning PAS calibration. 35 studies on PAS use and calibration are examined here, in conjunction with a study involving 10 PAS deployed concurrently in outdoor air with a low-volume air sampler in order to measure the sampling rates of PUF-PAS for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic musks (PCMs), and polycyclic aromatic hydrocarbons (PAHs). Based on this analysis it is recommended that (1) PAS should be assumed to represent bulk rather than gas-phase compound concentrations due to the sampling of particle-bound compounds, (2) calibration of PAS sampling rates is more accurately achieved using an active low-volume air sampler rather than depuration compounds since the former measures gas- and particle-phase compounds and does so continuously over the deployment period of the PAS, and (3) homolog-specific sampling rates based on KOA groupings be used in preference to compound/congener-specific or single sampling rates.