Ambient Air Data Research Articles

Understanding the Significance of Censored Data

Abstract The regulatory world seeks to ascertain if the levels of chemicals in the environment are at a “safe” level. Such an objective leads to dismissing results that are reported as below the detection level (BDL) as being satisfactory. Although this meets the regulatory objective, when attempting to understand the mechanisms that lead to low concentration, such data can be very important. As such, it must be treated in a statistically appropriate manner. The BDL or censored data need to be incorporated into evaluations. Moreover, there is a need to understand the data’s limits of precision. Right censored data are routinely handled for toxicological and reliability studies. BDL values produce left censored values that with a simple transfer can be flipped to right censored values by subtracting all values from a number larger than the data. Then the data can be processed using the statistical tests familiar to toxicologists. Examples of low-level stack emission data and ambient air data are examined in this article. The examples indicate that data should be clearly qualified to ensure that the reader understands the limitations. Using censored data to evaluate factors contributing to measured levels can lead to erroneous conclusions, raise concerns in the public, and lead to potentially unnecessary remedial efforts.

Ambient Air Quality Assessment in Karachi, Sindh Pakistan

Pakistan’s urban air pollution is amongst the utmost severity in the world that causes acute damage to the economy and human health. This study was designed for the assessment of ambient air quality in different areas of Karachi. The data were collected as pre-monsoon and post-monsoon season from main industrial zones of Karachi, S.I.T.E area, North Karachi industrial area, Korangi industrial area and Landhi industrial area in the year of 2017-2019. These zones are also a blend of industrial, residential, commercial and heavy traffic zones with dense populations. Ambient air data were collected for different pollutants like Nitrogen Oxides (NOx), Carbon Monoxide (CO), Sulfur Dioxide (SO2) and Particulate Matters (TSPM, PM10 and PM2.5). It is observed that in pre-monsoon, there is quite high intensity of particulate matter (TSPM, PM10 & PM2.5) present in the air, whereas CO and NO2 values found in all four zones are moderate in the air samples as prescribed by Sindh Environmental Protection Agency (SEPA) standards. It is observed specifically in Landhi, S.I.T.E Area and Korangi industrial area which are more prone to the exposure of these pollutants. In post-monsoon, the intensity of particulate matters (TSPM, PM10 & PM2.5), CO and NO2 values in all four zones are less to moderate than the values of pre-monsoon due to the seasonal effects. Study data shows that three major zones; Landhi, Korangi and S.I.T.E. industrial areas are at a high exposure to gases and other toxic elements. North Karachi is at the least risk because of having a small scale of industries present. The PM10 & PM2.5 levels average about 2 - 3-fold greater than the SEPA standards. High levels of ambient air pollutants cause severe health problems and chronic diseases on human health. Therefore the implementation of rules and regulations regarding ambient air pollutants should be more rigorous.

The concept of a virtual point of commercial accounting of natural gas energy and the algorithm for its software implementation

The issue of the quality of natural gas, including the development of tools and methods for measuring the energy of gas, is still relevant. The current «Rules for the supply of natural gas» regulate the procedure for paying consumers for natural gas, which must be carried out in cubic meters, reduced to standard conditions and expressed in energy units. According to the adopted regulatory documents, the 2021–2022 heating season should be the last one when the calculation for consumed natural gas should be made according to metric indicators. However, with the introduction of martial law in Ukraine, this period has been extended until May 1, following the date of termination or cancellation of martial law in Ukraine. At present, the natural gas metering system is not ready for the introduction of energy measurement units, especially in the domestic sector. As of today, about 10 million household gas meters with mechanical reading devices have been installed in Ukraine, most of which do not even have natural gas temperature compensation devices. Therefore, it is technically impossible to upgrade these meters to convert them to gas metering in energy units. Along with this, today there are also no domestic means of accounting for natural gas in energy units. The purpose of this work is to develop alternative approaches to the introduction of accounting for natural gas in energy units in Ukraine. The concept of a virtual point of commercial metering of natural gas energy is proposed, implemented as a software application that is part of the information and communication system, which in turn contains databases on the daily values of the natural gas combustion heat in different regions of Ukraine, the value of the ambient air temperature and data. on the heights of settlements above sea level in which gas is accounted for. An algorithm for the software implementation of a virtual point of commercial metering of natural gas energy has been developed. The estimation of metrological characteristics of determination of energy of natural gas by the offered method is carried out.

Applicability of TiO2‐Laden Asphalt Pavements in Reducing the Vehicular Pollution of Chandigarh, India

AbstractVehicular emissions play a significant role in urban‐environmental pollution. Therefore, in the present investigation, efforts are made to estimate the applicability of Titanium dioxide (TiO2)‐laden asphalt pavements in degrading the ambient Nitrogen Dioxide (NO2) in Chandigarh, India. In this regard, an artificial environment is created, and experiments are designed to degrade NO2 and Sulfur dioxide (SO2) using photocatalysis. Further, the process parameters, viz., concentration of TiO2 emulsion (25 to 125 mL m−2), Ultraviolet UV‐A irradiance (1 to 5 mW cm−2), and proportion of bitumen (4 to 6%), are optimized to achieve the maximum degradation of NO2 and SO2. Results reveal that maximum degradation of NO2 and SO2, that is, 61.91 and 55.39%, respectively, is achieved at 81.67 mL m−2 of TiO2 emulsion, 5 mW cm−2 of UV‐A irradiance, and 5.78% of bitumen. The optimized conditions of photocatalytic application are further used to treat the ambient NO2 of Chandigarh, India. Analysis of the ambient air data of Chandigarh, India, from 2005 to 2015, depicts significant contribution of vehicular emissions. It is also predicted that by 2031 the ambient concentration of NO2, may exceed the permissible limits. However, layering of asphalt payments with TiO2 could prevent such situation by 2114.

Ambient Air Quality Assessment in Karachi, Sindh Pakistan

Pakistan’s urban air pollution is amongst the utmost severity in the world that causes acute damage to the economy and human health. This study was designed for the assessment of ambient air quality in different areas of Karachi. The data were collected as pre-monsoon and post-monsoon season from main industrial zones of Karachi, S.I.T.E area, North Karachi industrial area, Korangi industrial area and Landhi industrial area in the year of 2017-2019. These zones are also a blend of industrial, residential, commercial and heavy traffic zones with dense populations. Ambient air data were collected for different pollutants like Nitrogen Oxides (NOx), Carbon Monoxide (CO), Sulfur Dioxide (SO2) and Particulate Matters (TSPM, PM10 and PM2.5). It is observed that in pre-monsoon, there is quite high intensity of particulate matter (TSPM, PM10 & PM2.5) present in the air, whereas CO and NO2 values found in all four zones are moderate in the air samples as prescribed by Sindh Environmental Protection Agency (SEPA) standards. It is observed specifically in Landhi, S.I.T.E Area and Korangi industrial area which are more prone to the exposure of these pollutants. In post-monsoon, the intensity of particulate matters (TSPM, PM10 & PM2.5), CO and NO2 values in all four zones are less to moderate than the values of pre-monsoon due to the seasonal effects. Study data shows that three major zones; Landhi, Korangi and S.I.T.E. industrial areas are at a high exposure to gases and other toxic elements. North Karachi is at the least risk because of having a small scale of industries present. The PM10 & PM2.5 levels average about 2 - 3-fold greater than the SEPA standards. High levels of ambient air pollutants cause severe health problems and chronic diseases on human health. Therefore the implementation of rules and regulations regarding ambient air pollutants should be more rigorous. .

Quantification of nitrous acid (HONO) and nitrogen dioxide (NO2) in ambient air by broadband cavity-enhanced absorption spectroscopy (IBBCEAS) between 361 and 388 nm

Abstract. This work describes an incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for quantification of HONO and NO2 mixing ratios in ambient air. The instrument is operated in the near-ultraviolet spectral region between 361 and 388 nm. The mirror reflectivity and optical cavity transmission function were determined from the optical extinction observed when sampling air and helium. To verify the accuracy of this approach, Rayleigh scattering cross sections of nitrogen and argon were measured and found to be in quantitative agreement with literature values. The mirror reflectivity exceeded 99.98 %, at its maximum near 373 nm, resulting in an absorption path length of 6 km from a 1 m long optical cavity. The instrument precision was assessed through Allan variance analyses and showed minimum deviations of ±58 and ±210 pptv (1σ) for HONO and NO2, respectively, at an optimum acquisition time of 5 min. Measurements of HONO and NO2 mixing ratios in laboratory-generated mixtures by IBBCEAS were compared to thermal dissociation cavity ring-down spectroscopy (TD-CRDS) data and agreed within combined experimental uncertainties. Sample ambient air data collected in Calgary are presented.

Performance analysis of high temperature cascade organic Rankine cycle coupled with water heating system

This paper presents performance analysis of a high temperature cascade organic Rankine cycle coupled with water heating system capable of providing maximum power output of 542 kW and hot water at 35 °C for household purposes. The analysis makes use of monthly ambient air and water temperature data of the city of Busan, South Korea as input parameters of the system. The working fluid at the exit of turbine 1 is split into two mass fractions, one providing heat to the bottom cycle (ORC II) and the other used to heat water in the water heating system. These mass fractions are adjusted according to the expected seasonal demand of hot water. Among three high critical temperature working fluids, m-xylene has been selected for the top cycle whereas R245fa has been selected for the bottom cycle among five low critical temperature working fluids. A comprehensive thermal and exergy efficiency analysis shows the performance of the system during the different months of the year. The analysis show the comparison of the winter season (when demand for hot water is high) with the summer season (when demand for hot water is low).

Research and application of ambient air quality monitoring service based on data fusion

Requirement of air quality has become higher with the living standard development and population increase. Therefore, establish the efficient ambient air data detection and fusion service system based on wireless sensor network and device cloud will be more convenient for searching existent problems that can figure them out with benefit living and leave away from the damage of air pollution. Moreover, in order to improve the accuracy and reliability of multi-source heterogeneous data in collection process according to the analysis of the limitations and the features of data collected, a proper data fusion approach based on extended Dempster-Shafer theory is proposed to expose the faulty information of sensor nodes for monitoring service. Results validate that the service can effectively improve the ability in terms of flexibility and extensibility, decrease the inherent uncertainty of the signal detection and reduce the decision-making risk.

Occurrence of Staphylococcus aureus in swine and swine workplace environments on industrial and antibiotic-free hog operations in North Carolina, USA: A One Health pilot study

Occupational exposure to swine has been associated with increased Staphylococcus aureus carriage, including antimicrobial-resistant strains, and increased risk of infections. To characterize animal and environmental routes of worker exposure, we optimized methods to identify S. aureus on operations that raise swine in confinement with antibiotics (industrial hog operation: IHO) versus on pasture without antibiotics (antibiotic-free hog operation: AFHO). We associated findings from tested swine and environmental samples with those from personal inhalable air samplers on worker surrogates at one IHO and three AFHOs in North Carolina using a new One Health approach. We determined swine S. aureus carriage status by collecting swab samples from multiple anatomical sites, and we determined environmental positivity for airborne bioaerosols with inhalable and impinger samplers and a single-stage impactor (ambient air) cross-sectionally. All samples were analyzed for S. aureus, and isolates were tested for antimicrobial susceptibility, absence of scn (livestock marker), and spa type. Seventeen of twenty (85%) swine sampled at the one IHO carried S. aureus at >1 anatomical sites compared to none of 30 (0%) swine sampled at the three AFHOs. All S. aureus isolates recovered from IHO swine and air samples were scn negative and spa type t337; almost all isolates (62/63) were multidrug resistant. S. aureus was recovered from eight of 14 (67%) ambient air and two (100%) worker surrogate personal air samples at the one IHO, whereas no S. aureus isolates were recovered from 19 ambient and six personal air samples at the three AFHOs. Personal worker surrogate inhalable sample findings were consistent with both swine and ambient air data, indicating the potential for workplace exposure. IHO swine and the one IHO environment could be a source of potential pathogen exposure to workers, as supported by the detection of multidrug-resistant S. aureus (MDRSA) with livestock-associated spa type t337 among swine, worker surrogate personal air samplers and environmental air samples at the one IHO but none of the three AFHOs sampled in this study. Concurrent sampling of swine, personal swine worker surrogate air, and ambient airborne dust demonstrated that IHO workers may be exposed through both direct (animal contact) and indirect (airborne) routes of transmission. Investigation of the effectiveness of contact and respiratory protections is warranted to prevent IHO worker exposure to multidrug-resistant livestock-associated S. aureus and other pathogens.

Assessing human metal accumulations in an urban superfund site

Butte, Montana is part of the largest superfund site in the continental United States. Open-pit mining continues in close proximity to Butte’s urban population. This study seeks to establish baseline metal concentrations in the hair and blood of individuals living in Butte, MT and possible routes of exposure. Volunteers from Butte (n=116) and Bozeman (n=86) were recruited to submit hair and blood samples and asked to complete a lifestyle survey. Elemental analysis of hair and blood samples was performed by ICP-MS. Three air monitors were stationed in Butte to collect particulate and filters were analyzed by ICP-MS. Soil samples from the yards of Butte volunteers were quantified by ICP-MS. Hair analysis revealed concentrations of Al, As, Cd, Cu, Mn, Mo, and U to be statistically elevated in Butte’s population. Blood analysis revealed that the concentration of As was also statistically elevated in the Butte population. Multiple regression analysis was performed for the elements As, Cu, and Mn for hair and blood samples. Soil samples revealed detectable levels of As, Pb, Cu, Mn, and Cd, with As and Cu levels being higher than expected in some of the samples. Air sampling revealed consistently elevated As and Mn levels in the larger particulate sampled as compared to average U.S. ambient air data.

Monitoring steel bridge renovation using lead isotopic tracing

Monitoring removal of lead (Pb) paint from steel structures usually involves analysis of environmental samples for total lead and determination of blood Pb levels of employees involved in the Pb paint removal. We used high precision Pb isotopic tracing for a bridge undergoing Pb paint removal to determine if Pb in the environmental and blood samples originated from the bridge paint. The paint system on the bridge consisted of an anti-corrosive red Pb primer top-coated with a Micaceous Iron Oxide (MIO) alkyd. Analysis of the red Pb primer gave uniform isotopic ratios indicative of Pb from the geologically-ancient Broken Hill mines in western New South Wales, Australia. Likewise waste abrasive material, as anticipated, had the same isotopic composition as the paint. The isotopic ratios for other samples lay on 2 separate linear arrays on a207Pb/204Pb versus 206Pb/204Pb diagram, one largely defined by gasoline and the majority of the ambient air data, and the other by data for one sample each of gasoline and ambient air and underwater sediments. Isotopic ratios in background ambient air samples for the project were characteristic of leaded gasoline. Air sampling during paint removal showed a contribution of paint Pb ranging from about 20 to 40%. Isotopic ratios in the blood of 8 employees prior to the commencement of work showed that 6 of these had been previously exposed to the Broken Hill Pb possibly from earlier bridge paint removal projects. One subject appeared to have increased exposure to Pb probably from the paint renovations.

Health Monitoring Considering Air Quality Index Prediction Using Neuro Fuzzy Inference Model: A Case Study of Lahore, Pakistan

For many years, improving air quality has been great attention of the whole world. It has been recognized that air pollution as a hypothetically hazardous type of environmental pollution and polluted air directly affects the human health. In Asian countries, it has converged less attention of ever growing most alarming and hazardous issue of air pollution. This paper presents a case study of Lahore city of Pakistan for the prediction of Air Quality Index (AQI) using hybrid approach of Neuro Fuzzy (NF) inference system. The ambient air data of Lahore was taken from the Environmental Protection | department (EPD) working under government of the Punjab. For results evaluation, data was recorded at different station in the period from April 2007 to May 2015. The fuzzy rules have been generated according to the Pakistan Environmental Protection Agency (PAK-EPA) standard of AQI. The NF Inference Model took the air pollutants such as Particulate Matter (PM2.5), Ozone (O3), Carbon Monoxide (CO), Sulphur Dioxide (SO2) and Nitrogen Dioxide (NO2) as inputs and predicted the air quality index as good, moderate, or unhealthy air. The results showed that NF based AQI prediction model classifies the AQI proficiently, robustly, and accurately as compared to conventional method.

Assessment of human exposure to environmental sources of nickel in Europe: Inhalation exposure

The paper describes the inhalation nickel (Ni) exposure of humans via the environment for the regional scale in the EU, together with a tiered approach for assessing additional local exposure from industrial emissions. The approach was designed, in the context of REACH, for the purpose of assessing and controlling emissions and air quality in the neighbourhood of Ni producers and downstream users. Two Derived No Effect Level (DNEL) values for chronic inhalation exposure to total Ni in PM10 (20 and 60ngNi/m3) were considered. The value of 20ngNi/m3 is the current EU air quality guidance value. The value of 60ngNi/m3 is derived here based on recently published Ni data (Oller et al., 2014). Both values are protective for respiratory toxicity and carcinogenicity but differ in the application of toxicokinetic adjustments and cancer threshold considerations. Estimates of air Ni concentrations at the European regional scale were derived from the database of the European Environment Agency. The 50th and 90th percentile regional exposures were below both DNEL values. To assess REACH compliance at the local scale, measured ambient air data are preferred but are often unavailable. A tiered approach for the use of modelled ambient air concentrations was developed, starting with the application of the default EUSES model and progressing to more sophisticated models. As an example, the tiered approach was applied to 33 EU Ni sulphate producers' and downstream users' sites. Applying the EUSES model demonstrates compliance with a DNEL of 60ngNi/m3 for the majority of sites, while the value of the refined modelling is demonstrated when a DNEL of 20ngNi/m3 is considered. The proposed approach, applicable to metals in general, can be used in the context of REACH, for refining the risk characterisation and guiding the selection of risk management measures.

Vapor Intrusion Investigation at a Site in New Jersey: A Field Study

AbstractA vapor intrusion investigation was conducted at a New Jersey site contaminated with tetrachloroethene (PCE) and trichloroethene (TCE). Several residential and commercial buildings are nearby and may be impacted, including a middle school, a learning center, and a church. Groundwater water samples were collected from the site and analyzed for volatile organic compounds (VOCs). Based on the results of the groundwater samples, subslab soil gas and indoor samples were collected from the buildings located in the area surrounding the site and analyzed for VOCs by using the U.S. Environmental Protection Agency Method TO-15. The analytical data were compared against background ambient air data and the soil gas and indoor air data were compared against New Jersey state screening levels. Both PCE and TCE were found above screening levels in groundwater and subslab soil gas samples. It is recommended that further groundwater and vapor intrusion investigations be performed at the nearby buildings and an appr...

Organic Aerosol Speciation: Intercomparison of Thermal Desorption Aerosol GC/MS (TAG) and Filter-Based Techniques

We compared measurements of organic molecular markers made using a novel Thermal Desorption Aerosol Gas Chromatograph/Mass Spectrometer (TAG) with two offline filter-based methods: solvent extraction GC/MS (SE-GC/MS) and thermal desorption GC/MS (TD-GC/MS). TAG is designed for automated, high time-resolved measurements of organic aerosol speciation. Laboratory and field measurements were performed to compare TAG and filter performance for n-alkanes, n-alkanoic acids, cholesterol, PAHs, and hopanes. Laboratory measurements of model organic aerosol mixtures of known composition were made in the Carnegie Mellon University smog chamber, and field measurements were made in downtown Pittsburgh. There was excellent agreement between techniques for hopanes and several PAHs, which are important markers for motor vehicle emissions. Agreement was also strong for moderately polar and nonpolar species in the high-concentration smog chamber experiments. Poorer agreement between filter and TAG observations was obtained for n-alkanes in ambient measurements. To further investigate the differences in n-alkane performance between these methods, potential matrix effects and internal consistency within the TAG and filter ambient air data sets were examined. We spiked a subset of ambient TAG samples with deuterated internal standards to examine potential matrix effects. Under typical conditions, there was little bias in recovery of deuterated standards. At extreme ambient aerosol levels, however, there were large biases in relative recovery, indicating matrix effects may be important under those conditions. Similar results were observed in laboratory experiments with engine lubricating oil. Applying internal standards in the TAG system would help track and correct for matrix effects influencing compound recovery.

Passive sampler‐derived air concentrations for polybrominated diphenyl ethers and polycyclic aromatic hydrocarbons in Kuwait

The present study presents, to our knowledge, the first ambient air data for a range of polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs) in Kuwait. This was achieved by concurrently deploying polyurethane foam-disk passive samplers at 14 sites over a six-week period. Calculated mean sigma5PBDE concentrations (sum of brominated diphenyl ethers [BDEs] 47, 99, 100, 153, and 154) ranged from 2.5 to 32 pg/m3 of air, with BDE 47 contributing between 39 and 65% of the sigmaPBDEs detected. Differences in relative concentrations were observed between sites, with higher concentrations measured close to suspected sources. Calculated sigmaPAH concentrations ranged from 5 to 13 ng/m3 (mean, 8.3 ng/m3). The compound distribution was dominated by three- and four-ring compounds, which constituted approximately 90% of the sigmaPAHs, with phenanthrene contributing approximately 35%. However, the proportion of five- and six-ring PAHs increased around the "oil lakes," which were formed by the torching of oil wells during the 1991 Gulf War. The oil lakes are a reservoir of PAHs that will continue feeding the atmosphere as long as they remain untreated.

Characterizing Perfluorooctanoate in Ambient Air near the Fence Line of a Manufacturing Facility: Comparing Modeled and Monitored Values

In order to improve our understanding of the nature, measurement and prediction of salts of perfluorooctanoic acid (PFOA) in air, two studies were performed along the fence line of a fluoropolymer manufacturing facility. First, a six–event, 24–hr monitoring series was performed around the fence line using the OSHA versatile sampler (OVS) system. Perfluorooctanoate concentrations were determined as perfluorooctanoic acid (PFOA) via liquid chromatography and mass spectrometry. Those data indicated that the majority of the PFOA was present as a particulate. No vapor–phase PFOA was detected above a detection limit of approximately 0.07 μg/m3. A follow–up study using a high–volume cascade impactor verified the range of concentrations observed in the OVS data. Both studies aligned with the major transport direction and range of concentrations predicted by an air dispersion model, demonstrating that model predictions agreed with monitoring results. Results from both monitoring methods and predictions from air dispersion modeling showed the primary direction of transport for PFOA was in the prevailing wind direction. The PFOA concentration measured at the site fence over the 10–week sampling period ranged from 0.12 to 0.9 μg/m3. Modeled predictions for the same time period ranged from 0.12 to 3.84 μg/m3. Less than 6% of the particles were larger than 4 μm in size, while almost 60% of the particles were below 0.3 μm. These studies are believed to be the first published ambient air data for PFOA in the environment surrounding a manufacturing facility.

A 350‐year atmospheric history for carbonyl sulfide inferred from Antarctic firn air and air trapped in ice

Carbonyl sulfide (COS) and other trace gases were measured in firn air collected near South Pole (89.98°S) and from air trapped in ice at Siple Dome, Antarctica (81.65°S). The results, when considered with ambient air data and previous ice core measurements, provide further evidence that atmospheric mixing ratios of COS over Antarctica between 1650 and 1850 A.D. were substantially lower than those observed today. Specifically, the results suggest annual mean COS mixing ratios between 300 and 400 pmol mol−1 (ppt) during 1650–1850 A.D. and increases throughout most of the twentieth century. Measurements of COS in modern air and in the upper layers of the firn at South Pole indicate ambient, annual mean mixing ratios between 480 and 490 ppt with substantial seasonal variations. Peak mixing ratios are observed during austral summer in ambient air at South Pole and Cape Grim, Tasmania (40.41°S). Provided COS is not produced or destroyed in firn, these results also suggest that atmospheric COS mixing ratios have decreased 60–90 ppt (10–16%) since the 1980s in high latitudes of the Southern Hemisphere. The history derived for atmospheric mixing ratios of COS in the Southern Hemisphere since 1850 is closely related to historical anthropogenic sulfur emissions. The fraction of anthropogenic sulfur emissions released as COS (directly or indirectly) needed to explain the secular changes in atmospheric COS over this period is 0.3–0.6%.

Passive air sampling of polycyclic aromatic hydrocarbons and polychlorinated naphthalenes across Europe.

This study presents concurrently sampled ambient air data for a range of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated naphthalenes (PCNs) at the continental scale. This was achieved with a passive air sampling system, by deploying polyurethane foam disks, which were prepared in one laboratory, sealed to prevent contamination, sent out by courier to volunteers participating in different countries, exposed for six weeks, collected, resealed, and returned to the laboratory for analysis. The study area was Europe, a region with a history of extensive persistent organic pollutants usage and emission, and with marked national differences in population density, the degree of urbanization and industrial and agricultural development. Samplers were deployed at remote, rural, and urban locations in 22 countries. Calculated air concentrations were broadly in line with those obtained by conventional active air sampling techniques, for both compound classes and for compounds existing predominantly in the gas and particle phases. The geographical compound distribution reflected suspected regional emission patterns and highlighted localized source areas. Both PAH and PCN levels varied by more than two orders of magnitude. The implications for sources are discussed.

Passive air sampling of PCBs, PBDEs, and organochlorine pesticides across Europe.

This study presents concurrently sampled ambient air data for a range of persistent organic pollutants at the continental scale. This was achieved using a passive air sampling system, deploying polyurethane foam disks, which was prepared in one laboratory, sealed to prevent contamination, sent out by courier to volunteers participating in different countries, exposed for 6 weeks, collected, resealed, and returned to the laboratory for analysis. Europe was the study area--a region with a history of extensive POPs usage and emission and with marked national differences in population density, the degree of urbanization and industrial/agricultural development. Samplers were deployed at remote/rural/urban locations in 22 countries and analyzed for PCBs, a range of organochlorine pesticides (HCB, alpha-HCH, gamma-HCH, ppDDT, ppDDE), and PBDEs. Calculated air concentrations were in line with those obtained by conventional active air sampling techniques. The geographical pattern of all compounds reflected suspected regional emission patterns and highlighted localized hotspots. PCB and PBDE levels varied by over 2 orders of magnitude; the highest values were detected in areas of high usage and were linked to urbanized areas. HCB was relatively uniformly distributed, reflecting its persistence and high degree of mixing in air. Higher gamma-HCH, ppDDT, and ppDDE levels generally occurred in South and East Europe.