This study evaluates performance of nitrogen dioxide (NO(2)) and volatile organic compound (VOC) passive samplers with corresponding reference monitors at two sites in the Detroit, Michigan area during the summer of 2005. Ogawa passive NO(2) samplers and custom-made, re-useable Perkin-Elmer (PE) tubes with Carbopack X sorbent for VOCs were deployed under week-long sampling periods for six weeks. Precise results (5% relative standard deviation, RSD) were found for NO(2) measurements from collocated Ogawa samplers. Reproducibility was also good for duplicate PE tubes for benzene, toluene, ethylbenzene, and xylene isomers (BTEX species, all </= 6% RSD). As seen in previous studies, comparison of Ogawa NO(2) samplers with reference chemiluminescence measurements suggested good agreement. Generally good agreement was also found between the PE tubes and reference methods for BTEX species.

If released in significant amounts, products formed by reactions between ozone (O(3)) and volatile organic compounds (VOCs) sorbed on activated carbon (AC) filters could degrade indoor air quality (IAQ). Heterogeneous reactions were investigated in laboratory experiments aimed at characterizing reaction products. Effluent air of AC loaded with limonene and exposed to O(3)(5.8 ppm) yielded unreacted limonene (501 +/- 197 mug/m(3)), low levels of 4-acetyl-1-methylcyclohexene (AMCH)(20 +/- 2 mug/m(3)), and limonene oxides (25 +/- 7 mug/m(3)). Most of the O(3)-limonene products remained on the AC, and most (58%) of the limonene remained unreacted on the AC after exposure to a stoichiometric excess of O(3) for 48 h. Thus, in addition to known homogenous reactions, O(3)-limonene reactions occur heterogeneously on AC but to a much lesser extent. However, the fate of 95% of the depleted limonene was not determined; much of the missing portion was attributed to desorption from the AC, but the formation of other secondary indoor air pollutants is possible. VOC-loaded AC air filters exposed to O(3) seem unlikely, however, to constitute a significant emission source of reaction products. More studies are necessary to investigate other pollutants, effects of environmental conditions, and VOC releases from AC that may be enhanced by O(3) exposure. Practical Implications Reactions between ozone and certain volatile organic compounds such as limonene (a common ingredient of many consumer products) occurring on the surface of ventilation filters could impact indoor air quality if products are released in significant amounts. This study suggests that although very small amounts of limonene adsorbed on a filter will react with O(3), ventilation filters are not likely to be significant sources of ozone oxidation products. More studies are needed to investigate whether ozone exposure enhances desorption of pollutants from ventilation filters and to measure the formation of formaldehyde and other products that are not easily retained by charcoal filters.

Concentrations of polybrominated diphenyl ethers (PBDEs) and other brominated flame retardants (BFRs) have been rapidly increasing in fish, birds, sediments, indoor environments, and humans, but emission sources and exposure pathways of these pollutants remain poorly understood. The many BFR-containing materials in buildings constitute a large reservoir of these compounds, and in-use releases from this reservoir may be a significant environmental source. To estimate in-use releases from building materials and contents in residences, we monitored 12 houses and garages in two seasons and combined measurements of BFRs in air and settled dust, air exchange rates, and other information in an approach that utilized the building as a "natural" test chamber. Results were scaled to provide a first estimate of aggregate emission rates from U.S. houses. PBDE releases total about 4 microg h(-1) per house or 20 ng m(-2) h(-1), and U.S. houses and garages collectively release about 4100 kg y(-1). Most of these releases are settled floor dust, but about 20% are released directly to the ambient environment via airborne vapor and particulate matter. These screening-level estimates are subject to considerable uncertainty, but they have an advantage in that they reflect real-world conditions based on mass balance calculations.

Emissions of particulate matter (PM) and a broad suite of target volatile organic compounds (VOCs) in total, main-stream (MS) and side-stream (SS) smoke emissions are measured for six types of commercial cigarettes. The suitability of 2,5-dimethyl furan (DMF) as a tracer for environmental tobacco smoke (ETS) is investigated using laboratory results and a field study of 47 residences. Over 30 VOCs were characterized in cigarette smoke, including several that have not been reported previously."regular tar","low tar", menthol, and nonmenthol cigarettes showed only minor differences in PM and VOC emissions. When total emissions are considered, PM emissions averaged 18 +/- 2 mg cigarette(-1) and VOC emissions averaged 3644 +/- 160 mg cigarette(-1). DMF appears to satisfy all requirements for a tracer, namely, uniqueness, detectability, similar emission factors across tobacco products (211 +/- 16 microg cigarette(-1)), consistent proportions to other ETS compounds, and behavior similar to other ETS components in relevant environments. On the basis of field study results, DMF more reliably indicated smoking status than occupant-completed questionnaires, and cigarette smoking was responsible for significant fractions of benzene (50%), styrene (49%), and other VOCs in the smoker's homes.

While few environmental measurements of brominated diphenyl ethers (BDEs) were completed prior to the mid-1990s, analysis of appropriately archived samples might enable the determination of contaminant trends back to the introduction of these chemicals. In this paper, we first investigate the stability of BDEs in archived frozen and extracted fish samples, and then characterize trends of these chemicals in rainbow smelt (Osmerus mordax) and lake trout (Salvelinus namaycush) in each of the Great Lakes between 1979 and 2005. We focus on the four most common congeners (BDE-47, 100, 99 and 153) and use a change-point analysis to detect shifts in trends. Analyses of archived fish samples yielded precise BDE concentration measurements with only small losses (0.8% per year in frozen fish tissues, 2.2% per year in refrigerated extracts). Trends in fish from all Great Lakes showed large increases in BDE concentrations that started in the early to mid-1980s with fairly consistent doubling times (generally 2-4 years except in Lake Erie smelt where levels increased very slowly), though concentrations and trends show differences by congener, fish species and lake. The most recent data show that accumulation rates are slowing, and concentrations of penta- and hexa-congeners in trout from Lakes Ontario and Michigan and smelt from Lake Ontario started to decrease in the mid-1990s. Trends in smelt and trout are evolving somewhat differently, and trout concentrations in the five lakes are now ranked as Michigan>Superior=Ontario>Huron=Erie, and smelt concentrations as Michigan>Ontario>Huron>Superior>Erie. The analysis of properly archived samples permits the reconstruction of historical trends, congener distributions, biomagnification and other information that can aid the understanding and management of these contaminants.

The adaptation of a portable gas chromatograph (GC) prototype with several unique design features to the determination of vapor-phase markers of environmental tobacco smoke (ETS) is described. This instrument employs a dual-stage adsorbent preconcentrator, two series-coupled separation columns that can be independently temperature programmed, and a detector consisting of an array of nanoparticle-coated chemiresistors, whose response patterns are used together with retention times for vapor recognition. An adsorbent pre-trap was developed to remove semi-volatile organics from the sample stream. Conditions were established to quantitatively capture two ETS markers, 2,5-dimethylfuran (2,5-DMF) and 4-ethenylpyridine (4-EP, as a surrogate for 3-EP), and to separate them from the 34 most prominent co-contaminants present in ETS using ambient air as the carrier gas. A complete analysis can be performed every 15 min. Projected detection limits are 0.58 and 0.08 ppb for 2,5-DMF and 4-EP, respectively, assuming a 1 L sample volume, which are sufficiently low to determine these markers in typical smoking-permitted environments.

Adsorbent sampling with analysis by thermal desorption, gas chromatography and mass spectrometry (TD/GC/MS) offers many advantages for volatile organic compounds (VOCs) and thus is increasingly used in many applications. For environmental samples and other complex mixtures, the MS detector typically is operated in the scan mode to aid identification of co-eluting compounds. However, scan mode does not achieve the optimal sensitivity, thus compounds occurring at low concentrations may not be detected. This paper develops and evaluates the application of a more sensitive TD/GC/MS method using selective ion monitoring (SIM) that is applicable to VOC mixtures found in ambient and indoor air. Based on toxicity and prevalence, 94 VOCs (including terpenes, aromatic, halogenated and aliphatic compounds) were selected as target compounds. Two analytical methods were developed: a conventional full scan method for ions from 29 to 270 m/z; and a SIM method using 16 time windows and different ions selected for the compounds in each window. Both methods used the same Tenax GR adsorbent sampling tubes, TD and GC parameters, and target and qualifier ions. Laboratory tests determined calibrations, method detection limits (MDLs), precisions, recoveries and storage stability. Field tests compared scan and SIM mode analyses for duplicate samples of indoor air in 51 houses and outdoor air at 41 sites. Statistical analyses included the development of error/precision models. The laboratory tests showed that most compounds demonstrated excellent precision (<10% for concentrations exceeding approximately 0.5 microg m(-3)), good linearity, near identical calibrations for scan and SIM modes, a wide dynamic range (up to 1500 microg m(-3)), and negligible storage losses after 1 month (7 compounds showed moderate losses). SIM mode MDLs ranged from 0.004 to 0.27 microg m(-3), representing a modest (1.1 to 22-fold) improvement compared to scan mode. However, in field tests the SIM method detected significantly more compounds (e.g., styrene and chloroform). Error models fit most compounds and allow quantification of errors at selected percentiles. Overall, while the new SIM method is somewhat time-consuming to develop, it offers greater sensitivity and maintains the high selectivity of traditional scan methods.

Traffic congestion increases air pollutant exposures of commuters and urban populations due to the increased time spent in traffic and the increased vehicular emissions that occur in congestion, especially "stop-and-go" traffic. Increased time in traffic also decreases time in other microenvironments, a trade-off that has not been considered in previous time activity pattern (TAP) analyses conducted for exposure assessment purposes. This research investigates changes in time allocations and exposures that result from traffic congestion. Time shifts were derived using data from the National Human Activity Pattern Survey (NHAPS), which was aggregated to nine microenvironments (six indoor locations, two outdoor locations and one transport location). After imputing missing values, handling outliers, and conducting other quality checks, these data were stratified by respondent age, employment status and period (weekday/weekend). Trade-offs or time-shift coefficients between time spent in vehicles and the eight other microenvironments were then estimated using robust regression. For children and retirees, congestion primarily reduced the time spent at home; for older children and working adults, congestion shifted the time spent at home as well as time in schools, public buildings, and other indoor environments. Changes in benzene and PM(2.5) exposure were estimated for the current average travel delay in the U.S.(9 min day(-1)) and other scenarios using the estimated time shifts coefficients, concentrations in key microenvironments derived from the literature, and a probabilistic analysis. Changes in exposures depended on the duration of the congestion and the pollutant. For example, a 30 min day(-1) travel delay was determined to account for 21+/-12% of current exposure to benzene and 14+/-8% of PM(2.5) exposure. The time allocation shifts and the dynamic approach to TAPs improve estimates of exposure impacts from congestion and other recurring events.

Effects of riboflavin photosensitizations on the stability of bisphenol A (BPA), a well-known endocrine disrupting chemical, were studied in model and real-food systems by high-performance liquid chromatography (HPLC). Concentration of BPA was significantly decreased under light exposure (P < 0.05) as the concentration of riboflavin increased while those without riboflavin under light or those with riboflavin in the dark did not change significantly (P > 0.05). Addition of 50, 100, and 200 microM sodium azide significantly increased the stability of BPA in riboflavin photosensitization with concentration dependent manner (P < 0.05), implying that a singlet oxygen or type II pathway played a role in the photodegradation of BPA. Stability of BPA in riboflavin was significantly increased in the presence of high concentration of tert-butanol, a hydroxyl radical quencher, under light storage for 80 min, indicating hydroxyl radicals were involved and contributed to the degradation of BPA, at least in part. Availability of riboflavin photosensitization on the photodegradation of BPA was tested in 2 canned tea beverages with different phenolic contents. BPA was more stable in the beverage sample with higher total phenolic contents and free radical scavenging ability. The photodegradation of BPA in riboflavin photosensitization can be an efficient way to decrease the concentration of BPA from environmental or food systems.

Brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs), have emerged as important and ubiquitous environmental pollutants, and there is a need to accurately measure airborne levels of these chemicals in both indoor and outdoor applications. We review and suggest performance criteria for BFR sampling systems, and then present the design of a new medium flow active sampler. The sampler uses a PTFE filter (47 mm, 1 microm pore size) in front of a polyurethane foam (PUF) adsorbent plug (22 mm dia, 76 mm length) with a nominal flow rate of 15 L min(-1) and a sampling period of one week, giving a sampling volume of 150 m(3). The sampler was evaluated using co-located systems to test precision, backup PUFs to test breakthrough, and distributed volume sampling to test linearity. Field experiments were conducted in five commercial buildings, one residence and outdoors at an urban site. A total of 20 BDE congeners were quantified. After appropriate cleaning of the PUF adsorbent, blank levels were negligible. Method detection limits (MDLs) were sufficiently low to quantify BDE congeners 17, 28, 71, 47, 100 and 99 in ambient air, and more than adequate to quantify these and other congeners in indoor air, where levels are typically much higher. The relative absolute deviation (RAD), based on distributed volume samples, ranged from 21%(BDE-71) to 81%(BDE-75) for indoor samples, and was somewhat higher for ambient samples. Only minimal breakthrough was detected in back-up samples, and over 80% of the samples had very low or negligible breakthrough. Humidity did not influence sampler performance. Overall, the medium-flow sampler can accurately measure PBDEs over a wide range of concentrations and applications.

We investigate a directed polymer in random media with an attractive defect at the center of the one-dimensional substrate. Without the defect, the end to end distance Deltax of the polymer follows Deltax approximately t;{1/z}, with z=3/2 and t is the polymer length. When the defect strength is weak, its contribution to Deltax is negligible. If >/=_{c}, then Deltax approaches a finite value Deltax_{sat}() in large t limit, and we find Deltax_{sat} approximately (-_{c});{-delta}, with delta approximately 3.0 . Such transition is related to the queuing phenomena of the asymmetric simple exclusion process. The polymer energy fluctuation is also discussed.

The exact pathogenesis of transient mid- and basal ventricular ballooning, a new variant of transient left ventricular (LV) ballooning, remains unknown. We report two cases of transient mid- and basal ventricular ballooning associated with catecholamines. These cases suggest that catecholamine-mediated myocardial dysfunction might be a potential mechanism of this syndrome.

Few studies were conducted on oxygenated volatile organic compounds (OVOC) because of problems encountered during the sampling/analyzing steps induced by water in sampled air. Consequently, there is a lack of knowledge of their spatial and temporal trends and their origins in ambient air. In this study, an analyzer consisted of a thermal desorber (TD) interfaced with a gas chromatograph (GC) and a flame ionization detector (FID) was developed for online measurements of 18 OVOC in ambient air including 4 alcohols, 6 aldehydes, 3 ketones, 3 ethers, 2 esters and 4 nitriles. The main difficulty was to overcome the humidity effect without loss of compounds. Water amount in the sampled air was reduced by the trap composition (two hydrophobic graphitized carbons-Carbopack B:Carbopack X), the trap temperature (held at 12.5 degrees C), by diluting (50:50) the sample with dry air before the preconcentration step and a trap purge with helium. Humidity management allowed the use of a polar CP-Lowox column in order to separate the polar compounds from the hydrocarbon/aromatic matrix. The safe sampling volume for the dual-sorbent trap 75mg Carbopack X:5mg Carbopack B was found to 405mL for ethanol by analyzing a standard mixture at a relative humidity of 80%. Detection limits ranging from 10ppt for ETBE to 90ppt for ethanol were obtained for 18 compounds for a sampling volume of 405mL. Good repeatabilities were obtained at two levels of concentration (relative standard deviation <5%). The calibration (ranging from 0.5 to 10ppb) was set up at three different levels of relative humidity to test the humidity effect on the response coefficients. Results showed that the response coefficients of all compounds were less affected by humidity except for those of ethanol and acetonitrile (decrease respectively of 30% and 20%). The target compounds analysis shows good reproducibility with response coefficient variability of less then 10% of the mean initial value of calibration for all the compounds. Hourly ambient air measurements were conducted in an urban site in order to test this method. On the basis of these measurements, ethanol, acetone and acetaldehyde have shown the highest concentration levels with an average of 2.10, 1.75 and 1.37ppb respectively. The daily evolution of some OVOC, namely ethanol and acetaldehyde, was attributed to emissions from motor vehicles while acetone has a different temporal evolution that can be probably associated with remote sources.

Volatile organic chemicals (VOC) such as aromatics and carbonyls are ubiquitous, and have environmental and health significance. This work presents a novel analytical method for simultaneously monitoring airborne carbonyls compounds and aromatic hydrocarbons. Carbonyls were collected onto an adsorbent (Tenax TA, coated with pentafluorophenyl hydrazine (PFPH)) that reacted with carbonyl groups to form thermo-stable derivatives that are suitable for subsequent analysis by thermal-desorption and GC/MS. Aromatic hydrocarbons were collected onto Tenax TA that was packed in the same sampling tube, and analyzed using the same method as carbonyls. Six carbonyls (formaldehyde, acetaldehyde, benzaldehyde, acetone, methyl ethyl ketone and methyl isobutyl ketone) and five aromatics (benzene, toluene, ethylbenzene, xylenes and styrene) were evaluated following standard test protocols. Calibration ranges were 30-200 ng per tube for most test chemicals, and 200-1000 ng per tube for formaldehyde. The analytical precision was 7% or better, and the collection efficiency, tested using a static sampling bag, was between 94 and 98%. PFPH-coated Tenax TA (for collecting carbonyls) needs to be placed in the front section of the tube, and Tenax TA in the back section (for collecting aromatics). The method detection limits of the current method ranged between 0.2 and 25 ng per tube, which corresponded to sub- to 17.2 ppbv (for formaldehyde), based on a typical 6 l sample from a sampling rate of 25 ml/min. Samples were stable for at least ten days under ambient conditions. The proposed method was also tested in the field and proved satisfactory. The proposed method is simple, feasible and has an acceptable accuracy and precision. It can thus be adopted as a reference method for making relevant measurements.

A variety of sorbents is available for the sampling of airborne organic pollutants. However, choosing the right sorbent for a certain analytical target is still a challenge. Here we present a systematic sorption study for a diverse set of up to 200 compounds at temperatures between 40 and 250 degrees C for four frequently used sorbents: Tenax TA, Chromosorb 106, Porapak N, and Carbopack F. The experimental data are used to calibrate a polyparameter linear free energy relationship (pp-LFER) for each sorbent which allows one to predict the safe sample volume and the complete sample elution volume of chemicals not tested here at any desirable temperature.

Exposure and flux-based indices of O3 risk were compared, at 19 forest locations across Bavaria in southern Germany from 2002 to 2005; leaf symptoms on mature beech trees found at these locations were also examined for O3 injury. O3 flux modelling was performed using continuously recorded O3 concentrations in combination with meteorological and soil moisture data collected from Level II forest sites. O3 measurements at nearby rural open-field sites proved appropriate as surrogates in cases where O3 data were lacking at forest sites (with altitude-dependent average differences of about 10% between O3 concentrations). Operational thresholds of biomass loss for both O3 indices were exceeded at the majority of the forest locations, suggesting similar risk under long-term average climate conditions. However, exposure-based indices estimated higher O3 risk during dry years as compared to the flux-based approach. In comparison, minor O3-like leaf injury symptoms were detected only at a few of the forest sites investigated. Relationships between flux-based risk thresholds and tree response need to be established for mature forest stands for validation of predicted growth reductions under the prevailing O3 regimes.

The applicability of a tube-type diffusive sampler as an environmental monitor for benzene, toluene, ethylbenzene and xylene (BTEX) is reported. Uptake rates have been experimentally determined for a novel type adsorbent, Tenax GR, and compared to theoretical values. It is shown, that the uptake rates are virtually independent of environmental parameters within the experimental conditions studied. The response of the sampler to transient changes in concentrations has been determined in the laboratory. It is found that the sampler is capable of following an extreme concentration profile. Field comparisons with pumped samplers have been performed and good agreement is observed between the results of the two independent methods. The samplers have also been applied as environmental monitors at different locations.

The behaviour of Tenax(R) GC, Polyurethane foam (density 0.022 g/cm(3)), Amberlite(R) XAD-2 and Amberlite(R) XAD-4 alone or in combination has been studied. Standard atmospheres containing different concentration levels of hexachlorocyclohexane and chlorobenzene isomers were generated and trapped in adsorbent cartridges. The generation of the atmosphere, the adsorption by the cartridges, the extraction of the compounds, the evaporation of the final solution and the analysis of GC/ECD have been studied. The most efficient system for trapping the test gases is the use of two cartridges connected in series, one containing Polyurethane foam and the second one containing Tenax GC. Recovery values ranging from 72% for 1,3-dichlorobenzene to 98% for gamma-hexachlorocyclohexane are obtained, most of them >90%. The SD values for all the compounds under study are around 4% for a total sampled amount of 0.5 mug of each compound.

The level of carbonyl compounds in indoor air is crucial due to possible health effects and the high prevalence of their potential sources. Therefore, selecting a convenient and rapid analytical technique for the reliable detection of carbonyl compound concentrations is important. The acetyl acetone (acac) method is a widely used standard procedure for detecting gaseous formaldehyde. For measuring formaldehyde along with other carbonyl compounds, the DNPH-method is commonly applied. The recommended procedure for measuring volatile organic compounds (VOCs) is sampling on Tenax TA, followed by thermal desorption and GC/MS analysis. In this study, different analytical techniques for the quantification of formaldehyde, pentanal, and hexanal are critically compared. It was found that the acac- and DNPH-method are in very good agreement for formaldehyde. In contrast, the DNPH-method significantly underestimates indoor air concentrations of the higher aldehydes in comparison to sampling on Tenax TA, although both methods are strongly correlated. The reported results are part of the EURIMA-WKI study on levels of indoor air pollutants resulting from construction, building materials and interior decoration.