A research project submitted in partial fulfillment of the requirements for the degree of MA by coursework and Research Report in the field of Organisational Psychology in the Faculty of Humanities. University of the Witwatersrand, Johannesburg, November 2017 / The current study utilized the Attention Restoration Theory to investigate whether plants in an office context produced restorative effects that enable employees to perform better. The Attention Restoration Theory asserts that individuals will experience increased concentration after spending time in or viewing nature. This study was one of the first attempts to empirically investigate the effect of indoor plants on experiences of performance outcomes and perceptions of Indoor Environmental Quality (IEQ) within South Africa. The researcher aimed to assess whether the individual’s nature identity moderated the impact of the plants. Most previous studies on the outcomes of indoor plants have been conducted in Western, Northern hemisphere contexts. In this experimental study, 120 participants were randomly assigned to one of three conditions: (1) no plants or pictures of plants; (2) only plants; (3) only canvas pictures of plants. The rooms were identical in every other respect. Participants completed two tasks (a card-sorting task and a reading task) and two questionnaires, namely the connectedness to nature scale to assess participant’s nature identity and a previously developed questionnaire that aimed to assess task performance. Additionally, SE controls IEQ monitors were positioned in each office to measure fluctuations of air quality (i.e. temperature, humidity and carbon dioxide levels) in order to assess IEQ. The results from a series of ANOVA’s demonstrated a reduction in participants’ errors (F (2, 117) = 7.137, p = 0.001), a positive reaction to the given task (F (2, 117) = 8.904, p = 0.000), as well as a reduction in participants’ task completion time (F (2, 117) = 43.422, p = 0.000) in the plants condition. These results demonstrated a statistically significant effect on performance in the presence of plants as well as an improvement in air quality through a reduction of carbon dioxide (F (2, 117) = 6.429, p = 0.000). The results revealed that the plants condition was statistically significantly different from that of the pictures of plants and the control condition with regards to the performance outcomes. The result from the two-way ANOVA’s demonstrated that nature identity did not moderate the above relationships (Errors: F (1, 114) = 2.060, p = 0.132; Completion time: F (1, 114) = 0.967, p = 0.383; Reaction to the task: F (1, 114) = 0.017, p = 0.983). This study enhances knowledge regarding indoor plants within the South African context as well as practically influencing working environments where employees are expected to be productive. / MT 2019

Arborists are exposed to many occupational hazards and experience more than three times the overall fatality rate of all U.S. workers. Investigations into fatal incidents lead to a better understanding of industry dangers. However, this knowledge does not extend to how tree workers operate when an injury or fatality does not occur. Current research regarding fatal and nonfatal injuries does not include the accreditation status of the company at which the worker was employed, nor whether certified arborists were on staff. Given the highly skilled nature of the work involved, certification and accreditation might ensure a minimum level of demonstrated safety practices. This study aimed to 1. Determine whether certification and accreditation in the tree care industry are associated with safer workplace behavior, and 2. Identify safety practices that tree workers commonly violate. Tree care companies in southern New England were divided into three categories: accredited, non-accredited with certified arborists on staff, and non-accredited with no certified arborists on staff. A stratified random sample of 63 companies was evaluated in the field by direct observation, assessing workers’ adherence to the industry’s safety standard, the American National Standards for Arboricultural Operations (ANSI Z133.1-2006). Analysis indicated that, overall, accredited companies and those with certified arborists on staff complied with the Z133.1 Standard more than those without. Although these companies were more compliant, few significant differences emerged, and low overall compliance was found for personal protective equipment and chainsaw and chipper safety. There were low levels of compliance across all types of companies with the basic aspects of safety, including feeding the chipper from the curbside, not drop-starting a chainsaw, and using head, eye, and hearing protection. Implications of findings include possible considerations for improvements on accreditation and certification processes. Further findings address aspects of the Z133.1 Safety Standard that are currently unclear.

The rate of heat-related fatalities in crop production workers is almost 20 times that of other industries. Heat stress was investigated in migrant tomato workers in July, 2012, using measurements of body temperature, heart rates, body weight loss, evaluation of the thermal environment, and survey data. Using occupational safety criteria, these workers were found to work in an environment that should require protective measures to prevent heat strain. Increases in body temperature, heart rate, and physiological strain correlated with heat exposure. One third of workers had body weight percentage losses that indicated dehydration. However, working in hot environments appears to elicit a low magnitude of strain in well acclimated workers who self-pace. Key findings suggest the need for worker and employer safety training regarding acclimation and hydration. Survey data showed that less than 30% have had any heat-related safety training.

Introduction: A task-associated analysis of ammonia and particulate matter concentrations was conducted on swine farms in breeding and gestation barns. The purpose of this study was to determine if specific tasks performed by workers increase concentrations of ammonia and particulate matter exposure. Methods: An exploratory, descriptive design was used to determine if swine confinement workers have increased ammonia and particulate matter exposure when performing assigned tasks in breeding and gestation barns. A convenience sample of 8 workers volunteered from among all breeding and gestation workers (n=24). Data collection occurred in the morning at each of the 8 farms and continued until tasks were completed (~4 hrs). Analysis of covariance (ANCOVA) was computed to determine if the type of task or type of barn was related to workers' exposure to ammonia or particulate matter. Results: Ammonia levels were below the sensitivity of the instrument (<0.1) except on 1 morning when the ammonia concentration was recorded at 8 ppm. However, concentrations above 0.1 ppm lasted for less than 5 minutes. Consequently, this variable was not included in the analysis. Correlation analysis was used to answer the 1st research question. The results suggested a statistically significant decrease in particulate matter as the number of operating fans increased. Analysis of covariance (ANCOVA) was used to answer the last 2 research questions. The results suggested a significant interactive effect between the type of confinement barn and the type of tasks workers were performing. The barn types differed by the number of exhaust fans and the type of animal waste disposal system. Conclusions: Occupational health nurses can use study results to implement interventions to minimize worker exposures. These results indicate that understanding the relationship between building design and type of work tasks along with the importance of proper ventilation may minimize worker exposure to harmful particulate matter in SCBs during the summer months.

The genetic variation among extant life forms reflects the outcomes of evolution. The fodder of evolution – germline mutations – is shaped by the interplay among evolutionary forces – notably natural selection and random genetic drift. In turn, these forces leave footprints recorded in the genetic variation of extant life forms. Characterizing these footprints to understand how evolution works is at the heart of population genetics. To this end, massive datasets of genetic variation have opened new avenues of research, around how mutation rates evolve for instance, and reinvigorated long standing questions in population genetics, notably about the genetic basis of adaptation. In turn, theoretical models of evolution inform what kind of footprints we expect evolution to leave behind in such data. Two theoretical models that investigate open questions in population genetics are described in this thesis. In Chapter 1, I consider the evolution of germline mutation rates, particularly on short evolutionary timescales, and ask if recently observed variation in mutation rates among human lineages could be explained by evolution at genetic modifiers of mutation rates. Genetic modifiers of mutation rates are expected to evolve under purifying selection: mutations at modifiers that increase mutation rates (“mutator alleles”) should be selected against, because they increase the burden of deleterious mutations in individuals who carry them. The frequencies of mutator alleles are also affected by mutation, genetic drift, and demographic processes. We model the evolution of mutator alleles under the interplay of these forces and characterize the dynamics at mutation rate modifiers as a function of the efficacy of selection acting on them. We find that modifiers under intermediate selection have the greatest contribution to variation in mutation rates between distantly related populations, but only variation at strongly selected modifiers turns over fast enough to explain variation in mutation rates among human lineages. We also predict that strongly selected modifiers could be potentially identified in the contemporary datasets of human pedigrees used to study germline mutations. In Chapter 2, I consider a central and enduring question in evolutionary biology: whether adaptation typically arises from few large effect changes or from many small effect changes. Both sides are supported by ample evidence. Yet it is unclear how to translate this evidence into general answers about the genetic basis of adaptation, in part because different methodologies have different limitations and ask different questions. Theory may offer a way out of this quagmire or at least a start. To this end, we reframe the question in terms of traits and ask: how does the genetic basis of adaptation depend on the ecological and genetic attributes of a trait? To start answering this question, I model adaptation in a simple yet highly relevant setting. I consider a trait under stabilizing selection and assume the distribution of trait values in the population is initially at mutation-selection-drift-balance. I then characterize the adaptive response that is elicited by a sudden change in the environment. I find that the adaptive response, and notably the probability that adaptation arises from the fixation of large effect alleles, depends on the size of the environmental change and the genetic architecture of the trait. These attributes are measurable and can be directly related to the disparate evidence that we have about the genetic basis of adaptation. Thus, this kind of modeling may help translate such evidence into general conclusions about how traits evolve. My thesis work was interrupted by the global COVID-19 pandemic, and in response to this pandemic, governments around the world implemented shelter-in-place protocols. However, essential workers were exempt from these protocols, potentially decreasing their efficacy. In Chapter 3, we describe our epidemiological project, aimed at understanding the impact of essential workers on epidemic control. To this end, we model three different archetypes of essential workers under a reasonably realistic SEIR model of the COVID-19 pandemic. We find that the different social interactions that essential workers maintain qualitatively changes their personal risk of infection and the spread of the overall epidemic. These results highlight the utility of not considering essential workers as a monolithic group but instead distinguishing between the impact of different types of essential workers on epidemic control.

On December 29, 1970, the President signed into law the Williams-Steiger Occupational Safety and Health Act (OSHA) of 1970, which became effective April 28, 1971. The purpose of this act is to assure safe and healthful working conditions for the nation's wage earners. The law provides that each employer has the basic duty to furnish his employees a place of employment which is safe from recognized hazards that cause death or serious physical harm. The implementation of the OSHA Act has been the most extensive intervention into the day-to-day operation of American Industry in history. Originally, employers expressed doubt that they could meet requirements of the OSHA standards and remain in business. This investigation reveals that a concentrated effort to organize a safety group trained in OSHA standards and a program for identifying costs for correction can lead to an economical compliance program which is advantageous to the employer and employee as well. Three aerospace firms were investigated for the impact of OSHA. Results show that approximately $400,000 will bring each of these firms into compliance. Compliance cost, however, is greatly determined by the type of industry, age of facility, and the safety program in effect at the facility.

Employee injury rates in U.S. land-based operations in the energy industry are 2 to 3 times higher relative to other regions in the world. Although a rich literature exists on drivers of safety performance, no previous studies investigated factors influencing this elevated rate. Leadership has been identified as a key contributor to safety outcomes and this grounded theory study drew upon the full range leadership model, situational leadership, and leader-member exchange theories for the conceptual framework. Leadership aspects influencing safety performance were investigated through guided interviews of 27 study participants; data analyses included open and axial coding, and constant comparisons identified higher-level categories. Selective coding integrated categories into the theoretical framework that developed the idealized, transformational leader traits motivating safe behaviors of leading by example, expressing care and concern for employees' well-being, celebrating successes, and communicating the importance of safety (other elements included visibility and commitment). Employee and supervisor participants reported similar views on the idealized leader traits, but low levels of these qualities may be driving elevated injury rates. Identifying these key elements provides the foundation to creating strategies and action plans enabling energy sector companies to prevent employee injuries and fatalities in an industry where tens of thousands of employees are subjected to significant hazards and elevated risks. Creating safer workplaces for U.S. employees by enhancing leaders' skills, building knowledge, and improving behaviors will improve the employees' and their families' lives by reducing the pain and suffering resulting from injuries and fatalities.

The existence of an occupational health and safety policy is believed to be evidence of management accepting their occupational health and safety role in terms of the Occupational Health and Safety Act. It is accepted that this results in management ensuring the provision of a safe workplace. Despite the emphasis in legislation (the Occupational Health and Safety Act) on the need for management to implement comprehensive occupational health and safety policies, there is a lack of research on the implementation and efficacy of occupational health and safety policies in the workplace. This study investigates the efficacy with which management carries out their occupational health and safety duties and responsibilities when implementing the provisions of an occupational health and safety policy in the workplace. A number of factors are essential to the efficient performance of management in this regard. These factors include managerial commitment, practices and strategies; communication practices and structures; training initiatives and information; the extent of employee and trade union involvement; and the infrastructure of the organisation. This research study is primarily qualitative in nature. Semi-structured interviews were the primary tool used by the researcher to collect the data. The case-study research method was employed to assist the researcher in collecting the data. The participants involved in the research were selected using the principles of strategic informant sampling and expert choice sampling. The participants consisted of a sample of management, employees and shop stewards. The research findings indicate that firstly, the presence of occupational health and safety policies, practices, strategies and systems in the workplace do not automatically result in reduced hazards, accidents or deaths in the workplace. Secondly, the participation schemes and the communication practices put in place by management are weak. The reason for their weakness is their ineffective implementation by management and use by employees and the trade union. Thirdly, management has a definite impact on the involvement, attitudes and actions of the employees and the trade union in occupational health and safety issues. Fourthly, there is an unequal partnership between management and employees as a result of the educational differences regarding occupational health and safety between them. The outcome is that management and employees are faced with numerous challenges in relation to occupational health and safety. Contributing to this challenge is a lack of sufficient resources allocated to training, resulting ultimately in the ineffective monitoring of occupational health and safety in the workplace. The existence of occupational health and safety structures and systems does not provide the essential evidence to suggest that their mere presence makes a difference to the workplace safety level. However, through more co-operation and participation by all the parties, these structures and systems have the potential to be effective. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Heat stress is a recognized occupational hazard present in many work environments. Its effects increase with increasing environmental heat loads. There is good evidence that exertional heat illness is associated with ambient thermal conditions in outdoor environments. Further, there is reason to believe that risk of acute injury may also increase with the ambient environment. For these reasons, the assessment of heat stress, which can be done through the characterization of the wet bulb globe temperature (WBGT), is designed to limit exposures to those that could be sustained for an 8-h day. The ACGIH Threshold Limit Value (TLV) for heat stress was based on limited data from Lind in the 1960s. Because there are practical limitations of using thermal indices, measurement of physiological parameters, such as body temperature and heart rate are used with environmental indices or as their alternative. The illness and injury records from the Deepwater Horizon cleanup effort provided an opportunity to examine the effects of ambient thermal conditions on exertional heat illness and acute injury, and also the cumulative effect of the previous day’s environmental conditions. The ability of the current WBGT-based occupational exposure limits to discriminate unsustainable heat exposures, and the proposal of alternative occupational limits was performed on data from two progressive heat stress protocol trials performed at USF. The USF studies also provided the opportunity to explore physiological strain indicators (rectal temperature, heart rate, skin temperature and the Physiological Strain Index) to determine the threshold between unsustainable and sustainable heat exposures. Analysis were performed using Poisson models, conditional logistic regressions, logistic regressions, and receiver operator curves (ROC curves). It was found that the odds to present an acute event, either exertional heat illness or acute injuries increased significantly with rising environmental conditions above 20 °C (RR 1.40 and RR 1.06, respectively). There was evidence of the cumulative effect from the prior day’s temperature and increased risk of exertional heat illness (RRs from 1.0–10.4). Regarding the accuracy of the current TLV, the results of the present investigation showed that this occupational exposure limit is extremely sensitive to predict cases associated with unsustainable heat exposures, its area under the curve (AUC) was 0.85; however its specificity was very low (specificity=0.05), with a huge percentage of false positives (95%). The suggested alternative models improved the specificity of the occupational exposure limits (specificities from 0.36 to 0.50), maintaining large AUCs (between 0.84 and 0.89). Nevertheless, any decision in trading sensitivity for specificity must be taken with extreme caution because of the steeped increment risk of heat related illness associated with small increments in environmental heat found also in the present study. Physiologic heat strain indices were found as accurate predictors for unsustainable heat stress exposures (AUCs from 0.74 to 0.89), especially when measurements of heart rate and skin temperature are combined (AUC=0.89 with a specificity of 0.56 at a sensitivity=0.95). Their implementation in industrial settings seems to be practical to prevent unsustainable heat stress conditions.