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No description available.

No description available.

No description available.

Diesel particulate matter (DPM) is comprised of two main fractions, organic carbon (OC) and elemental carbon (EC). DPM is the solid portion of diesel exhaust and particles are submicron in size typically ranging from 10 to 1000 nanometers. DPM is a known respirable hazard and occupational exposure can lead to negative health effects. These effects can range from irritation of the eyes, nose, and throat to more serious respirable and cardiovascular diseases. Due to the use of diesel powered equipment in confined airways, underground mine environments present an increased risk and underground mine works can be chronically overexposed. Current engineering controls used to mitigate DPM exposure include cleaner fuels, regular engine maintenance, ventilation controls, and enclosed cabs on vehicles. However even with these controls in place, workers can still be overexposed. The author's research group has previously tested the efficacy of a novel, fog-based scrubber treatment for removing DPM from the air, in a laboratory setting. It was found that the fog treatment improved DPM removal by approximately 45% by number density compared to the control trial (fog off). The previous work stated thermal coagulation between the fog drops and the DPM, followed by gravitational settling of the drops to be the likely mechanisms responsible for the DPM removal. The current work investigated the efficacy of the fog treatment on a larger scale in an underground mine environment, by using a fogging scrubber to treat the entire exhaust stream from a diesel vehicle. A total of 11 field tests were conducted. Based on measurements of nanoparticle number concentration at the inlet and outlet of the scrubber, the fog treatment in the current work showed an average improvement in total DPM removal of approximately 55% compared to the control (fog off) condition. It was found that the treatment more effectively removed smaller DPM sizes, removing an average of 84 to 89% of the DPM in the 11.5, 15.4, and 20.5 nanometer size bins and removing 24 to 30% of the DPM in the 88.6, 115.5, and 154 nanometer size bins. These observations are consistent with expectations since the rate of coagulation between the DPM and fog drops should be greater for smaller diameters. Further analysis of the DPM removal was aided by the development of a mechanistic model of the fogging scrubber. The model uses the inlet data from the experimental tests as input parameters, and it outputs the outlet concentration of DPM for comparison to the experimental outlet data. Results provided support for the notion that DPM removal relies on DPM-fog drop coagulation, and subsequent removal of the DPM-laden drops as opposed to DPM removal by diffusion or inertial impaction of DPM directly to the walls. The model results suggest that inertial impaction of these drops to the scrubber walls is likely much more important than gravitational settling. Moreover, the ribbed geometry of the tubing used for the scrubber apparatus tested here appears to greatly enhance inertial impaction (via enhancement of depositional velocity) versus smooth-walled tubing. This is consistent with previous research that shows particle deposition in tubes with internally ribbed or wavy structures is enhanced compared to deposition in tubes with smooth walls. / Master of Science / Diesel particulate matter (DPM) describes the solid portion of diesel exhaust. These particles are in the nanometer size range (10-1000nm) and can penetrate deep within the lungs presenting a serious health hazard. Because of the use of diesel powered equipment in confined spaces, DPM presents an occupational hazard for underground mine workers. Even with the use of cleaner fuels, regular engine maintenance, proper ventilation, and enclosed vehicle cabs, workers can still be over exposed. Previous work has shown that a water fog treatment can help to remove DPM from the air in a laboratory setting. This removal is due to the DPM particles attaching to the drops, followed by the drops settling out of the air due to gravity or impacting the walls of a tube. To explore a full scale exhaust treatment, a fogging scrubber was built using a fogger and a long tube, and was tested in an underground mine on vehicle exhaust. Experimental results showed that the fog treatment was effective at removing DPM from the exhaust. On average, the fog improved DPM removal by about 55% compared to when the treatment was not employed (fog off). To better understand the mechanisms responsible for DPM removal in the scrubber, a computer model was generated. The model uses the inlet parameters from the field tests, such as inlet DPM and fog concentration and tube geometry, and predicts the scrubber outlet DPM concentration. The model results suggest that the primary way that DPM is removed from the system is by combining with fog drops, which then hit the scrubber tube walls. This effect is probably enhanced by the ribbed structure of the scrubber tubing used here, which may be important for practical applications.

Background: Workers are daily exposed to diesel exhaust (DE) and DPM due to the continuous increase of diesel–powered vehicles in the underground mining environment. The National Institute for Occupational Safety and Health (NIOSH) recommends that DE be regarded as a “potential occupational carcinogen”. A great concern in the South African mining industry is that there is currently no existing occupational exposure limits (OEL) for DPM. Aim: To quantify the exposure of workers to DPM (that consists out of total carbon (TC): which is a combination of elemental carbon (EC) and organic carbon (OC)) in the ambient air of underground working environments. Also to compare different occupations exposure levels to an international standard (the Mine Safety and Health Administration’s (MSHA) OEL for TC) as South Africa has no proposed guideline or standard for occupational exposure to DPM and finally to determine whether or not occupations working at mines with different mining methods have different exposure levels to DPM. Methodology: Workers personal exposure to DPM was monitored using the NIOSH 5040 method. A DPM sampler that consisted of a cyclone, a pre–packed SKC filter cassette (37 mm) with impactor, tubing, label clips and a sampling pump was used. The flow rate was calibrated at 2.0 litres per minute (L/min) for the sampling of sub–micrometer particles. The personal sampler device was attached to the employee’s breathing zone for the duration of the work shift (normal eight–hour time–weighted average (TWA) standard). A high risk group (workers operating diesel–powered vehicles), a low risk group (workers working in the same mine, sharing the same supplied air, but not operating these vehicles) and a control group (workers working at a different mine with a different mining method) was monitored. The exposure levels were evaluated and compared with the specific OEL mentioned previously. Results: For the purpose of this study, TC exposure results were evaluated and not EC or OC. All the occupations within their specific exposure group was exposed to TC. When the control group’s exposures were compared with the high and low risk group exposures, a significant difference was recorded (p–value = 0.0001). However when the high and low risk exposures were compared with each other, no difference was recorded (p–value = 0.4405). When the results of the various groups were compared with the MSHA OEL all the occupations from the high and low risk group’s results were above the OEL, but only one occupation from the control group exceeded the OEL. Conclusion: It should be noted that all the occupations no matter the mining method / mine was exposed to TC. The high and low risk exposure groups was however much higher than the control group and a continues monitoring programme should be implemented for these exposure groups. Their results exceeded the OEL, where the control group had much lower exposure levels and only one occupation exceeded the OEL. Greater focus should be given to the mechanized mining occupations since diesel–powered vehicles are used to perform their core mining needs whereas at the conventional mine the use of these vehicles are limited. Recommendation: Depending on the different occupations sampled various engineering controls can be considered. Some include diesel oxidation catalysts (DOC), diesel particulate filters (DPF) and diesel disposable exhaust filters (DEF) or also known as disposable diesel exhaust filters (DDEF) which is very effective in removing DPM from the exhaust of dieselpowered equipment. Education and training are also critical components to the success of a diesel emission management programme and the last resort to be considered is the appropriate personal protective equipment (PPE). South Africa should consider the implementation of national standards in order to monitor the progress and success of the diesel emission management programme implemented. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2012.

Background: Workers are daily exposed to diesel exhaust (DE) and DPM due to the continuous increase of diesel–powered vehicles in the underground mining environment. The National Institute for Occupational Safety and Health (NIOSH) recommends that DE be regarded as a “potential occupational carcinogen”. A great concern in the South African mining industry is that there is currently no existing occupational exposure limits (OEL) for DPM. Aim: To quantify the exposure of workers to DPM (that consists out of total carbon (TC): which is a combination of elemental carbon (EC) and organic carbon (OC)) in the ambient air of underground working environments. Also to compare different occupations exposure levels to an international standard (the Mine Safety and Health Administration’s (MSHA) OEL for TC) as South Africa has no proposed guideline or standard for occupational exposure to DPM and finally to determine whether or not occupations working at mines with different mining methods have different exposure levels to DPM. Methodology: Workers personal exposure to DPM was monitored using the NIOSH 5040 method. A DPM sampler that consisted of a cyclone, a pre–packed SKC filter cassette (37 mm) with impactor, tubing, label clips and a sampling pump was used. The flow rate was calibrated at 2.0 litres per minute (L/min) for the sampling of sub–micrometer particles. The personal sampler device was attached to the employee’s breathing zone for the duration of the work shift (normal eight–hour time–weighted average (TWA) standard). A high risk group (workers operating diesel–powered vehicles), a low risk group (workers working in the same mine, sharing the same supplied air, but not operating these vehicles) and a control group (workers working at a different mine with a different mining method) was monitored. The exposure levels were evaluated and compared with the specific OEL mentioned previously. Results: For the purpose of this study, TC exposure results were evaluated and not EC or OC. All the occupations within their specific exposure group was exposed to TC. When the control group’s exposures were compared with the high and low risk group exposures, a significant difference was recorded (p–value = 0.0001). However when the high and low risk exposures were compared with each other, no difference was recorded (p–value = 0.4405). When the results of the various groups were compared with the MSHA OEL all the occupations from the high and low risk group’s results were above the OEL, but only one occupation from the control group exceeded the OEL. Conclusion: It should be noted that all the occupations no matter the mining method / mine was exposed to TC. The high and low risk exposure groups was however much higher than the control group and a continues monitoring programme should be implemented for these exposure groups. Their results exceeded the OEL, where the control group had much lower exposure levels and only one occupation exceeded the OEL. Greater focus should be given to the mechanized mining occupations since diesel–powered vehicles are used to perform their core mining needs whereas at the conventional mine the use of these vehicles are limited. Recommendation: Depending on the different occupations sampled various engineering controls can be considered. Some include diesel oxidation catalysts (DOC), diesel particulate filters (DPF) and diesel disposable exhaust filters (DEF) or also known as disposable diesel exhaust filters (DDEF) which is very effective in removing DPM from the exhaust of dieselpowered equipment. Education and training are also critical components to the success of a diesel emission management programme and the last resort to be considered is the appropriate personal protective equipment (PPE). South Africa should consider the implementation of national standards in order to monitor the progress and success of the diesel emission management programme implemented. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2012.

In der vorliegenden Arbeit werden Al2O3-geträgerte Eisenoxid-Katalysatoren auf ihre Eignung in der Nachbehandlung von Dieselabgasen getestet. Hierbei werden die Oxidationsreaktionen von Kohlenmonoxid, Propen, Stickstoffmonoxid sowie Ammoniak getestet. Weiterhin wird die Katalysatoraktivität bei der Stickoxidminderung nach dem SCR-Verfahren untersucht. Basierend auf einer detaillierten Charakterisierung wird eine Struktur-Aktivitäts-Korrelation entwickelt, auf deren Basis ein Verständnis für die Art der aktiven Zentren solcher Katalysatoren generiert wird. Zudem wird ein Modell entwickelt, mit Hilfe dessen die spezifische Aktivität der verschiedenen Typen an aktiven Zentren bewertet werden kann. Darüber hinaus wird in dieser Arbeit auf die Stickoxidminderung nach dem SCR-Verfahren fokussiert, was die Untersuchungen des Reaktionsmechanismus sowie die Struktur-Aktivitäts-Korrelation an hydrothermal gealterten Katalysatoren beinhaltet.

Os ácidos anacárdicos (AAs) provenientes do líquido da casca da castanha de caju têm propriedades antioxidantes e anti-inflamatórias. Seus efeitos são bem estabelecidos em vários sistemas in vitro, no entanto não há publicações a respeito de suas ações no tecido pulmonar. No presente estudo, foram analisados os efeitos da suplementação dos AAs em modelo de inflamação subaguda induzida pelas partículas resultantes da combustão do diesel (DEP) em camundongos. Camundongos BALB/c machos receberam por 20 dias consecutivos instilação intranasal de 50 g DEP diluídos em 10 L de salina. Como pré-tratamento, 10 dias antes do ínicio da instilação intranasal com DEP, os animais foram tratados por via oral com 50, 150 ou 250 mg/kg de AAs diluídos em 100 L de óleo da castanha de caju ou apenas 100 L de óleo da castanha de caju (veículo). Foram analisados: a densidade de células inflamatórias, as células imunomarcadas para TNF-, NF-B e KC e a área imunomarcada para 8-isoprostano no parênquima pulmonar. Além disso, foi mensurado o perfil celular e de citocinas no LBA e a área imunomarcada por VCAM e KC nos vasos peribronquiolares. As atividades das enzimas antioxidantes GR, GPx, GST e CAT foram analisadas no tecido pulmonar e no sangue periférico. O tratamento com os AAs foram capazes de agir como substâncias protetoras no parênquima pulmonar. A dose de 50 mg/kg demonstrou efeitos mais proeminentes na redução dos marcadores de inflamação pulmonar, no entanto as três doses foram capazes de atuarem como substâncias antioxidantes aumentando a atividade das enzimas antioxidantes e reduzindo a expressão de VCAM nos vasos pulmonares na presença da sobrecarga oxidativa induzida pelas DEP. Portanto, os AAs demonstraram ter potencial preventivo contra os efeitos das DEP no sistema respiratório, atuando como substâncias naturais com propriedades anti-inflamatórias e antioxidantes / Anacardic acids (AAs) from cashew nut shell liquid have important antioxidant properties. However despite their well established effects in several systems in vitro, there were no reports about their effects in lung tissue. In this present study, we examined the effects of AAs supplementation in a model of low diesel exhaust particles (DEP) induced lung inflammation in mice. Male BALB/c mice received intranasal instillation of 50 g DEP diluted in 10 L of saline solution during 20 days. Ten days before instillation, animals were oral treated by the following 30 days with 50, 150 or 250 mg/Kg AAs diluted in 100 L of cashew nut oil (CNO) or vehicle (100 L of CNO). In order to evaluate anti-inflammatory and antioxidant effects, we analyzed the influx of inflammatory cells, TNF-, NF-B and KC positive cells; and the expression of 8-isoprostane in alveolar parenchyma. In addition, we measured the cellular profile and cytokines level in BALF and the VCAM and KC expressions in peribronchiolar pulmonary vessels.The activities of antioxidant enzymes GR, GPx, GST and CAT were analyzed by spectrophotometric method to assessing oxidative status in the lung tissue and in the peripheral blood. Treatment with AAs was able to act as a protective substance in lung tissue. The dose of 50 mg/kg showed more prominent effects in decreasing the inflammatory markers caused by DEP, however all the three doses are able to preserve antioxidant enzymes activities in the presence of oxidative charge and decreased the expression of VCAM in vessels. Furthermore, we demonstrated that AAs, which are natural substance, have potential effects against air pollution-related effects in respiratory system, acting as anti-inflammatory and antioxidant properties

Diss. (sammanfattning) Umeå : Umeå universitet, 2009. / Härtill 5 uppsatser. Även tryckt utgåva.