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INTRODUCTION According to ILO (2000), in developing countries about 59 per cent of labour force belongs to the agriculture sector. This is a particularly serious concern from the viewpoint of promoting the health of a population and reduction of social vulnerability in a country like Mozambique where more than half of the population depends on agriculture as their means of survival and wage earning. The current study attempts to address the agriculture mineral dust as occupational hygiene and health risk factors among agriculture workers, taking into account that dust that is breathed in may contain quartz, known as a carcinogenic and pathogenic agent. OBJECTIVE OF THE STUDY The study aims to pinpoint risk potential to health that may be caused by mineral dust through assessing occupational exposure doses to respirable dust and quartz during plowing, and primary and secondary tilling operations identified in the study, as the major dust risk operations; and the more prevailing operations in maize and root plant on medium sized farms‟ production cycle. MATERIALS AND METHODS Sampling of dust was conducted on 2 medium sized farms selected by convenience in the district of Boane (study setting) based on geological map soil characterisation of the study area. Full-time period dust samples were collected from 4 different tractor operators. The tractor operators were identified as the risky group. In total were taken seventy valid samples; thirty-nine from maize and thirty-one from root plant. Three tractor operators were fully engaged in maize cultivation and 1 was engaged in root plant during the period of the study data collection. In all occasions, the „open-cabbed‟ tractor machines were observed and used by tractor operators. The involved sampling subjects‟ operators were informed in advance about the study purpose and they accepted participation in the research. Nineteen dust samples were randomly selected for determination of the quartz fraction using the MDHS 101 Infrared Spectrophotometer Method. Active dust sampling MDHS 14/3 HD-cyclone method was applied with GLA 5000 filter type. All quality control procedures applied in active dust sampling method and gravimetric determination of concentration were checked in order to accept or reject samples for further analysis and determination of exposure concentration. RESULTS Standard statistical procedures and sampling strategy data analysis and interpretation procedures, including the SPSS software version 11.5 were used to produce valid results and findings. In the specific case of the agriculture sector, workers are found in changeable conditions and working time, therefore the effective working time distribution was estimated varying at a level of 311.6 min., 95 per cent CI (294-329.7). The observed minimal and maximal values were 179 and 500 min., respectively. The filter medium potential contamination was checked out through determination of the mass variation of the blank samples. The filter contamination was assumed possible through absorption and/or adsorption of humidity at level of minus 0.00407 mg with lower limit of minus 0.01 and upper limit of 0.00183 mg. The results on exposure indicate high exposure dose in maize crop cultivation in contrast to root plant crop cultivation. The findings show that in medium-sized farming, the average exposure to respirable dust is 0.702 (SD 0.571) and the average exposure for respirable quartz is 0.074 (SD 0.06). About 96 per cent of respirable dust exposure measurements were found in compliance with the South Africa standard for respirable dust; and for respirable quartz 74 per cent, 45 per cent and 17 per cent of exposure measurements were in compliance with the SA, NIOSH and ACGIH occupational exposure limits respectively. Each tractor operator‟s measurements showed a significant variation of the exposure concentration, probably due to the intraday and interday variation. The exposure measurements geometric standard deviation (GSD) was found equal or above 2.0 for both maize and root plant measurements and this indicates the influence of environmental factors in the exposure profile variation. CONCLUSION The research is supportive of some international published studies in which respirable quartz exposure in agriculture sector, although highly variable, has potential significance for over-exposure. The measurements of exposure to respirable quartz have shown over-exposure scenarios. However some were found below the permitted exposure limits.

Call number: LD2668 .T4 1979 B73 / Master of Science

Spatial and temporal characteristics of dust storm activity in Saudi Arabia has been established using coarse-particle (PM10) dust concentrations recorded by the KACST monitoring network during the 2000-2003 period, backward trajectory analysis and satellite imagery. Thirty three major dust episodes impacted Riyadh city during the 2000-2003 period. The majority of these intense dust episodes are experienced during the March-August period with interannual and monthly variability in both intensity and frequency. Using TOMS images in conjunction with the backward trajectories corresponding to these 33 major episodes, the dust source regions have been identified. The most vulnerable dust source areas within these identified source regions have also been determined by compiling satellite images of dusty days from the true color SeaWiFs and high resolution MODIS archives over a six-year period (2000-2005). In total 45 dust-source areas have been identified in 9 local source regions and 4 external ones. Furthermore, 38 episodes of high fine-particle (PM2.5) and PM10 dust concentrations were observed at Riyadh city and 16 and 6 episodes of elevated PM10 dust concentrations were observed at Dammam and Jeddah cities, respectively, during March-September 2006, corresponding to the dust season in Saudi Arabia. During these episodes, Riyadh city was significantly impacted by dust from the southern Iraqi source areas and the eastern source areas located to the north and to the northeast of the city, respectively. Moreover, Dammam city was also significantly impacted by dust from the southern Iraqi source areas whereas Jeddah city was evenly impacted by dust from northeastern-northwestern sources to the city, with somewhat higher PM10 concentrations from African dust source areas, located to the northwest of the city. Analysis of meteorological maps of surface pressure as well as upper air data associated with high airborne dust concentrations in Saudi Arabia was successfully performed. This analysis revealed seven common types of dust storms, triggered by a clear seasonal distribution of meteorological conditions: (1) frontal, (2) Haboob, (3) jets convergence, (4) jet streak, (5) Shamal, (6) cyclonic, and (7) gap. The majority of dust episodes that impacted Riyadh city during the study period were triggered by Haboob (~ 42 %) and Shamal (~ 37 %). Additional analyses, including elemental, ionic and biological analyses as well as model analyses were used to further characterize the airborne dust in Saudi Arabia.

Silicosis and coal worker's pneumoconiosis are serious occupational respiratory diseases associated with the coal mining industry and the inhalation of respirable dusts that contain crystalline silica. Silica exposure is an occupational health priority even when exposure has ceased or is below the occupational exposure limit (0.1 mg/m3). The objective of this study was to determine the individual contributions of the underground coal mining tasks to the total amount of respirable dust and respirable silica dust concentrations found in this environment. The tasks that were identified were continuous miner (CM) cutting, construction, the transfer point, tipping and roof bolting. Respirable dust sampling was conducted at the intake and return of each task, as well as at the intake and return of the section and the intake airway to the section. The five occupations that perform these tasks were also sampled to determine the personal exposure levels. Respirable dust concentrations and small concentrations of respirable silica dust were found in the intake airway and intake of the section, indicating that the air that enters the section is already contaminated. The respirable dust-generating hierarchy of the individual tasks was: transfer point>CM right cutting> CM left cutting> CM face cutting> construction> roof bolting > tipping. For respirable silica dust the hierarchy was: CM left cutting> construction> transfer point> CM right cutting. CM face cutting, tipping and roof bolting generated concentrations of below quantifiable levels. The personal exposures also differed and the eM and stamler operators had the highest exposure to respirable dust (3.417 ± 0.862 mg/m3) and respirable silica dust (0.179 ± 0.388 mg/m3) concentrations, respectively. Recommendations have been included for lowering the respirable dust and silica dust concentrations that are generated and that the workers are exposed to underground. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2010.

Silicosis and coal worker's pneumoconiosis are serious occupational respiratory diseases associated with the coal mining industry and the inhalation of respirable dusts that contain crystalline silica. Silica exposure is an occupational health priority even when exposure has ceased or is below the occupational exposure limit (0.1 mg/m3). The objective of this study was to determine the individual contributions of the underground coal mining tasks to the total amount of respirable dust and respirable silica dust concentrations found in this environment. The tasks that were identified were continuous miner (CM) cutting, construction, the transfer point, tipping and roof bolting. Respirable dust sampling was conducted at the intake and return of each task, as well as at the intake and return of the section and the intake airway to the section. The five occupations that perform these tasks were also sampled to determine the personal exposure levels. Respirable dust concentrations and small concentrations of respirable silica dust were found in the intake airway and intake of the section, indicating that the air that enters the section is already contaminated. The respirable dust-generating hierarchy of the individual tasks was: transfer point>CM right cutting> CM left cutting> CM face cutting> construction> roof bolting > tipping. For respirable silica dust the hierarchy was: CM left cutting> construction> transfer point> CM right cutting. CM face cutting, tipping and roof bolting generated concentrations of below quantifiable levels. The personal exposures also differed and the eM and stamler operators had the highest exposure to respirable dust (3.417 ± 0.862 mg/m3) and respirable silica dust (0.179 ± 0.388 mg/m3) concentrations, respectively. Recommendations have been included for lowering the respirable dust and silica dust concentrations that are generated and that the workers are exposed to underground. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2010.

Thesis (M.S.P.H.)--University of Michigan, 1932.

Thesis (M.S.P.H.)--University of Michigan, 1932.

Thesis (M.S.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

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