METHOD: A cross-sectional study was performed in March and April 2016. The outdoor temperatures were measured using the wet-bulb globe temperature (WBGT) tool. The participants completed a self-administered questionnaire containing sociodemographic factors prior to work shift; while working profile, hydration practices, and HRI symptoms at the end of work shift. The hydration status of the respondents was assessed by direct observation of their urine colour. Multiple logistic regression was performed to ascertain the effects of age, working profile, hydration practice, history of previous HRI, and hydration status on the likelihood that outdoor workers having moderate to severe HRI.
RESULTS: A total of 320 respondents completed the questionnaire. The mean (standard deviation) outdoor workplace temperature was 30.5°C (SD 0.53°C). The percentage of respondents who experienced moderate to severe HRI was 44.1%. The likelihood that outdoor workers experienced moderate to severe HRI symptoms was associated with irregular fluid intake [odds ratio (OR): 16.11, 95% confidence interval (95%CI): 4.11; 63.20]; consumption of non-plain water (OR: 5.92, 95%CI: 2.79; 12.56); dehydration (OR: 3.32, 95%CI: 1.92; 5.74); and increasing outdoor workplace temperature (OR: 1.85, 95%CI: 1.09; 3.11).
CONCLUSION: Irregular drinking pattern and non-plain fluid intake was found to have a large effect on HRI severity among outdoor workers exposed high temperatures during a heat wave phenomenon.
MATERIALS AND METHODS: This cross-sectional study was conducted in a PO mill located in Mukah, Sarawak, Malaysia. Thirty-one workers from the four workstations (sterilizer, boiler, oil, and engine rooms) were selected as the respondents in this study. Wet Bulb Globe Thermometer was used in this study to measure the environmental temperature (WBGTin). Body core temperature (BCT), blood pressure (BP), and heart rate (HR) were recorded both before and after working in order to assess the physiological effects of heat stress on workers. A set of questionnaires were used to determine sociodemographic characteristics of the respondents and their symptoms related to heat stress. Data were then analyzed using SPSS Ver28.
RESULTS: The WBGTin was found to be above the ACGIH threshold limit value of heat stress exposure in the engine room, sterilizer, and boiler workstations (>28.0°C). Additionally, there was a significant difference in the worker's BCT in these three workstations before and after work (p<0.05). Only the systolic BP and HR of those working at the boiler workstation showed significant difference between before and after work (p<0.05). The most typical symptoms that workers experience as a result of being exposed to heat at work include headache and fatigue. However, statistical analysis using Spearman Rho's test showed that there is no correlation between heat stress level with physiological changes and health-related symptoms among study respondents (p>0.05).
CONCLUSION: Results of the present study confirmed that workers in PO mill were exposed to high temperatures while at work. Although the evidence indicates the physiological parameters in general are not significantly affected while working, it also demonstrated that worker's body adapts and acclimates to the level of heat. Even so, precautions should still be taken to reduce future heat exposure. It is recommended that a physiological study be carried out that focuses on cognitive function impairment to support the evidence regarding the effects of heat stress on PO mill workers.
METHODS: In this longitudinal study, we randomly selected community members aged between 18 and 70 years who resided in Segamat district of Johor state, Malaysia. Over 21 days, we conducted three home visits to each participant. During each visit, participants completed a questionnaire consisting of Likert scale, multiple choice, and free text questions and we collected quantitative and qualitative data. These inquiries assessed the participants' perception of heat as health threat, whether or not they took heat preventive measures, and the specific protective measures they routinely employed. Descriptive data analyses were conducted and patterns of protective measures were investigated.
FINDINGS: Between March 29 and July 31, 2023, 120 participants (72 women and 48 men) completed 360 questionnaires over three home visits. Initially, 58% participants recognised heat hazards to daily activities, decreasing to 42% and 35% by visits 2 and 3. Participants took preventive measures throughout the day, which was consistently high between 1200 h and 1400 h, with 77% of participants taking preventive measures on visit 1, 82% on visit 2, and 82% on visit 3. Use of preventive measures was also high between 1400 h and 1730 h, with 77% using preventive measure on visit 1, 81% on visit 2, and 79% on visit 3. The most common protective measures were fans (used by 68-88% of participants), drinking more water (70-78% of participants), and resting (44-72% of participants). The least common were relocating to cooler places, removing clothes, and using wet towels (0-2·5%). Despite high temperatures, perceptions of heat risks decreased over time. Participants took basic protections, especially at midday, but improved literacy and affordable cooling options are needed to protect vulnerable rural populations.
INTERPRETATION: Our findings underline the need to improve heat literacy and adaptation as only half of the population assessed perceived heat as a potential health hazard and practised limited heat protective measures. Addressing climate change and health necessitates fundamental behavioural changes on the part of individuals and communities, to protect them against the adverse effects of heat.
FUNDING: Monash University Malaysia and Heidelberg Institute of Global Health, Heidelberg University.