Health Impacts and Factors Related to Abnormal Symptoms from Heat Exposure among Power Plant Boiler Workers in Nonthaburi Province, Thailand

Abstract

Working in a high-temperature environment with continuous heat exposure affects the health of workers, such as uncomfortable feelings, exhaustion, fatigue, cramping, and heatstroke. Heatstroke is a hazardous condition that may result in mortality. Occupational heat-related illness statistics from 2017 show there were 103 patients which put the morbidity rate at 0.17 per 100,000 people. A preliminary survey found that a power plant in Nonthaburi Province is a combined-cycle power plant that uses natural gas as an energy source for electricity generation. The high-temperature exhaust gas (approximately 500॰C) passes and transfers heat to the boiler to produce steam which delivers to the steam turbine for generating electricity. Daily electricity generation can cause boiler carryover or high levels of chemicals in steam pipes which result in erosion, leakage, breakage of steam pipes, inadvertently ineffective electricity generation, and worker harm such as boiler explosion. To prevent damage to life and property, routine maintenance and examination are required by stopping operations and opening the cooling system for one week before operating boilers. However, the temperature in the boiler is still more than 40॰C, which results in workers in the boilers leaving before scheduled working time to rest because of lightheadedness, dizziness, and fainting. On average, six workers per week developed these symptoms. This cross-sectional study aimed to evaluate the health impact and factors related to abnormal symptoms from heat exposure among boiler workers in the power plant. All 33 workers in the maintenance and examination process of boilers in a power plant in Nonthaburi Province were enrolled. The instruments used in this study were the wet bulb globe temperature (WBGT), relative humidity meter, sphygmomanometer, infrared thermometer, fingertip pulse oximeter, and health impact and abnormal symptoms from heat exposure assessment form. Data were analyzed by using descriptive statistics, and the factors related to abnormal symptoms from heat exposure were analyzed with the Chi-square test. This study was approved by the Human Ethics Committee Research and Development Institute of Suan Dusit University (SDU-RDI 2021-031) on July 7, 2021. The results of the study showed that the wet bulb globe temperature in boilers during the working time was 32.75 – 35.24॰C. Relative humidity was 38.6-68.4% and basal metabolic rate (BMR) was 285.70 – 340.05 kcal per hour which is classified as a moderate workload. Over half of them (51.5%) had a body mass index (BMI) in the obesity range (25.0 – 29.9 kg/m²). 63.6% of workers had 20 years work experience. Heart rate after work increased by 43.0% and oxygen saturation from the fingertip decreased by 3.0%. The most common abnormal symptoms from heat exposure were excessive sweating, thirst, itchy skin, red rash, cramping, and blurred vision accounting for 96.9%, 93.9%, 69.7%, 63.6%, 48.5%, and 45.5%, respectively. The risk factors associated with abnormal symptoms from occupational risk exposure of boiler workers in power plants were weight, height, workload, duration of work, alcohol drinking, and electrolyte beverage drinking (p < 0.05). The results from this study showed that the administrator and employees who work in the power plants must control and maintain the heat in line with standards, and according to the law to ensure safety for operational workers. For example, improvement of the working environment to increase heat release, appropriate personal protective equipment (PPE) for workers, proper working hours within boilers, preparing emergency aid tools for an emergency situation, working environmental monitoring and measurement of WBGT, air velocity and relative humidity before and during working in boilers. Screening for the proper candidates to work in boilers without medical histories such as cardiovascular diseases, hypertension, metabolic disorders, and obesity. In particular, drinking alcohol before work must be prohibited to enter the boilers. The establishment should conduct a hazard assessment including surveillance of illnesses from workers exposed to heat which could prevent and reduce the risks or hazards that may occur to workers to be more effective in the future.