Heat stress is one of many physical agents to which thousands of workers are under constant exposure. Oftentimes it is necessary to work above the WBGT-based heat stress exposure limits. It is therefore important to consider alternative measures that include an exposure time limit to manage the heat stress. Predicted Heat Strain (PHS) (ISO7933) is one of those alternatives. PHS uses both personal factors like height and weight and job factors of environment, metabolic rate and clothing. The purpose of this project is to determine whether the PHS is an adequate method to predict short term exposure limits. The project’s data were taken from a prior experimental study where twelve participants were exposed to five different heat stress levels while over three different clothing ensembles. A total of 15 combinations of clothing and environment were tried. The PHS process was adapted to an Excel function using Visual Basic for Applications (VBA) (called fPHSTre). fPHSTre predicted a rectal temperature (Tre) at the exposure limit using both personal and job factors and then using standard values for personal factors. Based on analysis of variance, the fPHSTre adequately accounted for clothing, specifically evaporative resistance, using either fixed or individual data for predicted Tre on the experimental trials. In general, the PHS model could be used to reliably assess time limiting safe exposures in occupational settings for workers in hot environments.

The purpose of this study was to investigate whether or not differing base metals and filler wires used during welding processes contributed to differing amounts of ultrafine particles (UFP) and nanoparticles being emitted during the welding procedure. The study was also conducted to determine UFP and nanoparticle exposure in the breathing zones of the welders as well as the breathing zones of pipefitters and fire watchers, who commonly sit 6ft behind the welding arc. In order to determine if UFP and NP exposures differed with base metal and filler wire, all welding processes utilized the same welding machine for metal inert gas (MIG), the same wire speed, and the same voltages during each welding process. The only variation in welding procedures were cover gases used, base metals, and filler wires. Measurements gathered during welding procedures were conducted in the breathing zone of the welder and pipefitters consisted of UFP measurements taken by two different condensation particle counters (CPC), which operated in synchrony at the start and cessation of the welding process. NP measurements were taken by a NanoScan Scanning Mobility Particle Sizer (SMPS) and were also placed in the breathing zone of the welder. Lastly, particle characterization measurements for transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were gathered using a filter attached to a high flow pump, which was placed in the breathing zone of the welder. According to the results, base metal and filler wire do emit differing amounts of NP and UFP during the welding processes. Carbon steel emits the highest amount of nanoparticles, while stainless steel emits the second highest amount, and inconel emits the least. The results also concluded that welders are exposed to a greater concentration of nanoparticles and UFPs than those experienced by pipefitters who stand 6ft from the welding arc.

Chlorpyrifos (CPF) is a popular organophosphorus insecticide that is heavily used in the agriculture industry as a means of pest control. Chlorpyrifos is known for its toxic effect to inhibit the enzyme acetylcholinesterase (ACHE) in humans and is widely used in areas of California where the site of application is close to occupied areas, such that exposures to residents and bystanders can occur due to secondary drift. Secondary drift refers to the volatilization of a pesticide from the surface to which it was applied (e.g. soil or plant foliage) and subsequent off-site movement in ambient air. Secondary drift is different from spray drift, which occurs during and very shortly after application. The goal of this thesis is to evaluate existing measurements of secondary drift from ambient air measurements of CPF available from California’s Air Monitoring Network (AMN), in comparison to predictions using a state-of-the-art dispersion model. Pesticide use data were obtained from the California Department of Pesticide Regulation (CDPR) website and was compiled to form scenarios to be modeled and compared against measurements taken throughout the year. Probability distributions for the measured and predicted CPF concentrations resulted in correlations ranging from 3% to 91% depending on the year and modeled scenario. Overall the model overpredicted air concentrations for the modeled scenarios, providing conservative values for risk assessment purposes.

Sampling of airborne dust in industry is influenced by the potential health effects associated with human exposure. Health effects depend on mass concentration and particle size which influences the site of pulmonary deposition. Occupational diseases tend to be associated with dust deposition in specific regions of the respiratory tract. The ACGIH size selective TLVs are expressed in three forms: Inhalable Particulate Matter, Thoracic Particulate Matter, and Respirable Particulate Matter. In pneuomoconioses, the amount of dust deposited in the lungs can be estimated by sampling the respirable fraction. Dose-response relationships are derived by relating the health experience of workers to the extent of their exposure to respirable dust. It can be readily seen that validity of these relationships depends primarily on the accuracy of estimation of the exposure dose. Different sampling techniques, such as impactors, horizontal elutriators and cyclones were used for decades to estimate the exposure to respirable dusts. Cyclones have been the most widely utilized. However, the performance curve of the cyclone is considerably different from observed dust deposition data in the human alveolar compartment. Current methods of measuring respirable dust overestimate that dust fraction, which results in underestimating the agent’s toxicity in dose-response relationships. In this investigation, a new concept for sampling respirable dust was proposed and validated. The goal of this study was to design a combined impactor/cyclone device that provides better estimation of the amount of respirable dust. The objectives of this study were: 1) to calibrate ten single-stage impactors previously deigned and machined by Dr. Hammad, 2) to obtain the collection efficiency curves of ten impactor-cyclone combinations by superimposing the collection efficiency curves of impactors on the well-defined cyclone efficiency curve, and 3) to compare the combined efficiency curves to actual human alveolar deposition data, and thus validate this new concept for sampling of respirable dust. The experiment was conducted in a 20’’x20’’x20’’ aerosol testing chamber constructed from aluminum with a glass window. A LoveLace nebulizer with a nominal droplet size of 7 micrometers was used to generate fluorescent monodisperse polystyrene latex aerosols 0.5, 1, 2, and 3 micrometers in diameter. A Vilnius aerosol generator was used to generate fluorescent PSL dry powders 6 micrometers in diameter. The generated aerosols were collected on 37 mm polyvinyl chloride filters positioned after the impactors. Sample fluorescence was determined using a GloMax-Multi Jr fluorometer. Impactor efficiencies at the various sizes were used to construct the collection curves of impactors. Efficiency curves were subsequently superimposed on the cyclone efficiency curve to obtain the final efficiencies of the sampling devices. The results indicated that the cut-off diameters increased with impactor jet size. The new efficiency curves of the sampling devices had similar shapes to actual alveolar deposition as determined experimentally in human subjects. Actually they fell between actual alveolar deposition curves 2 and 4 seconds for mean residence times. The findings from this work can be applied to design a novel respirable dust sampler that provides a realistic estimate of pulmonary deposition to be used in dose- response relationships for the various mineral dusts encountered in general and mining industries. The under estimation of the dust toxicity associated with the current sampling methodology may be one of the reasons for continuous lowering of the TLV and PEL for silica.

The purpose of this research is to demonstrate the ability to generate and characterize a nanometer sized aerosol using solutions, suspensions, and a bulk nanopowder, and to research the viability of using an acoustic dry aerosol generator/elutriator (ADAGE) to aerosolize a bulk nanopowder into a nanometer sized aerosol. The research compares the results from a portable scanning mobility particle sizer (SMPS) to the more traditional method of counting and sizing particles on a filter sample using scanning electron microscopy (SEM). Sodium chloride aerosol was used for the comparisons. The sputter coating thickness, a conductive coating necessary for SEM, was measured on different sizes of polystyrene latex spheres (PSLS). Aluminum oxide powder was aerosolized using an ADAGE and several different support membranes and sound frequency combinations were explored. A portable SMPS was used to determine the size distributions of the generated aerosols. Polycarbonate membrane (PCM) filter samples were collected for subsequent SEM analysis. The particle size distributions were determined from photographs of the membrane filters. SMPS data and membrane samples were collected simultaneously. The sputter coating thicknesses on four different sizes of PSLS, range 57 nanometers (nm) to 220 nm, were measured using transmission electron microscopy and the results from the SEM and SMPS were compared after accounting for the sputter coating thickness. Aluminum oxide nanopowder (20 nm) was aerosolized using a modified ADAGE technique. Four different support membranes and four different sound frequencies were tested with the ADAGE. The aerosol was collected onto PCM filters and the samples were examined using SEM. The results indicate that the SMPS and SEM distributions were log-normally distributed with a median diameter of approximately 42 nm and 55 nm, respectively, and geometric standard deviations (GSD) of approximately 1.6 and 1.7, respectively. The two methods yielded similar distributional trends with a difference in median diameters of approximately 11 - 15 nm. The sputter coating thickness on the different sizes of PSLSs ranged from 15.4 - 17.4 nm. The aerosols generated, using the modified ADAGE, were low in concentration. The particles remained as agglomerates and varied widely in size. An aluminum foil support membrane coupled with a high sound frequency generated the smallest agglomerates. A well characterized sodium chloride aerosol was generated and was reproducible. The distributions determined using SEM were slightly larger than those obtained from SMPS, however, the distributions had relatively the same shape as reflected in their GSDs. This suggests that a portable SMPS is a suitable method for characterizing a nanoaerosol. The sizing techniques could be compared after correcting for the effects of the sputter coating necessary for SEM examination. It was determined that the sputter coating thickness on nano-sized particles and particles up to approximately 220 nm can be expected to be the same and that the sputter coating can add considerably to the size of a nanoparticle. This has important implications for worker health where nanoaerosol exposure is a concern. The sputter coating must be considered when SEM is used to describe a nanoaerosol exposure. The performance of the modified ADAGE was less than expected. The low aerosol output from the ADAGE prevented a more detailed analysis and was limited to only a qualitative comparison. Some combinations of support membranes and sound frequencies performed better than others, particularly conductive support membranes and high sound frequencies. In conclusion, a portable SMPS yielded results similar to those obtained by SEM. The sputter coating was the same thickness on the PSLSs studied. The sputter coating thickness must be considered when characterizing nanoparticles using SEM. Finally, a conductive support membrane and higher frequencies appeared to generate the smallest agglomerates using the ADAGE technique.

Veterinarians routinely conduct surgical operations on animals while veterinary technicians administer anesthetic gas to sedate the animal prior to an operation. One commonly used anesthetic agent in veterinary clinics is isoflurane. Veterinary workers have the potential to be exposed to this gas during surgical operations. The Occupational Safety and Health Administration (OSHA) does not have a specific Permissible Exposure Limit (PEL) for isoflurane, however The National Institutes for Health (NIH) does advise that workers should not be exposed to isoflurane in concentrations exceeding 2 parts per million (ppm) for an 8 hour Time Weighted Average (TWA). Animal clinics vary in the amount of surgeries they perform. Some clinics specialize in surgical services and therefore conduct a high volume of surgeries, while others that perform general practice work may conduct a far lower volume of surgeries. The research objectives for this study were to determine if veterinary workers are exposed to isoflurane levels above the concentration recommended by NIH and to quantify any disparity that exists between worker exposures at two veterinary facilities. A portable infrared ambient air analyzer (Miran SapphIRe, XL, ThermoScientific) was used to measure area concentrations of isoflurane and sorbent tube sampling via OSHA Method 103 was used to determine personal exposures to isoflurane. For the three days that sampling took place at the low volume clinic, personal sampling (samples taken in the breathing zone of a worker) during surgery showed that isoflurane concentrations exceeded the NIOSH recommended limit for 3 of the 5 samples when assuming a 6-hour gas exposure. When assuming exposure only lasted for the 2 hours that sampling occurred, 1 of the 5 samples exceeded the NIOSH recommended limit. For the three days that sampling was conducted at the high volume clinic, none of the 6 samples taken exceeded the NIOSH recommended exposure limit. The average isoflurane exposure to workers at the high volume clinic was 1.72 ppm while the average for the low volume clinic was 3.77 ppm. The average isoflurane exposure for veterinarians was 2.05 ppm and the average for veterinary technicians was 3.16 ppm. These data provide evidence that veterinary technicians may face higher exposures to isoflurane gas than veterinarians. There is also evidence that workers at the low volume clinic may be exposed to greater concentrations of isoflurane than workers at the high volume clinic. The average isoflurane concentrations were lower for the high volume clinic likely due to the fact that they relied only on an injectable sedative and no delivery of anesthetic gas for most operations. The high volume clinic also used more sophisticated equipment than the low volume clinic for the capture of waste gases.

This dissertation used an experience sampling design to examine effects of experienced workplace incivility from three categories of organizational insiders (coworkers, supervisors, and physicians) and from organizational outsiders (patients and their visitors) on targets' emotions, burnout, physical symptoms, and their own uncivil behaviors toward each of the four groups of people. Data were collected from 75 nurses with each nurse responding to online surveys twice per week for 5 consecutive weeks. Results from hierarchical linear modeling showed that within individuals, negative emotions were positively associated with experienced workplace incivility (overall and source-specific), burnout was positively associated with overall workplace incivility and incivility from coworkers, and that physical symptoms were positively associated with experienced workplace incivility from supervisors. In addition, within individuals overall and source-specific experienced workplace incivility all positively predicted targets' own uncivil behaviors correspondingly. None of the proposed moderating effects of three between-person level personality traits (emotional stability, hostile attribution bias, and emotional competence) were supported, and the only significant moderating effect found was that emotional stability moderated the relationship between experienced workplace incivility from- and targets' own uncivil behaviors toward- supervisors was opposite to the prediction. Further, both violence prevention climate and civility climate showed main effects in negatively predicting participants' own uncivil behaviors, but only violence prevention and two of its dimensions (policies and procedures, and pressure for unsafe practices) buffered some of the negative effects of experienced workplace incivility. In summary, the current study found that within individuals experienced workplace incivility had negative effects on targets' emotions, well-being, and behaviors, and that perceived violence prevention climate buffered some of the negative effects.

Abstract not available

In spite of the substantial repository of literature about respirators, little is known about the practicalities of their use. The focus of this research was about the practical aspects of using respirators in New South Wales workplaces. Two self-administered postal surveys were used to assess the level of implementation of respirator programs in 1996 and 2001. After five years, six elements improved. The most improvement was seen in the area of documentation including written procedures, keeping training records, recording respirator tasks, and maintenance records. The second survey investigated respirator maintenance and found little automated cleaning. Thorough washing was scarce with more than 50% of organisations relying on moist towelettes. For the third portion of the research methodology 485 used, half facepiece reusable respirators from 36 different sites were examined to determine the most common respirator defects. Maintenance and cleaning procedures were primitive and probably inadequate. Disinfection or sanitisation was common practice indicating concern about infectious diseases. The 2001 survey found that physical inspection of respirators in the workplace usually checked for the common types of defects found in the examination of used respirators. Weight, breathing resistance, heat and tightness were reported as causes of discomfort. The key outcomes from the research were that respirator programs were poorly implemented in a group of organisations that were expected to have more expertise than most and that the most common defects could be corrected by good respirator cleaning programs. / Doctor of Philosphy (PhD)

This thesis covers sampling and analytical procedures for isocyanates (R-NCO) and amines (R-NH2), two kinds of chemicals frequently used in association with the polymeric material polyurethane (PUR). Exposure to isocyanates may result in respiratory disorders and dermal sensitisation, and they are one of the main causes of occupational asthma. Several of the aromatic diamines associated with PUR production are classified as suspected carcinogens. Hence, the presence of these chemicals in different exposure situations must be monitored. In the context of determining isocyanates in air, the methodologies included derivatisation with the reagent di-n-butylamine (DBA) upon collection and subsequent determination using liquid chromatography (LC) and mass spectrometric detection (MS). A user-friendly solvent-free sampler for collection of airborne isocyanates was developed as an alternative to a more cumbersome impinger-filter sampling technique. The combination of the DBA reagent together with MS detection techniques revealed several new exposure situations for isocyanates, such as isocyanic acid during thermal degradation of PUR and urea-based resins. Further, a method for characterising isocyanates in technical products used in the production of PUR was developed. This enabled determination of isocyanates in air for which pure analytical standards are missing. Tandem MS (MS/MS) determination of isocyanates in air below 10-6 of the threshold limit values was achieved. As for the determination of amines, the analytical methods included derivatisation into pentafluoropropionic amide or ethyl carbamate ester derivatives and subsequent MS analysis. Several amines in biological fluids, as markers of exposure for either the amines themselves or the corresponding isocyanates, were determined by LC-MS/MS at amol level. In aqueous extraction solutions of flexible PUR foam products, toluene diamine and related compounds were found. In conclusion, this thesis demonstrates the usefulness of well characterised analytical procedures and techniques for determination of hazardous compounds. Without reliable and robust methodologies there is a risk that exposure levels will be underestimated or, even worse, that relevant compounds will be completely missed.