Passive air sampling techniques are an attractive alternative to active air sampling because of the lower costs, simple deployment and retrieval methods, minimum training requirements, no need for power sources, etc.. Because of their advantages, passive samplers are now widely used not only for water and indoor, outdoor and workplace air analysis, but also for soil-gas sampling required for various purposes, including vapor intrusion studies, contamination mapping and remediation. A simple and cost effective permeation-type passive sampler, invented in our laboratory, was further developed and validated during this project. The sampler is based on a 1.8 mL crimp-cap gas chromatography autosampler vial equipped with a polydimethylsiloxane (PDMS) membrane and filled with a carbon based adsorbent. Apart from the low material costs of the sampler and ease of fabrication, the design allows for potential automation of the extraction and chromatographic analysis for high-throughput analysis. The use of highly non-polar PDMS reduces water uptake into the sampler and reduces early adsorbent saturation. The thermodynamic properties of PDMS result in moderately low sampling rate effects with temperature variations. Further, the use of PDMS allows for easy estimation of the uptake-rates based on the physicochemical properties of the analytes such as retention indices determined using capillary columns coated with PDMS stationary phase. In the thesis, the theoretical and practical aspects of the new design with regards to uptake kinetics modeling and the dependence of the calibration constants on temperature, humidity, linear flow velocity of air across the sampler surface, sampler geometry, sampling duration, and analyte concentrations are discussed. The permeability of polydimethylsiloxane toward various analytes, as well as thermodynamic parameters such as the energy of activation of permeation through PDMS membranes was determined. Finally, many applications of the passive samplers developed in actual field locations, vital for the field validation and future regulatory acceptance are presented. The areas of application of the samplers include indoor and outdoor air monitoring, horizontal and vertical soil-gas contamination profiling and vapour intrusion studies.

Passive air sampling techniques are an attractive alternative to active air sampling because of the lower costs, simple deployment and retrieval methods, minimum training requirements, no need for power sources, etc.. Because of their advantages, passive samplers are now widely used not only for water and indoor, outdoor and workplace air analysis, but also for soil-gas sampling required for various purposes, including vapor intrusion studies, contamination mapping and remediation. A simple and cost effective permeation-type passive sampler, invented in our laboratory, was further developed and validated during this project. The sampler is based on a 1.8 mL crimp-cap gas chromatography autosampler vial equipped with a polydimethylsiloxane (PDMS) membrane and filled with a carbon based adsorbent. Apart from the low material costs of the sampler and ease of fabrication, the design allows for potential automation of the extraction and chromatographic analysis for high-throughput analysis. The use of highly non-polar PDMS reduces water uptake into the sampler and reduces early adsorbent saturation. The thermodynamic properties of PDMS result in moderately low sampling rate effects with temperature variations. Further, the use of PDMS allows for easy estimation of the uptake-rates based on the physicochemical properties of the analytes such as retention indices determined using capillary columns coated with PDMS stationary phase. In the thesis, the theoretical and practical aspects of the new design with regards to uptake kinetics modeling and the dependence of the calibration constants on temperature, humidity, linear flow velocity of air across the sampler surface, sampler geometry, sampling duration, and analyte concentrations are discussed. The permeability of polydimethylsiloxane toward various analytes, as well as thermodynamic parameters such as the energy of activation of permeation through PDMS membranes was determined. Finally, many applications of the passive samplers developed in actual field locations, vital for the field validation and future regulatory acceptance are presented. The areas of application of the samplers include indoor and outdoor air monitoring, horizontal and vertical soil-gas contamination profiling and vapour intrusion studies.

In situ passive sampling is the use of a polymer sorbent to directly assess freely dissolved concentration (C [subscript free]) profiles within the environment. The primary focus herein is the use of passive sampling methods to detect and quantify persistent hydrophobic organic compounds (HOCs) in sediment porewater and surface water using solid phase microextraction (SPME) profilers with polydimethylsiloxane (PDMS) as the receiving phase sorbent. Contaminated sediment sites pose a unique challenge in terms of remediation and monitoring for several reasons including: the large number of past and ongoing sources, sediment stability, and the extent of contamination. Capping with a clean layer of material, an accepted remediation approach, can reduce risk by stabilizing the underlying sediments, isolating the water column, and reducing contaminant flux. Evaluating cap performance is challenging due to the long time frames associated with migration of HOCs. Additionally, the non-sorbing nature of most caps limits the usefulness of bulk solid measurements. An alternative is the use of concentrations in the interstitial space or porewater to examine contaminant migration in the sediments and cap. Traditionally, porewater concentrations are obtained through a conversion of bulk sediment concentrations using an assumed sediment-water partitioning coefficient. This assumption often leads to a misrepresentation of risk as not all organic carbon is created equal. An alternative is the use of passive sampling with polymer sorbents to estimate the freely available concentration, C [subscript free]. In this work the focus is on the use of solid phase microextraction with polydimethylsiloxane (SPME PDMS) as the sorbent. C [subscript free] is proportional to chemical activity; therefore an accurate measurement of C [subscript free] is necessary for risk assessment and determination of transport mechanisms and ultimately improved management of contaminated sediment sites. A non-equilibrium correction protocol using performance reference compounds (PRCs) was developed to enhance the accuracy of the SPME PDMS method to assess C [subscript free]. The protocol was validated through laboratory experiments and field trials. Deployment times can be reduced without sacrificing accuracy when using the PRC protocol. Furthermore, it was shown that mathematical models of diffusive and advective flux can be fit using parameters determined from PRC desorption. The SPME PDMS with PRCs method was used at three different remediated contaminated sediment sites, Chattanooga Creek, Eagle Harbor, and the West Branch of the Grand Calumet River, to illustrate its utility at evaluating performance of in situ remediation. Overall, the results from laboratory and field studies suggest that SPME PDMS is a valuable tool for evaluating performance of in situ sediment remediation. / text

No description available.

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are hazardous air pollutants commonly found in outdoor air. Several studies have explored the potential of vegetation to mitigate BTEX in outdoor air, but they are limited to a northern temperate climate and present conflicting results. To investigate this issue in a subtropical climate, we deployed passive air samplers for two weeks in parks and nearby residences at four locations: three in an urban area and one in a rural area in Alabama, USA. All BTEX concentrations were below health-based guidelines and were comparable to those found in several other studies in populated settings. Concentrations of TEX, but not benzene, were 3-39% lower in parks than at nearby residences, and the differences were significant. In and around two of the parks, toluene:benzene ratios fell outside the range expected for vehicular emissions (p<0.01), suggesting that there are additional, industrial sources of benzene near these two locations. The ratio of m-,p-xylene:ethylbenzene was high at all locations except one residential area, indicating that BTEX were freshly emitted. Concentrations of individual BTEX compounds were highly correlated with each other in most cases, except for locations that may be impacted by nearby industrial sources of benzene. Results of this study suggest that parks can help reduce BTEX exposure by a modest amount, but future research is needed to ascertain this potential through more measurements at higher spatial and temporal resolution and analysis of vegetation for evidence of uptake of BTEX. / Master of Science

Concentrations of PCB congeners were measured in indoor/outdoor pairs of 120 residences in two communities. More than 270 passive samplers equipped with polyurethane foam disks (PAS-PUF) were deployed and collected in the urban/industrial community of East Chicago, Indiana and rural Columbus Junction, Iowa. The sampling protocol included transport and storage of pre-cleaned and exposed PUF disks to and from the laboratory in Iowa City. The potential exposure to PCBs during transport and shipping was found to contribute no more than 10% of the PCBs measured in samples, although the sealed polyethylene bags were insufficient protection from ambient air over longer time periods. The samples were extracted and analyzed for the full suite of 209 polychlorinated biphenyls (PCBs) and are reported as a set of 158 individual or coeluting compounds. The quality control measures included laboratory and travel blanks, injection of surrogate standards in every sample, and analysis of certified PCBs in standard reference materials. Although we hypothesized that homes in East Chicago would have higher PCB concentrations than in rural Columbus Junction, this was not the case: the communities had no significant difference in either indoor or outdoor PCB concentrations (0.62 ± 0.65 ng m-3 and 1.3 ± 1.6 ng m-3 for outdoor air respectively and 1.9 ± 1.4 ng m-3 and 1.9 ± 4.4 ng m-3 for indoor air respectively). In both communities, indoor air was higher in concentration, with indoor/outdoor ratios averaging 3. The samples from the two communities do exhibit statistically different congener distributions, however, with higher molecular weight congeners more enriched in East Chicago.

Electrostatic Dust Collectors (EDCs) are a passive sampling method that has not yet been fully validated. Our first study investigated the effect of EDC mailing and EDC deployment in front of and away from heated ventilation on endotoxin concentrations. Endotoxin sampling efficiency of heated and unheated EDC cloths was evaluated. EDCs express mailed cross-country yielded no significant changes in endotoxin concentrations when dust-only samples were compared to high quality control (QC) spiked-EDCs (p=0.21) and low QC spiked-EDCs (p=0.16). EDCs were deployed in 20 apartments with one EDC placed in front of the univent heater and another EDC placed on a built-in bookshelf. Endotoxin concentrations were significantly different (p=0.049) indicating that EDC placement impacts endotoxin sampling. Heated and unheated EDCs were deployed for 7 days in farm homes. There was a significant difference between endotoxin concentrations (p=0.027). The electrostatic charge of 12 heated and 12 unheated EDC cloths were significantly different (p=0.009). These studies suggest that heating cloths may diminish their electrostatic charge and endotoxin sampling capabilities. The EDC sampling time needed to achieve detectable and reproducible loading for bioaerosols has not been systematically evaluated. In our second study, EDCs were deployed in 15 Iowa farm homes for 7-, 14-, and 28-day sampling periods to determine if endotoxin and allergens could be quantified and if loading rates were uniform (i.e. doubling from 7 to 14 days and 14 to 28 days and quadrupling from 7 to 28 days). Loadings between left and right paired EDC cloths were not significantly different and were highly correlated for endotoxin, total protein, and cat (Fel d1), dog (Can f1) and mouse (Mus m1) allergens (p<0.001). EDC endotoxin sampling had close agreement between paired samples (Pearson p=0.96, p<0.001). EDC endotoxin loading doubled from 7 to 14-day deployments but the loading rate decreased from 14 to 28 days of sampling with only a 1.38 fold increase. Allergen exposure assessment using EDCs was less satisfactory. Paired EDCs and daily Button aerosol samplers (BS) were used in our third study to concurrently sample endotoxin in 10 farm homes during 7 day periods in summer and winter. Winter sampling included an optical particle counter (OPC) for particulate size and number concentration data. OPC particulate matter (PM) data were divided into PM2.5 and PM10-2.5. Summer sampling yielded geometric mean and geometric standard deviation values of 0.82 EU/m3 (2.7) for inhalable aerosol BS and 737 EU/m2 (1.9) for EDCs. Winter values were 0.52 EU/m3 (3.1) for BS and 538 EU/m2 (3.0) for EDCs. Seven day endotoxin values of EDCs were significantly and highly correlated with the 7-day BS sampling averages (p=0.70; p<0.001). An Analysis of Variance indicated a 2.37-fold increase in EDC endotoxin concentrations for each unit increase of the ratio of PM2.5 to PM10-2.5. A 10-fold increase in BS endotoxin concentrations was associated with a 12.2-fold increase in EDC endotoxin concentrations. Our fourth study established QC protocols use of EDCs in large field studies. QCs were developed for endotoxin, peptidoglycan, and glucan for analysis alongside the Agricultural Lung Health study EDC samples. The coefficient of variation percentage (CV) for each QC was used to determine variability. For each QC, 20 EDC cloths were analyzed to establish an acceptable range (mean ± 3 standard deviations). Two QCs were established for endotoxin analysis. The high QCs were dust-spiked EDCs with a CV of 29.7%. The low QCs were spiked with E. coli standard and had a CV of 15.6%. One QC was established for peptidoglycan analysis using dust-spiked EDC extracts. Two glucan QCs were established using dust-spiked EDCs with a high CV (51.7%) and yeast-spiked EDCs with a CV of 26.0%. Endotoxin and glucan concentrations of AGLH EDC samples were found to be significantly correlated (p=0.71; p<0.0001). In conclusion, EDCs are an effective passive sampling method for endotoxin exposure assessment in farm homes.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Introduction: Nosocomial infections are infections that occur 48 hours after receiving care for an unrelated condition in a clinic or a hospital environment, many of which are resistant to at least one of the drugs most commonly used to treat them. The dental clinical settings are reservoirs for the transmission of microbes through aerosols produced by routine dental procedures.

No description available.

Le Bassin d’Arcachon souffre depuis le début des années 2000 de crises environnementales qui ont engendré la régression de l’herbier de zostères et la mortalité épisodique des naissains d’huîtres. Dès lors, la pression toxique et notamment phytosanitaire a été mise en cause et a fait l’objet de plusieurs suivis environnementaux dans la lagune et ses principaux tributaires depuis 2005. L’étude présentée ici porte sur le suivi des apports en pesticides vers le Bassin d’Arcachon par les eaux continentales. Sa plus-value réside dans l’élargissement du panel de molécules suivies, notamment avec la prise en compte des composés acides ; dans l’utilisation d’échantillonneurs passifs de type POCIS (Polar Organic Chemical Integrative Sampler) ; et dans l’acquisition d’une chronique pendant près de deux ans. Du fait de l’inadéquation du POCIS (et des autres échantillonneurs passifs aquatiques disponibles actuellement), une stratégie d’échantillonnage ponctuel mensuel a été mise en place pour le suivi des herbicides organiques acides. La mise en évidence par la suite de la prédominance de ce substances dans la contamination des tributaires du Bassin d’Arcachon a constitué une avancée majeure dans la caractérisation de la pression toxique du milieu, et a par ailleurs montré les besoins en matière d’échantillonnage passif pour ce type de contaminants. Par conséquent, des outils adaptés à leur échantillonnage ont été développés, en se basant sur des dispositifs préexistants. Le caractère intégratif de l’échantillonneur a été optimisé soit en adaptant la géométrie, soit en modifiant la nature de la phase réceptrice. Ensuite, l’aspect quantitatif des dispositifs a été amélioré en adaptant l’approche PRC (composé de performance et de référence), ou bien en utilisant un gel diffusif. / From the early 2000s, the Arcachon Bay suffers from environmental crises that have led to the decline of the Zostera spp. meadows, and to the episodic mortality of oysters spats. Therefore, the toxic pressure (including pesticides) has been questioned, and several environmental monitoring programs have been established since 2005. This new monitoring program consisted to expand the range of monitored compounds (including acidic herbicides), to use POCIS (Polar Organic Chemical Integrative Sampler) for the passive sampling of polar compounds, and to monitor continuously the main Arcachon Bay tributaries for nearly two years. Because of the inadequacy of POCIS (and other devices currently available), a monthly grab sampling strategy has been implemented for the monitoring of acidic herbicides. The highlighting of the predominance of the acidic metabolites of chloroacetanilides in the Arcachon Bay tributaries has been a major advance in the characterization of the toxic pressure, and pointed out, otherwise, the needs for a specific passive sampling tool for these contaminants. Therefore, several passive samplers have been developed, based on existing devices (POCIS and Diffusive Gradient in Thin-film). The integrative behaviour of the samplers has been first optimized by adapting the geometry (exposure surface area, and amount of receiving phase), or by changing the nature of the receiving phase. Then, the quantitative behaviour has been improved by adapting the PRC (performance and reference compound) approach, or using a diffusive gel.