Project – Noise Pollution and Sleep Disturbance among Residents Living around Major Transport Corridors: A Study of Selected Communities in Lagos Mainland

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Noise pollution has increasingly become an important environmental and public health concern, particularly in rapidly urbanising cities where residential, commercial, industrial, and transportation activities occur within close proximity. Unlike many forms of environmental pollution that are visible, noise pollution is often less obvious, yet persistent exposure can affect physical health, psychological wellbeing, communication, concentration, and sleep. Environmental noise may originate from road traffic, railways, aircraft, industries, generators, construction activities, commercial activities, religious activities, and other urban sources. The World Health Organization (WHO, 2018) recognises environmental noise as an important public health issue and provides evidence-based recommendations for reducing exposure to transportation noise because of its adverse effects on human health and wellbeing. In particular, road traffic noise is identified as an important environmental exposure requiring population-level interventions, especially in densely populated urban communities where residents may have limited opportunity to escape persistent noise.

Sleep is an essential physiological process required for physical restoration, psychological functioning, cognitive performance, emotional regulation, and general health. Adequate and uninterrupted sleep allows the body and brain to recover from daily activities, whereas repeated interruptions may result in daytime sleepiness, fatigue, poor concentration, irritability, impaired productivity, and other health consequences. Environmental noise can interfere with sleep through physiological arousal, changes in sleep stages, awakenings, difficulty initiating sleep, and difficulty returning to sleep after awakening. Basner and McGuire (2018), in the systematic review conducted for the WHO Environmental Noise Guidelines, found that transportation noise was associated with objectively measured changes in sleep physiology and subjectively reported sleep disturbance. Their meta-analysis showed that increasing nighttime exposure to road, rail, and aircraft noise was associated with greater odds of severe sleep disturbance. The evidence therefore establishes sleep as one of the important pathways through which environmental noise can affect population health.

Road traffic is particularly important in relation to environmental noise because traffic noise is continuous, widespread, and difficult for residents living close to busy roads to avoid. Motor vehicles generate noise through engines, exhaust systems, tyres, horns, braking, acceleration, and interaction with road surfaces, while congestion can prolong exposure by producing a continuous stream of vehicles over extended periods. Lagos, as a densely populated and highly motorised metropolitan environment, experiences substantial transportation activity. A study of commuter exposure in Lagos reported considerable noise exposure during journeys through the metropolis, with the highest mean noise exposure reaching approximately 85 dB(A) among microbus trips with open windows and a 99th-percentile level of about 92 dB(A). The researchers noted that the high exposure was associated with the characteristics of urban transportation and suggested that improved mass transportation could reduce exposure (Kinney et al., 2017). These findings demonstrate that transportation represents a significant source of environmental noise within Lagos and provide a basis for examining the implications for people who live permanently alongside major transport corridors.

The relationship between road traffic noise and sleep disturbance has also been demonstrated through epidemiological and experimental research. Basner et al. (2018) reported that a 10-dB increase in nighttime road traffic noise was associated with increased odds of being highly sleep disturbed, while nighttime traffic noise was also associated with an increased probability of awakening during sleep. Similarly, an updated systematic review and meta-analysis by Smith et al. (2022), which incorporated studies published after the original WHO review, found a significant association between increasing nighttime road traffic noise and self-reported sleep disturbance. The authors reported that for questions specifically identifying noise as the cause of disturbance, the odds of being highly sleep disturbed increased significantly with each 10-dB increase in nighttime road traffic noise. These findings are important because residents living around busy transport corridors may experience repeated vehicle-related noise events throughout the night, thereby interfering with the continuity and restorative quality of their sleep.

The Nigerian context provides additional evidence that road traffic noise can produce substantial sleep-related problems among people living near busy roads. Obisung, Onuu, Menkiti, and Akpan (2016) investigated road traffic noise-induced sleep disturbances in five cities in Eastern Nigeria, namely Calabar, Uyo, Umuahia, Owerri, and Port Harcourt. Their study combined acoustic measurements with questionnaire responses and compared high- and low-noise areas. The researchers reported very high levels of reported sleep disturbance among residents exposed to high road traffic noise, with nighttime disturbance ranging from approximately 98.5% to 98.8% across the cities studied. The study demonstrated that residents living along busy roads were particularly vulnerable to sleep disruption and concluded that excessive road traffic noise represented a serious environmental health concern. Although the study was conducted in Eastern Nigeria rather than Lagos, its findings demonstrate the relevance of traffic noise as a sleep-related environmental problem within Nigerian urban communities.

Evidence specifically from Lagos State further highlights the seriousness of environmental noise exposure among residents. Akinnubi (2020), in an assessment of noise pollution and perceived health challenges among residents of Lagos State, found that heavy traffic was one of the major sources of environmental noise, alongside religious activities, industrial activities, and power-generating plants. The study identified insomnia or sleep disturbance among the perceived health challenges associated with environmental noise exposure, together with hypertension, nervousness, headaches, loss of hearing, and poor concentration. More recent research by Iyendo, Adewole, and Ganiyu (2024) similarly examined urban noise pollution and public health in Lagos and reported a significant positive relationship between perceived noise pollution and reported health problems, including sleep disturbances. These studies indicate that noise pollution is already recognised as a health concern among Lagos residents; however, the specific experience of residents who live immediately around major transport corridors requires further investigation because traffic-related noise may be persistent and may differ according to road characteristics, traffic volume, vehicle types, and time of day.

The problem is particularly relevant to Lagos Mainland because major transport corridors frequently pass through or alongside densely populated residential communities, creating situations in which residents may be exposed to traffic noise within and around their homes. Lagos State Environmental Protection Agency (LASEPA) provides noise-control standards that specify that noise levels in residential areas should not exceed 55 decibels during the day and 45 decibels at night, reflecting the importance of protecting residents from excessive environmental noise during periods of rest. The WHO similarly recommends reducing average road traffic noise and specifically recommends reducing nighttime road traffic exposure below 45 dB Lnight because exposure above this level is associated with adverse effects on sleep (WHO, 2018). Despite these standards, evidence of substantial noise exposure and sleep-related complaints among Lagos residents suggests that the existence of regulations does not necessarily mean that residential communities are adequately protected. Therefore, examining noise pollution and sleep disturbance among residents living around major transport corridors in selected Lagos Mainland communities is important for generating local evidence that can support environmental health interventions, urban planning, traffic-noise management, and stronger enforcement of noise-control measures.

1.2 Statement of the Problem

Noise pollution has become an increasingly important environmental health challenge in urban communities, particularly in cities where transportation, commercial activities, residential settlements, and other land uses exist in close proximity. Lagos represents a major urban centre in Nigeria with intense transportation activity and densely populated communities. Residents who live close to major transport corridors may be exposed to continuous traffic noise from vehicle engines, horns, braking, acceleration, motorcycles, buses, trucks, and other transport-related activities. While traffic corridors are essential for urban mobility and economic activity, persistent exposure to transportation noise may impose health burdens on people living within affected communities. Evidence from Lagos has already identified heavy traffic as one of the major sources of environmental noise and has associated noise exposure with several perceived health problems, including sleep disturbance (Akinnubi, 2020).

A major concern arising from persistent transportation noise is its potential effect on normal sleep. Residents living close to busy roads may experience difficulty falling asleep, repeated awakening during the night, difficulty returning to sleep, early morning awakening, shortened sleep duration, poor perceived sleep quality, and tiredness during the day. International evidence has consistently demonstrated an association between nighttime transportation noise and sleep disturbance. Basner and McGuire (2018) found significant relationships between road traffic noise and both subjective sleep disturbance and objective sleep-related outcomes, while Smith et al. (2022) confirmed the association in an updated systematic review and meta-analysis. Nigerian evidence also demonstrates the seriousness of the problem: Obisung et al. (2016) found very high levels of reported sleep disturbance among residents living in high road traffic noise areas in several Eastern Nigerian cities.

Despite these findings, there remains a need for more location-specific evidence concerning residents living around major transport corridors in Lagos Mainland. Existing Lagos studies have generally considered environmental noise from multiple sources, including traffic, religious activities, generators, industrial activities, and other urban sources, rather than isolating the experience of residents whose homes are situated around major transportation routes. This distinction is important because transportation noise differs from intermittent community noise in its frequency, duration, timing, and predictability. Residents living close to major transport corridors may experience noise from early morning through late night, while commercial transportation and other road activities can extend exposure into periods normally reserved for sleep. Akinnubi (2020) specifically identified heavy traffic as a major noise source in Lagos and reported sleep disturbance among perceived health challenges, indicating the need for more focused investigation of traffic-related exposure in residential communities.

The problem is further complicated by the gap between environmental noise-control standards and the lived experiences of residents. LASEPA has established residential noise limits of 55 dB during the day and 45 dB at night, while WHO recommendations similarly emphasise lower nighttime road traffic noise exposure to protect sleep. Nevertheless, evidence from Lagos indicates that urban noise exposure remains substantial, and recent research has reported elevated noise levels and adverse health outcomes among Lagos residents. The specific extent to which residents living around major transport corridors in selected Lagos Mainland communities experience sleep disturbance, the forms of sleep disturbance they experience, and the relationship between perceived traffic noise exposure and sleep disturbance therefore requires empirical investigation. This study consequently seeks to examine the relationship between noise pollution and sleep disturbance among residents living around major transport corridors in selected communities in Lagos Mainland, thereby providing evidence that can assist environmental health authorities, urban planners, local government authorities, transport managers, and community stakeholders in developing appropriate noise-control and public-health interventions.

1.3 Purpose of the Study

The main purpose of this study is to examine the relationship between noise pollution and sleep disturbance among residents living around major transport corridors in selected communities in Lagos Mainland.

Specifically, the study seeks to:

1. determine the major sources of noise pollution experienced by residents living around major transport corridors in selected Lagos Mainland communities;
2. assess the perceived level of noise pollution among residents living around major transport corridors;
3. determine the prevalence and forms of sleep disturbance experienced by residents;
4. examine the frequency with which residents experience difficulty falling asleep, nighttime awakening, difficulty returning to sleep, and daytime tiredness.

1.4 Research Questions

The following research questions will guide the study:

1. What are the major sources of noise pollution experienced by residents living around major transport corridors in selected Lagos Mainland communities?
2. What is the perceived level of noise pollution among residents living around major transport corridors?
3. What forms of sleep disturbance are experienced by residents living around major transport corridors?
4. How frequently do residents experience difficulty falling asleep, nighttime awakening, difficulty returning to sleep, and daytime tiredness?

1.5 Research Hypothesis

The following null hypothesis will be tested at the 0.05 level of significance:

H₀: There is no significant relationship between noise pollution and sleep disturbance among residents living around major transport corridors in selected communities in Lagos Mainland.

1.6 Significance of the Study

The study will be significant to residents living around major transport corridors because it will provide greater awareness of the potential implications of persistent environmental noise for sleep and general wellbeing. The findings may encourage residents and community groups to adopt practical measures for reducing exposure to excessive traffic noise where possible.

The study will be useful to public health professionals because sleep disturbance is an important health issue that can affect daytime functioning, productivity, psychological wellbeing, and quality of life. The findings may help environmental health practitioners and other health professionals understand the extent to which traffic noise contributes to sleep-related complaints within urban communities.

The study will also be useful to Lagos State environmental regulatory authorities, particularly agencies responsible for monitoring and controlling environmental noise. Findings from the study may provide additional evidence for strengthening enforcement of residential noise standards and developing targeted interventions around major transport corridors.

The study will benefit urban planners and transport authorities by demonstrating the possible health implications of locating major transportation routes close to residential communities. The findings may support consideration of noise-control measures such as traffic management, road design, sound barriers, buffer zones, enforcement of vehicle noise standards, and improved transportation planning.

The study will also be useful to local government authorities and community development organisations. They may use the findings to identify communities that require greater attention to environmental noise management and to develop community-level initiatives aimed at reducing excessive noise exposure.

The study will contribute to academic and research knowledge by adding Nigerian evidence to the literature concerning environmental noise and sleep. It may also provide a basis for future studies involving objective noise measurements, sleep-quality instruments, longitudinal designs, or comparisons between communities exposed to different levels of traffic noise.

1.7 Scope of the Study

The study will focus on noise pollution and sleep disturbance among residents living around major transport corridors in selected communities in Lagos Mainland.

The study will examine sources of environmental noise, perceived levels of traffic noise, frequency and forms of sleep disturbance, residents’ exposure to traffic noise, duration of residence, and the relationship between noise pollution and sleep disturbance.

The study will focus primarily on transport-related noise, particularly noise generated by road traffic and associated transportation activities. Other environmental noise sources such as generators, religious activities, construction, industrial activities, and commercial activities may be considered where necessary as potential background or confounding sources.

Geographically, the study will be restricted to selected residential communities located around major transport corridors within Lagos Mainland. The findings will therefore be interpreted within the context of the selected communities and will not automatically be generalised to all communities in Lagos State.

1.8 Operational Definition of Terms

Noise Pollution: Unwanted, excessive, or disturbing sound occurring at levels, times, or durations capable of interfering with human comfort, communication, rest, sleep, or health.

Environmental Noise: Unwanted sound originating from sources within the surrounding physical environment, including road traffic, commercial activities, industries, generators, construction, and other human activities.

Traffic Noise: Sound produced directly or indirectly by transportation activities, including vehicle engines, horns, tyres, braking, acceleration, exhaust systems, motorcycles, buses, trucks, and other road-transport activities.

Transport Corridor: A major route or roadway that carries substantial volumes of people, vehicles, goods, or public transportation and around which residential communities may be located.

Sleep Disturbance: Interference with normal sleep, including difficulty falling asleep, repeated awakening, difficulty returning to sleep, early awakening, poor sleep quality, shortened sleep, and daytime tiredness associated with inadequate or interrupted sleep.

Sleep Quality: The subjective and objective characteristics of sleep, including sleep duration, ease of falling asleep, continuity of sleep, nighttime awakening, and feeling rested after sleep.

Residents: Individuals who live within the selected communities around the identified major transport corridors in Lagos Mainland.

Nighttime Noise: Environmental noise occurring during the period generally associated with sleeping and nighttime rest. In this study, particular attention will be given to noise exposure during evening and night hours.

Noise Exposure: The degree to which an individual is subjected to environmental noise over a specified period, taking into consideration factors such as intensity, duration, frequency, and timing.

Major Transport Corridor: A heavily used transportation route characterised by substantial traffic movement and associated transportation activities, particularly where residential buildings and communities are located in proximity to the route.

1.9 Organisation of the Study

The study will be organised into five chapters.

Chapter One presents the introduction to the study, including the background to the study, statement of the problem, purpose of the study, research questions, research hypothesis, significance of the study, scope of the study, operational definitions, and organisation of the study.

Chapter Two will review related literature. It will discuss the concepts of noise pollution, environmental noise, traffic noise, transport corridors, sleep, sleep quality, and sleep disturbance. It will also examine relevant theoretical perspectives, empirical studies, and the identified gap in the literature.

Chapter Three will present the methodology of the study. It will discuss the research design, study area, population of the study, sample size, sampling technique, research instrument, validity and reliability of the instrument, procedure for data collection, ethical considerations, and method of data analysis.

Chapter Four will present the analysis and interpretation of the data collected from respondents. The research questions will be answered using appropriate descriptive and inferential statistical techniques, while the hypothesis will be tested at the 0.05 level of significance.

Chapter Five will present the summary of findings, conclusion, recommendations, limitations of the study, and suggestions for further research.

Project – Noise Pollution and Sleep Disturbance among Residents Living around Major Transport Corridors: A Study of Selected Communities in Lagos Mainland