Project – Occupational Heat Exposure, Hydration Behaviour and Self-Reported Productivity Among Informal-Sector Workers: A Study of Selected Markets in Lagos State.

CHAPTER ONE

INTRODUCTION

Topic: Occupational Heat Exposure, Hydration Behaviour and Self-Reported Productivity Among Informal-Sector Workers: A Study of Selected Markets in Lagos State

1.1 Background to the Study

Occupational heat exposure has become an important public health and workplace safety concern, particularly in developing countries where a considerable proportion of the workforce engages in physically demanding activities under hot environmental conditions. Heat exposure occurs when workers are subjected to high environmental temperatures, direct solar radiation, humidity, inadequate ventilation and metabolic heat generated through physical activities. When the body is unable to eliminate excess heat effectively, workers may experience heat strain, dehydration, fatigue, headaches, dizziness and reduced physical capacity. The World Health Organization (WHO) and World Meteorological Organization (WMO) (2025) identify occupational heat stress as an increasing threat to workers’ health, safety and economic productivity, particularly among individuals engaged in manual labour. Similarly, Flouris et al. (2018), in their systematic review and meta-analysis, established that occupational heat strain increases workers’ vulnerability to adverse health outcomes and productivity losses. These findings demonstrate that occupational heat exposure is not merely an environmental inconvenience but an important occupational health challenge requiring attention from employers, public health authorities and policymakers.

The relationship between environmental heat and human productivity is largely influenced by the body’s physiological response to elevated temperatures. Under normal conditions, the human body maintains a relatively stable internal temperature through mechanisms such as sweating and increased blood circulation towards the skin. However, prolonged exposure to excessive heat increases the demand on these regulatory mechanisms, particularly when workers undertake strenuous activities without sufficient rest or access to cooling facilities. According to Parsons (2014), thermal conditions influence human comfort, physiological functioning and performance, while excessive heat can increase discomfort and interfere with the ability to sustain work activities. Flouris et al. (2018) further reported that workers exposed to occupational heat stress experienced an increased likelihood of heat strain, elevated core body temperature and measurable changes in hydration status. Their meta-analysis of 111 studies involving workers across different occupations and countries also identified productivity losses among workers exposed to occupational heat. Consequently, understanding the nature and intensity of occupational heat exposure is essential for evaluating the working conditions and productivity of individuals whose occupations involve prolonged exposure to hot environments.

The informal sector is particularly important in discussions of occupational heat exposure because many informal-sector workers operate in environments where formal occupational safety and health protections may be limited. Informal economic activities include petty trading, wholesale and retail marketing, loading and offloading of goods, transportation, food vending, open-air trading and other small-scale commercial activities. Unlike many formal workplaces, informal working environments may not provide adequate ventilation, temperature-control facilities, designated rest areas or organised occupational health programmes. The International Labour Organization (ILO) (2024) identifies informal-economy workers and workers in micro, small and medium-sized enterprises as important groups requiring targeted protection against excessive workplace heat. In addition, the Organisation for Economic Co-operation and Development (OECD) (2026) highlights the disproportionate productivity consequences of excessive heat among informal workers, reflecting their greater exposure and limited capacity to adapt to changing environmental conditions. These circumstances make informal-sector workers an important population for examining the combined effects of heat exposure, hydration practices and perceived work productivity.

In Nigeria, occupational heat exposure is particularly relevant because of the country’s tropical climate, high temperatures during certain periods of the year and the large number of people engaged in outdoor and poorly ventilated occupations. Workers in markets, construction sites, farms, transport terminals and other informal economic settings may spend several hours performing physically demanding tasks under direct sunlight or in environments with restricted air circulation. A Nigerian study by Sadiq et al. (2019), which examined 396 maize farmers in Gombe State, assessed environmental heat conditions alongside health and productivity indicators. The researchers recorded high wet-bulb globe temperature readings, particularly during the afternoon period, and investigated their implications for workers’ health and output. Similarly, Moda et al. (2024), in their study of Nigerian construction workers, found inadequate awareness of occupational heat-related risks and reported that 57.3% of respondents raised concerns about the unavailability of potable water at their workplaces. These studies provide evidence that occupational heat exposure and inadequate workplace adaptation are relevant concerns within the Nigerian labour environment, although the experiences of informal market workers require further investigation.

Hydration behaviour represents another important dimension of occupational health because adequate fluid intake helps the body regulate temperature and replace water lost through sweating. Workers exposed to high temperatures may lose substantial amounts of body fluid, especially when they engage in prolonged physical activities without regular drinking opportunities. Hydration behaviour refers to the practices and decisions through which individuals maintain adequate body fluid levels, including the frequency of water consumption, quantity of fluid intake, availability of drinking water, timing of hydration and willingness to take breaks for drinking. Brake and Bates (2003), in their investigation of industrial workers exposed to significant thermal stress, demonstrated the importance of adequate fluid replacement during extended working shifts. Their study showed that workers’ hydration status was influenced by fluid consumption practices and workplace arrangements. Similarly, Kenefick and Cheuvront (2012) explained that hydration plays an important role in maintaining physiological functioning during physical activity, particularly under environmental conditions that increase fluid loss. Therefore, the hydration behaviour of informal-sector workers deserves attention because access to safe drinking water, financial considerations, workload and pressure to continue working may influence how frequently they consume water during working hours.

The relationship between occupational heat exposure, hydration behaviour and productivity is particularly important because heat-related discomfort and dehydration may affect workers’ ability to maintain concentration, physical endurance and consistent work performance. Productivity in informal-sector occupations is often reflected in the volume of goods sold, number of customers attended to, quantity of goods transported, duration of effective working time and the ability to complete assigned tasks. In this study, self-reported productivity refers to workers’ personal assessment of their work output, efficiency, concentration, ability to sustain activities and perceived performance during periods of heat exposure. Flouris et al. (2018) established that approximately 30% of workers exposed to occupational heat stress reported productivity losses in the studies included in their meta-analysis. Sadiq et al. (2019) also examined the relationship between heat exposure, health outcomes and actual agricultural work output among Nigerian maize farmers. These findings suggest that excessive heat may influence work performance through physical discomfort, fatigue and reduced capacity to sustain demanding activities. However, self-reported productivity should be distinguished from objectively measured output because workers’ perceptions may also be influenced by income expectations, workload, experience and other workplace conditions.

Lagos State provides an important setting for examining these issues because of its large commercial population, concentration of markets and extensive informal economic activities. Markets in Lagos accommodate traders, food vendors, transporters, porters, artisans, cleaners and other workers who may spend considerable portions of their working days in crowded, open-air or poorly ventilated environments. The physical arrangement of market stalls, roofing materials, congestion, limited open spaces, movement of goods and availability of shaded areas may influence the level of heat experienced by workers. Furthermore, differences in occupation, working hours, age, clothing, workload and access to drinking water may produce different experiences of heat exposure and hydration behaviour among market workers. The WHO and WMO (2025) emphasise that occupational heat protection should consider the specific environmental and working conditions of different occupational groups. Similarly, the ILO (2024) recommends workplace-level measures such as hydration arrangements, rest breaks, shaded areas, heat-risk education and appropriate work schedules to reduce the effects of excessive heat. Against this background, the present study examines occupational heat exposure, hydration behaviour and self-reported productivity among informal-sector workers in selected markets in Lagos State, with particular attention to the possible relationships among these variables and the implications for workers’ health, wellbeing and economic activities.

1.2 Statement of the Problem

Occupational heat exposure is an increasing workplace health concern, yet its implications for informal-sector workers have not received sufficient attention in many developing economies. Workers in markets frequently engage in activities such as carrying heavy goods, arranging merchandise, loading and offloading products, preparing food and attending to customers in environments that may expose them to excessive temperatures. Unlike workers in some organised workplaces, market workers may have limited access to air-conditioned facilities, adequate ventilation, occupational health services and structured workplace safety programmes. Consequently, prolonged exposure to environmental heat may result in physical discomfort, excessive sweating, fatigue, dizziness and reduced capacity to sustain normal work activities. Although Flouris et al. (2018) established that occupational heat strain is associated with significant health and productivity consequences, the extent to which these challenges affect informal-sector workers in selected Lagos markets requires further investigation. The problem, therefore, is that the occupational heat conditions experienced by market workers may undermine their health and work performance without receiving adequate recognition as an occupational health issue.

Another major problem concerns the hydration behaviour of informal-sector workers exposed to elevated temperatures during working hours. Sweating is one of the body’s major mechanisms for controlling internal temperature, but excessive sweating without adequate fluid replacement may contribute to dehydration and physical exhaustion. In many market environments, workers may not have convenient access to clean drinking water or may be unable to take regular breaks because of customer demands, financial pressure and the need to maintain daily sales. Some workers may also have inadequate knowledge of the importance of regular water consumption, while others may deliberately limit fluid intake because of the inconvenience of accessing toilet facilities. Moda et al. (2024) identified inadequate potable water availability as an important concern among Nigerian construction workers, with 57.3% of respondents reporting concerns about water availability at their workplaces. Brake and Bates (2003) equally demonstrated the importance of fluid replacement in maintaining workers’ hydration status under significant thermal stress. However, it remains necessary to establish how informal-sector workers in selected Lagos markets obtain drinking water, how frequently they consume it and the factors influencing their hydration practices.

Furthermore, the possible relationship between occupational heat exposure, hydration behaviour and workers’ productivity presents another important problem. Informal-sector workers generally depend on their daily activities for income, making sustained work performance essential to their economic survival. When workers experience excessive heat, dehydration, tiredness and physical discomfort, they may find it difficult to maintain concentration, attend to customers efficiently, transport goods or sustain their normal working pace. This may result in frequent breaks, reduced working hours, slower task completion and perceived reductions in daily output. Flouris et al. (2018) found that occupational heat exposure was associated with productivity losses among a substantial proportion of workers examined in their systematic review. Similarly, Sadiq et al. (2019) investigated the effects of environmental heat on health and agricultural productivity among Nigerian maize farmers. Despite these findings, there is insufficient context-specific understanding of how market workers in Lagos perceive changes in their productivity when exposed to occupational heat and whether their hydration behaviour influences these perceptions.

The central problem addressed by this study is the limited empirical understanding of the interconnected relationship between occupational heat exposure, hydration behaviour and self-reported productivity among informal-sector workers in selected markets in Lagos State. Although existing studies have examined occupational heat stress among Nigerian farmers and construction workers, their findings cannot automatically be generalised to market workers because the nature of work, environmental conditions, access to drinking water and daily economic pressures differ across occupational settings. Moreover, much of the available evidence focuses on physical health outcomes or objectively measured productivity rather than the combined examination of workers’ heat exposure, hydration practices and self-reported work performance. This creates a need for a context-specific investigation that will establish the extent of occupational heat exposure, assess workers’ hydration behaviour, examine their perceived productivity and determine the relationship among these factors. Addressing this problem will provide useful evidence for developing practical workplace health interventions and improving the working conditions of informal-sector workers in Lagos State.

1.3 Objectives of the Study

The main objective of this study is to examine occupational heat exposure, hydration behaviour and self-reported productivity among informal-sector workers in selected markets in Lagos State.

The specific objectives are to:

1. Assess the level and patterns of occupational heat exposure among informal-sector workers in selected markets in Lagos State.

2. Examine the hydration behaviour and factors influencing water consumption among informal-sector workers in the selected markets.

3. Determine the relationship between occupational heat exposure and self-reported productivity among informal-sector workers in Lagos State.

4. Assess the influence of hydration behaviour on the relationship between occupational heat exposure and self-reported productivity among informal-sector workers in the selected markets.

1.4 Research Questions

The following research questions will guide the study:

1. What is the level and pattern of occupational heat exposure among informal-sector workers in selected markets in Lagos State?

2. What are the hydration behaviours of informal-sector workers, and what factors influence their water consumption during working hours?

3. What is the relationship between occupational heat exposure and self-reported productivity among informal-sector workers in Lagos State?

4. To what extent does hydration behaviour influence the relationship between occupational heat exposure and self-reported productivity among informal-sector workers?

1.5 Research Hypothesis

The following null hypothesis will guide the study:

H₀: There is no statistically significant relationship among occupational heat exposure, hydration behaviour and self-reported productivity among informal-sector workers in selected markets in Lagos State.

1.6 Significance of the Study

The findings of this study will be significant to informal-sector workers, market associations, public health professionals, government agencies, occupational health practitioners, researchers and policymakers.

Informal-Sector Workers: The study will provide information on the potential health and productivity implications of prolonged exposure to excessive workplace heat. It will increase awareness of the importance of adequate hydration, regular water consumption and appropriate rest practices during working hours. The findings may also encourage workers to recognise early symptoms of heat-related discomfort and adopt preventive measures that support their wellbeing and ability to sustain daily economic activities.

Market Associations and Management: The study will provide market associations and market leaders with evidence about the environmental conditions affecting workers. It may encourage the provision of accessible drinking water, shaded resting areas, improved ventilation and awareness programmes on occupational heat risks. Market associations may also use the findings to promote practical workplace arrangements that support workers’ health without unnecessarily disrupting commercial activities.

Public Health Professionals: The findings will contribute to public health understanding of environmental and occupational factors affecting informal workers. They may assist public health practitioners in designing health education programmes focusing on dehydration prevention, heat-related illnesses, workplace hygiene and environmental health protection. The study may also support community-based interventions aimed at reducing occupational health risks among vulnerable working populations.

Government and Regulatory Agencies: Government institutions and relevant occupational health authorities may benefit from the findings when developing policies and interventions for informal-sector workers. The study may provide evidence to support workplace heat-risk awareness, access to safe drinking water, environmental improvement and occupational health protection in markets. It may also encourage greater recognition of informal economic environments in occupational safety and public health planning.

Occupational Health Practitioners: The study will provide useful information for professionals involved in workplace health promotion and environmental risk management. It may help identify behavioural and environmental factors that contribute to heat-related discomfort and reduced work performance. The findings may also support the development of practical recommendations on hydration practices, rest periods and heat-risk reduction.

Researchers and Students: The study will contribute to the existing literature on occupational heat exposure, hydration behaviour and productivity, particularly within the Nigerian informal economy. It will provide a foundation for further research on occupational environmental health, climate-related workplace risks and the wellbeing of informal-sector workers. Other researchers may also use the study as a reference for investigating similar issues in other markets, states and occupational groups.

1.7 Scope of the Study

The study will focus on occupational heat exposure, hydration behaviour and self-reported productivity among informal-sector workers in selected markets in Lagos State, Nigeria.

Content Scope: The study will examine the level and patterns of occupational heat exposure, workers’ hydration behaviour, factors influencing water consumption, the relationship between heat exposure and self-reported productivity, and the influence of hydration behaviour on this relationship.

Geographical Scope: The geographical coverage will be selected markets within Lagos State. The study will concentrate on informal-sector workers operating within the selected markets rather than formal employees in organised industrial establishments.

Population Scope: The study population will comprise informal-sector workers, including traders, food vendors, market porters, loaders, transport-related workers and other eligible market-based workers who undertake their daily activities within the selected markets.

Variable Scope: Occupational heat exposure will constitute the independent variable, hydration behaviour will be examined as a behavioural and potentially modifying variable, while self-reported productivity will constitute the outcome variable.

1.8 Operational Definition of Terms

Occupational Heat Exposure: This refers to the exposure of informal-sector workers to elevated environmental temperatures, direct sunlight, humidity, poor ventilation and other workplace conditions that increase thermal discomfort during working hours.

Hydration Behaviour: This refers to the practices adopted by workers to maintain adequate body fluid levels, including the frequency and quantity of water consumption, availability of drinking water and regular fluid intake during work.

Self-Reported Productivity: This refers to workers’ personal assessment of their work performance, efficiency, concentration, ability to sustain physical activities and perceived output during working hours.

Informal-Sector Workers: These are individuals engaged in economic activities outside fully formalised employment arrangements, including petty trading, food vending, loading and offloading, transportation and other small-scale market activities.

Heat Stress: This refers to the overall environmental and physical conditions that place excessive thermal demands on the body and may interfere with its ability to maintain normal internal temperature.

Heat Strain: This refers to the physiological responses experienced by the body when exposed to heat stress, including increased sweating, elevated heart rate, fatigue and increased body temperature.

Dehydration: This refers to a condition in which the body loses more water than it takes in, resulting in insufficient body fluid for normal physiological functioning.

Selected Markets: These refer to the specific markets within Lagos State that will be chosen as the geographical locations for conducting the study.

Work Productivity: This refers to the ability of workers to perform their occupational activities efficiently and consistently within their normal working periods.

Project – Occupational Heat Exposure, Hydration Behaviour and Self-Reported Productivity Among Informal-Sector Workers: A Study of Selected Markets in Lagos State.