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Face velocity is the standard variable used to test the performance of laboratory fume hoods. A quantitative testing method developed by Caplan & Knutson involves the measurement of tracer gas leakage out of a hood. Use of that method identified parameters other than face velocity that seemed to affect hood performance. In this study, a new testing method (Scott Method) was developed to incorporate hood parameters identified by Caplan & Knutson with face velocity measurements to generate a more comprehensive hood performance test method. The Scott Method consists of a semi-quantitative rating scheme that assesses the effects of traffic, diffuser velocity, equipment in the hood, and variation in face velocity on hood performance. The performance of 10 laboratory fume hoods was measured by the three methods; the Caplan & Knutson method was used as the measurement standard. The study hypothesis was that the Scott Method would yield a better prediction of hood performance than face velocity alone. This study suggests that prediction of hood performance by the Scott Method was not significantly improved relative to the use of face velocity alone.

Thesis (M.P.H.(Occupational Hygiene)), Faculty of Health Sciences,University of the Witwatersrand, 2009 / This study was aimed at describing the nature of Occupational Health and Safety (OHS) inspections and blitzes conducted in the Port Elizabeth Integrated Department of Labour (DoL) in 2005, the nature and number of prohibitions, contraventions, as well as improvement notices issued. The objectives were to determine the number of OHS inspections conducted in the Port Elizabeth Labour Centre (PELC) in 2005; to describe the nature of the inspections and the type of industries inspected in the PELC in 2005; and to determine the frequency and nature of prohibitions, contraventions and improvement notices issued. The data was obtained from the PELC. The results of the study revealed that the inspectorate conducted a total of 1258 and this exceeded the target of 800 OHS inspections for the PELC. However, it is questionable how this target was developed. The target is not representative and does not give an overall picture of conditions in the workplace. The results indicated that inspectors were not competent in conducting boiler inspections as well on Major Hazardous Installation (MHI) since none of these inspections were conducted. On the inception of the OHS task team, there was a sudden increase in inspections conducted in the construction industry in October 2005 as well as the rate of finalisation of incidents in November 2005 and this was attributed to the fact that they were not conducting inspections on other labour laws and were only focusing on OHS. An assessment of the inspectors’ inspection checklists revealed that the inspections were being reduced to just a yes or no tick exercise, with no recommendation on appropriate action to be taken by the employer. It became evident that the inception of a special team in September 2005 contributed to an increased number of OHS inspections, since they were only focusing on OHS issues. This team ensured that in November 2005 there were 43 incidents finalised as compared to the 101 finalised over 11 months. They also ensured that a total of 258 OHS inspections were conducted from September 2005 to December 2005. Although these inspectors were not fully competent in addressing health and s afety issues their momentary focus on OHS activities ensured that they made a difference in the rate of finalisation of incidents. However, when some of the cases were taken to court no successful prosecution could be obtained because there are no OHS focused prosecutors, which have a clear understanding of Act. Discussions with the inspectors revealed that there was a lack of morale and loss of interest in their work, thus causing them not to put in much effort. These discussions revealed that this lack of morale was caused by the frustrations they often experienced in the execution of their duties due to lack of training as well as lack of cooperation from the employers. Furthermore, the inspectors revealed that the great number of resignations from inspectors who were leaving for greener pastures left them with a lot of work with no financial incentive. It also became apparent that there was no objective strategy underlying the number of inspections required relative to the purpose of the inspections, taking into account the nature and complexity of the industry that is to be inspected. The failure of the Service Delivery Unit to give a direction on how qualitative inspections should be measured demoralised them because the focus was only on the quantity (240 inspections per annum) of inspections that are to be conducted by each inspector. It is recommended that training, which should include a proper career path be conducted for inspectors to improve the inspectors’ capability and to motivate them. Strong relations with the South African Police Services and the Department of Justice should be promoted to ensure effectiveness of service delivery. These relations will ensure that inspectors are readily assisted by the police when they deal with uncooperative employers. Training of prosecutors will ensure that they understand the OHSA and its implementation and therefore effectively defend cases that are taken to court. The targets set for inspections should be scientifically supported and take into account the nature and complexity of the production processes. Lastly, revision of salary packages should be looked into to ensure retention of competent staff. The above recommendations will only be effective if the Business Unit Manager and the Regional Manager address them through the National Department of Labour since their implementation will affect all inspectors.

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The objectives of this study were: (1) to compare lung fibre concentration and dimensions found in two groups of former Quebec chrysotile miners (Asbestos and Thetford-Mines) and, (2) to investigate the relationship between lung-retained mineral fibre concentration and dimension (length, diameter, and aspect ratio) to severity of interstitial lung fibrosis (asbestosis) within these groups. / Lung fibre content was determined for 86 former employees of chrysotile mines and mills in two Quebec mining regions: Thetford-Mines and Asbestos (Jeffrey Mine). Six lung samples were selected for each subject from predetermined intrapulmonary sites. / In summary, the concentrations of tremolite for short (<5 mum) intermediate-length (5--10 mum) and long (>10mum) fibres were 4, 2, and 2 fold higher respectively among workers of Thetford-Mines than those from Asbestos. These differences were statistically significant between the two groups (p < 0.05 for all tremolite size categories). No consistent and biologically important difference was found among fibre dimensions in any of the size categories (p > 0.1 for all fibre types and size categories). These observations suggested that the much higher exposure in Thetford-Mines to asbestos fibres, tremolite fibres being more apparent, is the most plausible factor which may explain the higher incidence of lung diseases among the former miners and millers of Thetford-Mines. / Concentration of short (<5 mum) tremolite fibres was the best predictor of asbestosis severity in both mining groups (r = 0.44, p < 0.01 and r = 0.39 p < 0.01 for Thetford-Mines and Asbestos, respectively). Chrysotile fibre concentration showed a lower correlation with asbestosis severity among subjects from Thetford-Mines (r = 0.28, p < 0.1 and r = 0.39, p < 0.01 and for fibres <5 mum and fibres 5--10 mum respectively). Long (>10 mum) amosite fibre concentrations showed a linear relationship with asbestosis severity in the group of miners and millers from Asbestos (r = 0.5, p < 0.01). Shorter commercial amphibole concentrations did not show this relationship and these fibres were largely absent from the lungs of miners from Thetford-Mines. Concentration of asbestos bodies from lung digests was significantly associated with fibrosis for subjects from Thetford-Mines only (r = 0.3, p = 0.05). (Abstract shortened by UMI.)

Two subject groups, seven PPS (4 males, 3 females) and 15 normal controls (9 females, 6 males) were matched on the basis of age, height and weight and participated in this study. Three repeated measurements were conducted to evaluate the reliability of isokinetic measurement of strength (at 4 velocities) and fatigability (25 reciprocal contractions at 3.14 rads.s$ sp{-1}$). Data from two subsequent test days were used to evaluate the fatigue responses of the PPS subjects while ON or OFF pyridostigmine. Significant strength differences were seen between the two groups, however there was no observed difference in the rate of development of fatigue. Reliability of strength was demonstrated for the knee extensors and flexors of the PPS subjects after three consecutive test days. Fatigability of the knee extensors in PPS subjects could be tested reliably after three test days but more time would be required for reliable performance of the knee flexors. Reliability of strength and fatigability was seen for both the knee extensor and flexors of the normal controls after only two consecutive test days. A beneficial effect of the drug on fatigability was not seen in the three female PPS subjects, but was demonstrated in one male subject. The drug appeared to have a beneficial effect on strength in the remaining three male subjects.

It is accepted that material handling is an activity presenting a high risk for injury, particularly to the back. In this study, an observation strategy has been developed and validated in order to evaluate the presence of these risky conditions while performing a handling task. Moreover, certain future utilisation conditions were specified. / Fifty-one observation variables were identified and an observation structure was elaborated from three data sources. These sources were: a literature review on observation grids, interviews with expert handlers and video sequences of a laboratory manual handling study where 10 inexperience subjects performed a total of 1500 container transfers. Observational data entry was recorded from a sample of these 174 sequences for which biomechanic measures were also done. / The results show that observations can be reliable and valid and that the diversity of observation objects can be important and extend beyond postural variables. The observations performed on an uninterrupted video sequence are the ones that present the most difficulties. The observers' experience does not seem to be an important factor in obtaining reliable results. On the other hand, the observation criteria, the training and the breakdown of variable classes are factors susceptible to influence reliability. / Many observation variables for balance had a significative impact on the biomechanical measure of balance, particularly when the object is taken and put down. This is the case with the number of foot supports, the weight distribution at the base of support and the position of the object, especially it's lateral deportation with respect to the body. The backward movement of the pelvis, which enables to compensate for the added external weight to the body, was significantly associated to balance. In general grouped variables, have more impact on the measure of balance than variables taken individually. Grouped variables are also less prone to variations when handling contexts are changed. For asymmetry, shoulder orientation with respect to the pelvis, back flexion, parallelism of the shoulders to the ground, and the position of the hands on the object handled all had a significative impact on the effort asymmetries when the object was taken from the plate-form. For the control and fluidity, a difficulty in finding a corresponding biomechanical measure or reliability problems did not enable us to verify whether our observations could have permitted to evaluate the risky conditions. (Abstract shortened by UMI.)

This study addressed the question of silica exposure, silicosis, and lung cancer in respect of lung particle burden. Sixty seven paraffin-embedded lung tissue samples of silicotic gold miners (39 non-lung cancer (NLC-SI) and 28 lung cancer (LC-SI)), were analyzed by transmission electron microscopy and energy dispersive X-ray spectroscopy for angular particles and fibres/cleavage fragments. Crystalline silica was characterized by X-ray powder diffraction on silver membrane filter. / Results indicated that both silicotic groups had non-significantly different concentrations and sizes of all particle types except quartz. Indeed, the NLC-SI group had a higher concentration of quartz than the LC-SI (3.77 $ mu$g/mg dry lung tissue compared to 2.47 $ mu$g/mg, p = 0.006, Mann-Whitney test). After adjusting for the differences in age at death, silicosis severity, and other dust exposure variables, but not for unknown smoking habit, the NLC-SI group still had a higher, through statistically non-significant, quartz concentration than did the LC-SI group (3.34 and 2.35 $ mu$g/mg respectively, p = 0.106, ANCOVA). This pattern was in good agreement with a pattern of a higher silicosis severity score in the NLC-SI group. The calendar year of first exposure was a prime determinant of lung burden of total particles, silica, and clay, with the coefficients of determination $ rm (R sp2)$ of 11-15%. A significant correlation between the concentrations of silica particles and quartz was observed, although quartz was the only significant predictor of the silicosis severity in the gold miners $ rm (p < 0.001, R sp2 = 20.5 %).$ A significant correlation between quartz concentration and the year interval since last exposure to death (r = + 0.25, $ rm p < 0.05)$ suggested a possibility of impaired lung clearance of quartz. Years of dust exposure did not show a significant linear relationship with any types of lung particles. The very low asbestos concentrations detected in only a small number of cases ruled out the suspicion of asbestos as a confounder of lung cancer in the miners. In conclusion, this study of lung concentration of quartz and other minerals did not support the association of silica, silicosis, and lung cancer.

A comparison was made between NIOSH-type, prepacked nutshell charcoal tubes and layers of commercial charcoal cloth in a stainless steel cassette designed for the active sampling/adsorption of different concentrations of a mixture of volatile organic chemicals (VOCs) (benzene, trichloroethylene, toluene, tetrachloroethylene, chlorobenzene and o-xylene). Physicochemical parameters of the charcoal cloth including breakthrough times and volumes and adsorption capacities were determined for toluene and the VOC mixture. The quantitative removal of VOCs from the charcoal cloth by solvent desorption, by supercritical fluid extraction (SFE), and by thermal desorption was studied prior to analysis by gas liquid chromatography with photoionization detection. Optimal conditions were explored both in laboratory and industrial environments. / Charcoal cloth was comparable to the NIOSH tube, adsorbed VOCs being quantitatively removed at any time up to 32 days after sampling. Although solvent (pentane, hexane) desorption yielded accurate, reproducible results with a high percent recovery of the VOCs, a major disadvantage was the irreparable damage done to the cloth, preventing its repeated use. Desorption by SFE proved unreliable for these low molecular weight VOCs, both the collecting solvents and the VOCs being lost during extraction. Thermal desorption proved to be efficient, sensitive and reliable, repeated heating having no effect on the adsorptive properties of the cloth. Charcoal cloth would appear to be a useful adsorbing medium for air sampling of both industrial and office building/home environments for either single chemicals or mixtures.