Development of an early-warning system for site work in hot and humid environments: A case study
Introduction
Construction is a large, complex, and dynamic sector that generates employment for millions of people worldwide. However, this sector has the most fatalities and high incidence of non-fatal occupational injuries and illnesses on days away from work. Based on the estimates of International Labour Organization (ILO), at least 60,000 fatal accidents occur each year in construction sites around the world, which represent one fatal accident every 10 min [1]. In addition, the ILO estimates that the construction workers in industrialized countries are 3 to 4 times greater than other employees to die from accidents at work [2]. Aside from the dangers of being the front-liners on a jobsite, workers in the construction industry also confront potential health hazards (e.g., temperature extremes, radiation, chemicals, dusts, vibration, and noise) throughout the building process. Furthermore, about 30% of construction workers in some European countries suffer from pain and musculoskeletal disorders [3]. The occupational illnesses of construction workers have not been accurately measured, but an educated guess indicates that construction workers suffer both acute (short-term) and chronic (long-term) illnesses from their exposure to environmental hazards [4]. The health and safety of construction workers aroused greater attention from governments, industry community practitioners, and the academia.
Heat stress is a well-known occupational hazard in the construction industry [4], and climate change together with the increased frequency and intensity of extreme heat events have made risks more severe and widespread [5], [6], [7], [8]. Heat stress causes physiological and psychological discomforts, deteriorates performance and productivity, increases incident rates, and even threatens survival [9], [10], [11]. Increased thermoregulatory, cardiovascular and perceptual strains on the body promote confusion, irritability, and other emotional stress, which may cause workers to distract attention from tasks or ignore safety procedures [12]. Published reports in the United States suggest that work in construction occupation is associated with an increased risk of heat-related death and illness [13], [14]. In Japan, a total of 47 deaths due to heat stroke were reported as industrial accidents in hot environments during 2010. The construction industry is found to be more susceptible to heat stress than other industries, which is accounted for 64% of all lethal cases [15]. News reports archived in Hong Kong show alarming incidences of heat stress and verifiable reported deaths in the construction industry [16]. A recent survey revealed that 5% of construction workers had suffered from heat stroke and 23% had experienced symptoms of heat stroke [17]. In Taiwan, construction workers were identified as the most vulnerable population in which high temperature impacts on health and productivity [18]. The risk of heat stress experienced by construction workers may even be higher in the Middle East where ambient air temperatures often reach 45 °C and higher with 90% humidity [19]. Considering the high frequency of heat-related incidents in the construction industry, understanding how heat stress results in heat-related illnesses and how it affects construction workers is important in planning for intervention strategies.
To prevent heat stress, a series of fundamental practice notes and guidelines (e.g., appropriate work arrangements, shelters at work or rest places to reduce radiant heat gain, ventilation in indoor working environment, air-conditioned rest rooms, and provision of drinking water or sports drinks) have been promulgated [20], [21], [22], [23]. Likewise, the issue of working under hot weather has been a concern of academic researchers. The limits of human tolerance in terms of physiological parameters (e.g., core temperature, heart rate, skin temperature) have been evaluated at different levels of heat exposure [24], [25], [26]. Upper tolerance limits in terms of environmental indicators (e.g., temperature, humidity, wet bulb globe temperature, thermal work limit) have been explored in literature [27] and adopted by regulatory organizations [28], [29], [30]. Recently, attempts and efforts were made to establish a safety evaluation model for assessing the risk of heat stress in the workplace. Evaluating safety is not only an important means for implementing the policy but also provides a base for establishing a scientific and standardized management of enterprises [31]. For example, Ren et al. [32] established an evaluation framework for assessing the hazards of heat stress in the workplace in an underground mine. Zheng et al. [33] studied safety evaluation and early warning rating of hot and humid environment. However, no systematic and in-depth studies have been conducted with respect to safety evaluation and early warning in hot and humid environment for the identification, evaluation, control, and management of human behavioral factors. The performance of work activities befitting safety and accident prevention is a continuing and dynamic process. The key to achieving these objectives lies with workers' concentration. The cognitive condition of concentration can be viewed through the concept of mindfulness [34]. Mindful work organization and performance can be achieved through the improvement of workers' alertness to and awareness of the hazardous nature of the operations.
Occupational heat strain results from a combination of factors, which include environmental conditions, work demands, and individual characteristics. Earlier studies by Chan et al. [35], [36] established a multiple linear model (MLR) to predict a worker's heat strain to different environmental factors, work-related factors, and personal factors. However, it was challenged that heat stress and heat strain may not be linearly correlated [37]. Furthermore, the combination of the large array of personal health and lifestyle factors and their complex interaction effects is far beyond the predictive power of a MLR [38]. More advanced analytical techniques are required to tackle these complex issues. Artificial neural networks (ANNs), a form of artificial intelligence technique, is one such approach which provides a high level of flexibility and competency in nonlinearities and complex behavior. ANN provides solutions to many complex problems in biology and medicine that are beyond the computational capacity of classical mathematical and traditional statistical techniques [39]. The application of ANN in data treatment is high, particularly where systems present nonlinearities and complex behavior [40].
Innovative devices and technologies [e.g., physiological status monitor (PSM) and Ultra-Wideband (UWB)] are being used to real-time location tracking and physiological status of construction workers for enhancing construction safety and productivity [41], [42], [43], [44], [45], [46], [47]. This research aims to develop an early-warning system for construction workers against hot and humid climates using modern technologies and ANN as the principal analytical technique. The objectives of this study are to (1) develop a model to predict a worker's heat strain in hot and humid environment; and (2) identify proper precautions against the hazards and risks in hot and humid environment to prevent and reduce the harmful effects of heat exposure. Since Hong Kong is in a subtropical climate zone where air temperature typically reaches 34.5 °C on its hottest summer days [48] and business environment of the construction industry in Hong Kong is highly competitive [49], the Hong Kong construction industry is selected as a prototype for developing a more focused methodology which if successful could also be applied to other regions.
Section snippets
Heat strain assessment
Heat stress is defined by National Institute for Occupational Safety and Health as the sum of the heat generated in the body (metabolic heat) plus the heat gained from the environment minus the heat lost from the body to the environment [30]. Heat strain describes the overall physiological and psychological response resulting from heat stress [50]. International Standard Organization has identified the indicators for heat strain, including body core temperature, skin temperature, heart rate and
Material and methods
To construct the heat stress model, field studies were conducted on six construction sites during the summer time in Hong Kong (July to September in 2010 and 2011) to collect the necessary dataset.
Results
An ANN model using Levenberg–Marquart back propagation was used on the database. This model was trained using 384 randomly selected samples; the remaining 166 samples were equally divided for the ANN validation and testing process. All performance measure values confirmed a good-fit and a robust model. As shown in Fig. 7, the values obtained through the training, validation, and testing of ANN model are identical with measured data, implying the input parameters were strongly correlated with
Validation of the early-warning system
In order to validate the early warning system, a controlled experiment was conducted during the summer time in a construction site in Hong Kong. A 45 years old sheet metal worker with BMI of 23.3%, who smokes and drinks occasionally, was invited to participate. An app of the proposed system was built on iPhone platform (Fig. 8A). Prior to the test, the worker input the personal information (i.e., age, height, weight, smoking habit, and alcohol drinking habit) and job nature into the system (
Discussion
This study adopted RPE as a yardstick to evaluate the risk of heat stress that the construction workers suffered. Many reports have been published concerning RPE during exercise in the heat. RPE is regarded as an essential indicator to investigate the physical strain in hot environments. Previous studies of exercise performance in the hot environments demonstrated that the RPE is linearly correlated with heat strain indicator (e.g., body temperature, heart rate, sweating rate) [83], [84],
Conclusions
Construction workers are at a high risk of exposure to heat stress as they undertake physically demanding tasks. This study has established an algorithm to develop an early-warning system against hot and humid climates, which can alert workers to occupational heat stress and provide intervention measures as well. In this regard, the study contributes to literature by filling the research gap arising from the limited number of studies in safety evaluation in hot and humid environment. This study
Acknowledgments
This project is funded by two grants from the Research Grants Council of the Hong Kong Special Administrative Region, China (RGC Project No. PolyU510409 and PolyU510513). The support from the Hong Kong Polytechnic University's Institute of Textiles and Clothing (ITC) is deeply appreciated. The research team is also indebted to the technical support from technicians of the Hong Kong Polytechnic University and the Hong Kong Institute of Education. In particular, the participation of volunteers in
References (91)
- et al.
Excess hospital admissions during the July 1995 heat wave in Chicago
Am. J. Prev. Med.
(1999) - et al.
Determining an optimal recovery time for construction workers after working to exhaustion in a hot and humid environment
Building and Environment
(2012) - et al.
Experimental research on physiological index at the heat tolerance limits in China
Build. Environ.
(2007) - et al.
A hybrid approach for safety assessment in high-risk hydropower-construction-project work systems
Saf. Sci.
(2014) - et al.
Application of a trapezoidal fuzzy AHP method for work safety evaluation and early warning rating of hot and humid environments
Saf. Sci.
(2012) - et al.
Management of climatic heat stress risk in construction: a review of practices, methodologies, and future research
Accid. Anal. Prev.
(2014) - et al.
Location tracking and data visualization technology to advance construction ironworkers' education and training in safety and productivity
Autom. Constr.
(2013) - et al.
Integrating Augmented Reality with Building Information Modeling: Onsite construction process controlling for liquefied natural gas industry
Automation in Construction
(2014) - et al.
A BIM-based approach for automated tower crane layout planning
Automation in Construction
(2015) - et al.
Experimental study on physiological and psychological effects of heat acclimatization in extreme hot environments
Build. Environ.
(2011)
Management of climatic heat stress risk in construction: a review of practices, methodologies, and future research
Accid. Anal. Prev.
Wet-bulb globe temperature (WBGT)—its history and its limitations
J. Sci. Med. Sport
Comparing the physiological and perceptual responses of construction workers (bar benders and bar fixers) in a hot environment
Appl. Ergon.
The effectiveness of warning signs in hazardous work places: cognitive and social determinants
Appl. Ergon.
Warning signs at beaches: do they work?
Saf. Sci.
Evaluation and control of hot working environments: part I — guidelines for the practitioner
Int. J. Ind. Ergon.
GSM/EDGE: a mobile communications system determined to stay
AEU Int. J. Electron. Commun.
Comparing performances of backpropagation and genetic algorithms in the data classification
Expert Syst. Appl.
An artificial neural network model for predicting compression strength of heat treated woods and comparison with a multiple linear regression model
Constr. Build. Mater.
Status quo and open challenges in vision-based sensing and tracking of temporary resources on infrastructure construction sites
Advanced Engineering Informatics
Facts on safety at work, International Labour Office, Geneva
The health of workers in selected sectors of the urban economy: challenges and perspectives, International Labour Office, Geneva
OSH in figures: work-related musculoskeletal disorders in the EU — facts and figures
Handbook of OSHA construction safety and health
Effects of temperature on mortality in Hong Kong: a time series analysis
Heat waves in the United States: mortality risk during heat waves and effect modification by heat wave characteristics in 43 U.S. communities
Environ. Health Perspect.
The 2006 California heat wave: impacts on hospitalizations and emergency department visits
Environ. Health Perspect.
Excessive occupational heat exposure: a significant ergonomic challenge and health risk for current and future workers
Extreme Physiol. Med.
Critical review of labor productivity research in construction journals
J. Manag. Eng.
Challenges to temperature regulation when working in hot environments
Ind. Health
Occupational heat illness in Washington State, 1995–2005
Am. J. Ind. Med.
Occupation and environmental heat-associated deaths in Maricopa County, Arizona: a case-control Study
PLoS One
Prevention of heat stress disorders in the workplace
J. Jpn. Med. Assoc.
Apple Daily, construction worker died from heat stroke in a falling accident (in Chinese)
Hong Kong Daily News, 28 percent of construction workers in Hong Kong have suffered heat related illness (in Chinese)
Effects of heat on workers' health and productivity in Taiwan
Safety in the heat: a comprehensive program for prevention of heat illness among workers in Abu Dhabi, United Arab Emirates
Am. J. Public Health
Construction Industry Council, Hong Kong. Guidelines on site safety measures for working in hot weather
Publication Version 2
Department of Health, HKSAR Government, Preventive measures against heat stroke and sun burn
Health and safety executive and the health departments in England, Scotland and Wales, keep your top on health risks from working in the sun
Heat illness prevention training guide
Occupational Safety and Health Administration
Human tolerance to heat strain during exercise: influence of hydration
J. Appl. Physiol.
Heat acclimation, aerobic fitness, and hydration effects on tolerance during uncompensable heat stress
J. Appl. Physiol.
Limiting metabolic rate (thermal work limit) as an index of thermal stress
Appl. Occup. Environ. Hyg.
American conference of government industrial hygienists, thermal stress
Cited by (110)
Digital technologies in construction: A systematic mapping review of evidence for improved occupational health and safety
2023, Journal of Building EngineeringBuilding machine-learning models for reducing the severity of bicyclist road traffic injuries
2023, Transportation EngineeringQuantitative analysis of construction labor acceptance of wearable sensing devices to enhance workers' safety
2023, Results in EngineeringAn integrated approach using rough set theory, ANFIS, and Z-number in occupational risk prediction
2023, Engineering Applications of Artificial Intelligence