Motivation: The South-African deep level gold mining industry has adapted in many ways, as the pursuit for gold has led deep into the earth core, where rock face temperatures measure around 60°C. Ventilation adapted through engineering developments like refrigeration systems, creating cooler work environments to an extent. Despite these developments the risks of high ambient temperatures coupled with strenuous work and dehydration remains, leading to alternative methods of control that have to indicate whether employees have the necessary functional capacity to perform daily work tasks. Objectives: The objectives of this study were: to measure and compare the physiological effects of the tasks performed by workers in an underground mining environment; To measure the soundness of heart rate as a gauge of work stress in real-life work conditions, taking into account the stressors that influence it; to determine the efficacy of functional and physical work capacity assessments as a method of determining work readiness. Methods: A study group (n = 16) was chosen to represent the “most exposed” work population, all of whom have previously passed the functional work capacity and physical work capacity assessments. The assessments were repeated and the maximal oxygen uptake assessment was done. The participants were divided into two groups (n = 8) according to their work areas. Measurements were taken over a period of eight consecutive shifts. Each group was later divided into three groups as per the work they performed. Dehydration was determined through urine analysis and body weight changes. Heart rate was observed continuously through a heart rate monitor and oral temperature was measured on an hourly basis. Results: The shift durations seen during this study were much longer than the customary 8-hour work day. The mean HR results of group I, which was suspected of having the most strenuous work, were very similar to the results for group II and III. This group did, however, have the highest % heart rate ≥ 120 beats per minute and mean cumulative heart beats, group III having the lowest. All of the groups were found to be mildly dehydrated at the end of their shifts, the urine specific gravity indicating that the participants were generally already considerably dehydrated at the onset of the shifts. Group I was the only group whose mean heart rate had a statistically significant correlation (r ≥ 0.5) with % weight loss. There was a statistically significant (p ≤ 0.05) correlation between heart rate and mean oral temperature for all of the groups. The participants that passed the functional work capacity and physical work capacity assessments were found to have performed comparatively better during the real-time shifts than those that failed. Conclusions: Although there were several employees that had a high mean maximum heart rate, none of the mean heart rates were higher than the self-pacing rate of 110 beats per minute. This ability of self- pacing was seen in the way the participants were able to manage energy expenditure by alternating between heavy and lighter tasks. A great concern is the fact that all of the participants had a % weight loss (0.9 – 2.8% weight loss) indicative of mild dehydration after the shifts, on top of morning urine specific gravity samples (1.020 – 1.025) showing signs of considerable dehydration. Several correlations were found between the functional work capacity and physical work capacity assessments and maximum temperature, maximum heart rate and maximal oxygen uptake, suggesting a significant relationship between the real life situation and the homogenous laboratory setting. comparing the employees that passed the functional work capacity and physical work capacity assessment to those that failed, a marked difference was seen in their respective performances. The groups that passed had a lower mean heart rate and maximum heart rate and higher maximal oxygen uptake. It may, therefore, be concluded that the functional work capacity and physical work capacity assessments provide a valid evaluation of an individual’s work capacity and potential to cope with the varying demands of underground work. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013.

Motivation: The South-African deep level gold mining industry has adapted in many ways, as the pursuit for gold has led deep into the earth core, where rock face temperatures measure around 60°C. Ventilation adapted through engineering developments like refrigeration systems, creating cooler work environments to an extent. Despite these developments the risks of high ambient temperatures coupled with strenuous work and dehydration remains, leading to alternative methods of control that have to indicate whether employees have the necessary functional capacity to perform daily work tasks. Objectives: The objectives of this study were: to measure and compare the physiological effects of the tasks performed by workers in an underground mining environment; To measure the soundness of heart rate as a gauge of work stress in real-life work conditions, taking into account the stressors that influence it; to determine the efficacy of functional and physical work capacity assessments as a method of determining work readiness. Methods: A study group (n = 16) was chosen to represent the “most exposed” work population, all of whom have previously passed the functional work capacity and physical work capacity assessments. The assessments were repeated and the maximal oxygen uptake assessment was done. The participants were divided into two groups (n = 8) according to their work areas. Measurements were taken over a period of eight consecutive shifts. Each group was later divided into three groups as per the work they performed. Dehydration was determined through urine analysis and body weight changes. Heart rate was observed continuously through a heart rate monitor and oral temperature was measured on an hourly basis. Results: The shift durations seen during this study were much longer than the customary 8-hour work day. The mean HR results of group I, which was suspected of having the most strenuous work, were very similar to the results for group II and III. This group did, however, have the highest % heart rate ≥ 120 beats per minute and mean cumulative heart beats, group III having the lowest. All of the groups were found to be mildly dehydrated at the end of their shifts, the urine specific gravity indicating that the participants were generally already considerably dehydrated at the onset of the shifts. Group I was the only group whose mean heart rate had a statistically significant correlation (r ≥ 0.5) with % weight loss. There was a statistically significant (p ≤ 0.05) correlation between heart rate and mean oral temperature for all of the groups. The participants that passed the functional work capacity and physical work capacity assessments were found to have performed comparatively better during the real-time shifts than those that failed. Conclusions: Although there were several employees that had a high mean maximum heart rate, none of the mean heart rates were higher than the self-pacing rate of 110 beats per minute. This ability of self- pacing was seen in the way the participants were able to manage energy expenditure by alternating between heavy and lighter tasks. A great concern is the fact that all of the participants had a % weight loss (0.9 – 2.8% weight loss) indicative of mild dehydration after the shifts, on top of morning urine specific gravity samples (1.020 – 1.025) showing signs of considerable dehydration. Several correlations were found between the functional work capacity and physical work capacity assessments and maximum temperature, maximum heart rate and maximal oxygen uptake, suggesting a significant relationship between the real life situation and the homogenous laboratory setting. comparing the employees that passed the functional work capacity and physical work capacity assessment to those that failed, a marked difference was seen in their respective performances. The groups that passed had a lower mean heart rate and maximum heart rate and higher maximal oxygen uptake. It may, therefore, be concluded that the functional work capacity and physical work capacity assessments provide a valid evaluation of an individual’s work capacity and potential to cope with the varying demands of underground work. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013.

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Objectives: To determine the physiological strain on industrial workers under thermal stress on extended shifts. To continuously measure deep body core temperatures, heart rates, fluid intake, changes in hydration state and physical fatigue in order to establish acceptable levels of physiological strain. To develop a rational heat stress index compatible with these limits. To design working-in-heat protocols for a self-paced workforce. Methods: A series of studies was conducted over 77 shifts on a group of approximately 50 male volunteers working in thermally stressful environments. Continuously- recorded deep body core temperatures, heart rates, fluid consumption, urinary specific gravity and physical fatigue were measured and recorded. A new field protocol was developed to assess physical fatigue over the working shift. An original methodology was developed to allow any heat stress index to be assessed on a comparative basis with any other index. A review of the commonly used occupational heat stress indices was conducted. A new rational heat stress index was developed, based on existing biophysical relationships and recommended physiological strain limits of deep body core temperature and sweat rate. New protocols designed for self-paced work incorporating the significant risk factors for heat illness were developed and implemented in a workforce of approximately 2000 workers exposed to heat stress. The previous protocols used a shortened shift as the primary intervention to protect worker health. The subsequent protocols removed the shortened shift and replaced this with a range of other interventions. Deep body core temperature, heart rate, fluid consumption, hydration state and fatigue were measured before and after the changes in protocols. / Results: Comparisons of heat stress indices confirmed the wide divergence in guidance provided by many of the commonly-used indices in terms of acceptable working environments. It also highlighted a number of serious shortcomings in the most widely-used indices, especially WBGT and ISO7933. A new, rational heat stress index called Thermal Work Limit (TWL) was developed. This included development of a computer model incorporating key thermal physiological parameters (deep body core temperature, mean skin temperature, sweat rate, skin wettedness). There was no increase in heat stress (as indicated by average workplace environmental conditions), deep body core temperature, mean heart rate, or changes in hydration status after the changes in protocols. Average environmental conditions were severe (WBGT 30.9° C, sd 2.0° C, range 25.7-35.2° C). Environmental conditions in the study were much hotter than those considered acceptable under standards such as the ACGIH. The results showed that miners regularly exceeded those limits allowable under most current indices in terms of maximum deep body core temperature (avg 38.3° C, std dev 0.4° C), maximum temperature rise (1.4° C, 0.4° C) and maximum heat storage (431 kJ, 163 kJ), without reporting any symptoms of heat illness. A significant component of the observed elevated core temperatures was due to the normal circadian rhythm, which was measured at 0.9° C (std dev 0.2° C). Evidence was found that workers "self-pace" when under thermal stress. Fluid intake averaged 0.8 l/h during exposure (sd 0.3 l/h, range 0.3-1.5 1/h). Average urinary specific gravity at start-, mid- and end of shift was 1.0251, 1.0248 and 1.0254 respectively; the differences between start and mid-shift, mid and end-shift, and start and end-shift were not significant. / However, a majority of workers were coming to work in a moderately hypohydrated state (urinary specific gravity avg 1.024, std dev 0.0059). Involuntary dehydration was not found to occur in the study group. This is in contrast to several other studies and some of the leading heat stress standards, which are based on the premise that workers are unable to maintain their hydration status when working in the heat, even when their fluid consumption is equal to their sweat rate. Continuous heart rates measured over a shift (avg 103 bpm, 14% of shifts exceeding avg 110 bpm, 5% exceeding avg 120 bpm) were in excess of those allowable under most current indices On average, workers experienced a peak 10- minute heart rate of 140 bpm and a peak 30-minute heart rate of 130 bpm during their shifts. There was a significant increase in fatigue in the first half of the working shift (P=0.001), with workers on average showing a significant recovery in the second half of their shift (p=0.04). Conclusions: Current heat stress indices provide little common agreement as to acceptable levels of thermal strain or stress for workers, at equivalent levels of environmental stress. IS07933 is seriously flawed and the ACGIH WBGT guidelines are too conservative for acclimatised workers and are unlikely to become widely adopted by industries with well-acclimatised workers. Many of the existing indices show internal inconsistencies. / Most of the physiological heat strain limits used in existing rational heat stress indices (in terms of deep body core temperature and heart rate) are conservative for self-paced, acclimatise d, non-dehydrating male workers. Involuntary dehydration is not unavoidable when acclimatised workers are exposed to thermal stress. Heat stress standards should not limit heat exposure durations for self- paced workers who have access to water on the basis of an unavoidable body water loss. Physical fatigue does occur in workers under heat stress on extended shifts; however, most workers show a significant increase in fatigue in the first half of their shift; whereas data indicates self-paced workers undergo significant recovery in terms of fatigue in the second half of the shift. As the heat exposures in this study cover a wide range of temperatures, humidity levels, wind speeds, body morphology and VO2max, these conclusions are applicable to most thermally stressful settings involving well-informed, well-acclimatised and self-paced male workers. The major category of work type not covered by this study is that of workers in fully-encapsulated (vapour-barrier) protective clothing. In addition, this study examined acute effects of heat stress and strain, not effects that might only be manifest with chronic exposure to heat.

<p dir="ltr">Infographics are increasingly used as visual communication tools for conveying health information to diverse audiences. However, research is lacking on how specific infographic design factors influence learning outcomes. This study aimed to determine the comparative effectiveness of automatically advanced (Group A) versus manually advanced (Group B) infographics for promoting breast cancer awareness and knowledge. A mixed-methods quasi-experimental pretest-posttest design was utilized. The sample comprised 42 participants for analysis. Of these, the majority, 41 persons self-reported as female, with one participant indicating their gender as 'other.' Participant ages ranged from 25 to 55 years (M = 40.5, SD = 7.62). Most participants were well-educated, with graduate degrees or other advanced education beyond a bachelor's degree. Participants were randomly assigned to either the automatically advanced infographic group (Group A) or the manually advanced infographic group (Group B). Results indicated that Group B had significantly higher scores on the knowledge post-test compared to Group A, suggesting improved recall and comprehension of key information. There were no significant differences in cognitive load ratings or viewing duration between the groups. Qualitative feedback from participants suggested that Group B's manually advanced infographic facilitated better self-pacing and absorption of content. While the study's findings provide preliminary evidence supporting the efficacy of manually advanced infographics in learning complex health information, limitations are acknowledged. The research contributes to the design of patient education materials and underscores the necessity for further investigations across varied populations and health topics to understand the impact of infographic design more comprehensively on learning and behavior.</p>