Volume 8, Issue 6, December Issue - 2020, Pages:859-866 |
Authors: Kumetra Achuthan, Seca Gandaseca, Balkis Fatomer A. Bakar |
Abstract: The main objective of this study was to determine the effects of heat stress on the health and productivity of forestry workers. The study included a method of assessment involving the use of standardized measuring equipment on several types of forestry works in mangrove forests. In this study, the thermal conditions and physical workload of workers were measured under various conditions, i.e., logging site, charcoal kiln, and nursery. A structure of the work-rest cycle could be designed properly using the standards of the American Conference of Governmental Industrial Hygienists (ACGIH). Result of the study showed that the mangrove forestry works in the logging site and charcoal kiln could be carried out continuously with 25% of working efficiency on achieving maximum productivity and 75% of the rest needed, while at the mangrove's nursery site it could be carried out continuously with 75% of working on achieving productivity and 25% of the rest needed. The adjustment of working productivity is therefore established between WBGT and the work-rest cycle in the design of work. Thus, it can be concluded that consideration in modifying the work-rest cycle will result in better management of heat stress rate on productivity and health being of the workers. Besides, this study recommends that more shaded areas for forestry workers to take rest to prevent heat illness and enhance working efficiency. |
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Full Text: 1 Introduction Heat stress refers to the conditions when the body can no longer dissipate body heat appropriately to the surrounding. The implication of heat stress on the workers is discomfort, increases physiological strain, decreases productivity and performance, and increases accident rates (Lucas et al., 2014). Heat stress occurs when a person’s environment (air temperature, radiant temperature, as well as humidity and air velocity), clothing, and activity combined resulting in raising the body temperature (Parsons, 1998). Also, an overexposed and prolonged working condition under a high-temperature environment contributes to the extent of heat-related illnesses. There are different severity of heat-related illnesses from mild to a serious health condition, such as heat rashes and heat cramps; or more complicated events such as heat exhaustion and heat stroke (Jagai et al., 2017), accordingly. Since heat-related complications can be prevented, due consideration should be made to promote the culture of occupational health among workers (Farough et al., 2019). Therefore, an understanding of the effects and identifying a suitable approach to reduce such impacts on the workers has been the focus of considerable researches. Labor productivity can be defined as the output rate per worker, while efficiency includes other variables, in particular the output to input ratio. The extreme climate not only causes heat stress to the worker but also results in physical workload discomfort. This discomfort directly affects the worker’s performance and productivity (Lucas et al., 2014). Most of the work construction, agriculture, and forest sectors are outdoors, in these workers directly exposed to sun, where the climate cannot be controlled. For example, the working conditions of forest workers are commonly an open area where direct sunlight is fully or partially exposed, particularly at harvesting sites. The forestry operation with the highest exposure to occupational risks and accident rates is harvesting work (FAO, 2020). In the scarcity of the data on health, climate, productivity, and other related data, it is difficult to estimate the impacts of climate change in particular, the heat stress on the health of forestry workers and their productivity. Malaysia has the sixth largest mangrove forest area with accounting for approximately 4.7% of the world's mangrove area (Satyanarayana et al., 2018). Mangrove forest plays a crucial role in the conservation of the coastal area, protecting complex marine habitats (Veettil et al., 2019), controlling nutrient cycle and storing carbon (Donato et al., 2011). Matang Mangrove Forest Reserve (MMFR) in Peninsular Malaysia has been declared as the largest mangrove forest in Malaysia and has been the longest actively and formally managed mangrove forest in the world (Goessens et al., 2014; Ariffin & NikMohd Shah, 2013). The first management plan for MMFR was established in 1902 to manage this forest to become sustainable timber and fuelwood production (Goessens et al., 2014). This plan involves clear-cutting forest patches of 30 years for the production of charcoal and intermediate thinning to obtain poles for every 15 to 20 years old forest patch (Arrifin & NikMohd Shah, 2013). Charcoal production involves harvesting the tree from the forest, moving the logs to the charcoal plant, converting the logs to charcoal, and replenishing the soil in the nursery. All these processes are typically performed manually by the workers and involve in various activities such as felling, marking and bucking, loading and unloading, wood stacking, and filling soil. Lucas et al. (2014) claim that it will be too hot to work safely outdoors and perform heavy labor for at least half of the working day (40%–60% of current working hours lost). As a result, such impacts have obvious ramifications for harvesting productivity. Moreover, climate change has been extremely severe, especially in tropical countries where the levels of heat exposure are already verging in the day time. According to Schulte & Chun (2009), there is a high relationship between global climate changes; occupational safety and health have not been substantially characterized. Current research indicates that the direct effect of climate change is increased with ambient heat exposures. It can be proven, whereby recent estimates for Thailand and Cambodia highlighted that in 2050, as the hottest month of the year. Based on the geographically located area, there is a high possibility for Malaysia to have the same phenomena shortly (Singh & Singh, 2012). To improve work performance among the forest workers, a working design has to be adjusted to suit the environmental condition of the surrounding area (2005). For instance, a work-rest cycle involves alternating between work and rest periods to limit the excessive accumulation of body heat storage. This cycle of work-rest can be refined to fit in with the work environment. A proper rest period with a conducive environment condition will imply better work performance and the health condition of the workers. However, even during recovery, the sustained heat gain beyond dissipation capacity from evaporation may persist under uncompensable heat stress (McLellan et al., 2013). A typical work/rest schedule often has a 15-minutes rest every hour of work during hot weather, but 45 minutes per hour when extreme temperature and humidity. Lack of studies and less attention to heat stress assessment and productivity among forestry workers in Malaysia motivates this study to better understand the critical heat stress to those workers. Information on the health of forestry workers focusing on heat stress, physical workload, work environment, and daily productivity is needed to provide an insight into this issue. These findings will be useful to forest management in offering a better work-rest schedule and ultimately helping to improve the productivity of the workers. The overall aim of this study is to identify the effects of heat stress on the health and productivity of forest workers using manual and semi-mechanized working methods. The specific objectives of this study are to measure the heat stress of the forest working environment; to evaluate the relationship between heat stress and the workload of forestry workers, and to determine the percentage of productivity in the working environment according to heat stress. This study will be an approach study to expand a framework to determine the effects of climate change on the occupation conditions and performances among the workers in the tropical mangrove forest. 2 Materials and Methods 2.1 Study area Mangrove Forest Reserve (MMFR) has been identified as a study area as shown in Figure 1. It is the largest Mangrove Forest in Peninsular Malaysia, particularly in Perak state, with a total acreage of 40, 466 hectares. MMFR lying between the latitude of 4°N – 5°N and the longitude 100°2’E - 45’E which is situated within the administrative district of Krian, Larut & Matang, and Manjung in Perak. The role of the forest in this area is mainly for the production of fuel-wood and pole. The production of fuelwood consists of three stages viz., harvest at the logging site, transport logs to the charcoal factory, and finally replenish the soil. Each contractor is given 2.2 ha per year and a clear-cutting method is practiced with a harvesting rotation age of 30 years. Only manual cutting is allowed by using an axe or chainsaw with a standardized cutting log length of 1.6 m. At these stages, physiological loads and productivity of the forest workers were assessed. This study site is chosen due to the manual working condition at the worksite and this area is classified as the best location for mangrove forest management. Therefore, it makes the assessment of the heat stress on the forest workers and their productivity very appropriate. 2.2 Observation of thermal conditions The Wet Globe Bulb Temperature (WGBT) is used to observe the global temperature to determine a parameter of the heat stress index. The WGBT under the exposure of direct sunlight can be calculated by using Eq. 1 (Rohles & Konz, 1987); WGBT = 0.7NWB + 0.2GT +0.1DB … Eq. 1 Where, WGBT is Wet Globe Bulb Temperature (°C); NWB is Natural Wet Bulb Temperature (°C) on exposure to natural air currents; GT as a Globe Temperature (°C) measured using a black globe thermometer and DB is Dry Bulb Temperature (°C) upon exposure to natural air currents while being protected against radiation of heat sources. 2.3 Measurement of physiological loads The forestry workers studied from three different locations of mangrove forests, i.e., logging site, charcoal kiln, and nursery. Physical workload analysis of the forestry workers was carried out using a heart rate memory device. The workers were equipped with the device to automatically measure their heart rate during working time. To calculate the energy metabolism (Eq.2), a step test was conducted for each worker to evaluate heart rate response and regression models were computed between the step test and heart rate. Using these regression models, the heart rate during the working time was converted to physical work and the energy metabolism was estimated using Eq. 2 (Hirakawa, 1983). Eg = 0.0163 x W x N x H + 1.2Bm … Eq.2 Where, Eg is the energy metabolism (kcal/min); W is the weight of a worker (kg); H is the height of step test platform (m); N is stepping rate (times/min); Bm is basal metabolism (kcal/min). Obtained data were converted from kcal to kilojoule by multiplying values in kcal by 4.2. 2.4 Work-rest Cycle and productivity The volume or units of work performed corresponding to the productive time data collected in the field were used to calculate the productivity (P) by using Eq. 3 (Giovannini, 2001). |
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