AIR POLLUTION AND RESPIRATORY HEALTH IN INDUSTRIAL AREAS: EVIDENCE FROM LAGOS STATE UNIVERSITY TEACHING HOSPITAL

CHAPTER ONE

INTRODUCTION

Abstract

Air pollution remains a major environmental health threat in sub-Saharan Africa, with rapidly urbanizing cities such as Lagos bearing a disproportionate burden. This study examines the relationship between air pollution and respiratory health outcomes among patients attending the Lagos State University Teaching Hospital (LASUTH). Ambient particulate matter (PM2.5 and PM10), nitrogen dioxide, and sulfur dioxide are identified as primary pollutants driving increased incidence of asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory infections in industrial neighbourhoods. Drawing on recent epidemiological data from Lagos and comparative evidence from the broader Nigerian and African literature, the chapter presents a detailed background to the study, articulates the problem statement, states the research objectives and questions, and defines key terms. The significance of the study is discussed in relation to public health policy and urban environmental governance in Nigeria.

1.1 Background to the Study

The amount of air pollution in the world is just astounding. The World Health Organization estimates that about seven million deaths are caused by exposure to polluted air each year, most of them being located in low- and middle-income countries (WHO, 2021). The growth in the rate of urbanization, expansion of industry, the increasing level of vehicular emissions, and widespread biomass burning have all come together in sub-Saharan Africa to produce the levels of air pollution that in most major urban centers far exceed the safety limits established by WHO. Lagos, Nigeria is one such leading example of this crisis.

Lagos is the most populated city in Africa with an estimated number of more than twenty one million people. Large amounts of particulate matter and gaseous pollutants continue to be deposited into the ambient air because of the city industrial zones, dense traffic corridors, waste dumpsites open to the atmosphere, and transportation systems that use high amounts of energy, among others. Research has determined that ambient population-weighted PM2.5 exposure in Lagos is around 47 micrograms per cubic metre - over four times the WHO recommended limit of 10 micrograms per cubic metre (Spadaro & Malley, 2022). This is a dangerous exposure level of particulate matter that is directly correlated with a continuum of respiratory illnesses, especially those who are at risk like children, the elderly, and those with underlying cardiopulmonary disease.

The studies carried out in the city of Lagos and other Nigerian cities always indicate the harmful impact of low quality of air on the health of people. Awokola et al. (2022) have indicated that there is an increased prevalence of respiratory diseases, including bronchitis and asthma among individuals who live in the areas having a high concentration of PM2.5 and nitrogen dioxide. More recent studies have proposed PM2.5 mortality in Lagos might explain up to 16,000 to 30,000 deaths per year, representing an approximate 18 percent of all natural deaths (Spadaro and Malley, 2022). The respiratory infections recorded in this group of children are especially high among those under five years of age: between 180,000 and 350,000 respiratory infections are recorded in this group of children.

The manufacturing plants, petrochemical plants, road construction works, and, busy seaports, characterize industrial areas in Lagos such as Amuwo-Odofin, Apapa, road construction activities, and busy seaports, which also release large amounts of pollutants such as carbon monoxide, sulfur dioxide, benzene, and fine particulate matter. Inhabitants of such communities are not only exposed to occupational exposure but also to chronic ambient exposure that causes extreme pressure to the healthcare system. Lagos State University Teaching Hospital (LASUTH), a hospital in Ikeja, is a critical referral and primary care centre that serves patients who are attracted by these highly polluted industrial regions. Knowledge about the burden of respiratory disease in LASUTH patients, and how it correlates with air quality data is hence a key to evidence-based health policy.

The connection between air pollution and respiratory health is further bifurcated by contextual issues that are specific to the urban Nigeria. Manisalidis et al. (2020) found a wide variety of pathways through which air pollutants harm the respiratory tract, such as oxidative stress, airway epithelial inflammation, and impairment of mucociliary clearance. The mechanisms are cumulative, i.e., long-term low-level exposure can lead to the deterioration of long-term lung function even without experiencing any acute symptomatic episodes. Existing stresses on an already stretched health infrastructure, including infectious disease, lack of diagnostic infrastructure and under-resourced primary healthcare, the additional burden of pollution-related respiratory disease is a significant public health challenge.

On a national scale, the situation is depicted as in Lagos. The study by Yisa, Salibi and Tzenios (2025) recorded the prevalence of respiratory health effects related to air pollution in the state of Lagos, confirming the fact that the effects of air pollution on respiratory health remain critical determinants of respiratory morbidity at the community level. Moreover, a literature review on the topic of climate change and respiratory health in Nigeria has found out that an increase in the temperature in the major urban centres such as Lagos contributes to high frequency and severity of respiratory and cardiovascular diseases (Ozoh et al., 2025). Nevertheless, with this evolving evidence base, systematic clinical research studies that relate air quality data with hospital-based respiratory health outcomes at LASUTH are relatively scarcity, which forms an important evidence gap that this study will aim to fill.

1.2 Statement of the Problem.

Air pollution in the industrial part of Lagos State is a high risk and rising threat to human lives. Although it has been established by national and international literature that the respiratory health effects of urban air pollution are real, there has been a marked lack of hospital based clinical research studies that specifically examine how patterns of pollution exposure in industrial areas in Lagos would be related to the type, severity and frequency of respiratory conditions presenting at LASUTH. Such knowledge gap restricts the capacity of clinicians, public health officers and policy formulators to formulate specific interventions.

In addition, 98% of cities in low- and middle-income countries with a population above 100,000 do not comply with WHO air quality criteria (WHO, 2021). Lagos, with its complicated tangle of industrial, vehicular, and domestic sources of pollution, represents this obstacle. Absent detailed, locally based evidence of a connection between air pollution and clinical respiratory results, the hospital management of LASUTH and the health authorities at state levels are hampered in their opportunities to prioritize respiratory care, allocate diagnostic resources, or advocate pollution control measures. This research provides an answer to these gaps by adopting a systematic review of the association between industrial air pollution and respiratory health outcomes of patients at LASUTH.

1.3 Objectives of the Study

The general objective of this study is to examine the relationship between air pollution in industrial areas of Lagos State and respiratory health outcomes among patients at the Lagos State University Teaching Hospital.

The specific objectives are:

1. To assess the prevalence and types of respiratory conditions among patients attending LASUTH from industrial areas of Lagos State.
2. To evaluate the levels of key air pollutants — specifically PM2.5, PM10, NO2, and SO2 — in identified industrial zones supplying patient populations to LASUTH.
3. To examine the association between proximity to industrial pollution sources and respiratory morbidity among LASUTH patients.
4. To identify sociodemographic and occupational factors that moderate the relationship between pollution exposure and respiratory health outcomes.
5. To propose evidence-based recommendations for reducing pollution-related respiratory disease burden in Lagos State.

1.4 Research Questions

This study is guided by the following research questions:

1. What is the prevalence and pattern of respiratory conditions among LASUTH patients residing in industrial areas of Lagos?
2. What are the ambient concentrations of key air pollutants in the industrial areas from which LASUTH patients are drawn?
3. Is there a significant association between residential proximity to industrial pollution sources and the incidence of respiratory conditions among LASUTH patients?
4. What sociodemographic and occupational characteristics predict higher respiratory disease risk among the study population?
5. What policy and clinical interventions are recommended to mitigate pollution-attributable respiratory morbidity in Lagos?

1.5 Research Hypotheses

H1: There is a statistically significant association between residential proximity to industrial pollution sources and the prevalence of respiratory conditions among LASUTH patients.

H2: Patients from high-pollution industrial areas present with more severe respiratory diagnoses than those from lower-pollution zones.

H3: Occupational exposure to industrial pollutants is a significant predictor of respiratory morbidity over and above residential exposure alone.

1.6 Significance of the Study

This study holds considerable significance for several stakeholder groups. For clinical practice at LASUTH, it will provide empirical evidence to support the triage and management of pollution-related respiratory conditions. For Lagos State health authorities and environmental regulators, the study's findings will contribute baseline epidemiological data to inform air quality management strategies and occupational health regulations. For Nigeria's health policy environment more broadly, the study contributes to building a local evidence base that can be integrated into national non-communicable disease frameworks. Globally, the study adds to comparative literature on pollution and respiratory health in rapidly urbanizing low- and middle-income contexts. Given that achieving WHO PM2.5 targets of 35 micrograms per cubic metre in Lagos would avert approximately 4,300 deaths and prevent 64,000 childhood respiratory infections (Spadaro & Malley, 2022), this research supports the case for urgent regulatory action.

1.7 Scope and Limitations of the Study

This study focuses on adult patients attending the outpatient and inpatient respiratory departments of LASUTH who reside in identified industrial areas within Lagos State. The study period covers twelve months to capture seasonal variation in air pollution levels. Key limitations include the cross-sectional nature of the clinical data, potential recall bias in patient self-reported exposure histories, and the challenge of attributing individual respiratory outcomes exclusively to air pollution in the presence of multiple confounding variables such as smoking, indoor cooking with biomass, and infectious disease co-morbidities. Generalizability beyond the LASUTH catchment area is limited but the study's findings are intended to be contextually instructive for comparable urban environments across Nigeria.

1.8 Definition of Terms

Air Pollution:

The presence of harmful substances in the outdoor atmosphere, including particulate matter (PM2.5 and PM10), nitrogen dioxide, sulfur dioxide, ozone, and carbon monoxide, at concentrations that are injurious to human health (WHO, 2021).

Particulate Matter (PM2.5 / PM10):

Fine particles with aerodynamic diameters of 2.5 micrometres or less (PM2.5) and 10 micrometres or less (PM10) that penetrate deep into the respiratory tract and bloodstream, causing inflammatory and oxidative damage (Manisalidis et al., 2020).

Respiratory Health:

A state of optimal functioning of the airways and lungs, including the absence of respiratory diseases such as asthma, COPD, and acute respiratory infections that impair breathing capacity and quality of life.

Industrial Area:

A designated or de facto zone characterized by the concentration of manufacturing, processing, and logistics activities that collectively emit significant quantities of air pollutants.

Chronic Obstructive Pulmonary Disease (COPD):

A chronic inflammatory lung disease causing obstructed airflow, characterized by emphysema and chronic bronchitis, commonly associated with long-term exposure to particulate matter and tobacco smoke.

Ambient Air Quality:

The condition of outdoor air in a given environment, measured against established standards for concentrations of pollutants to determine fitness for human habitation.

References

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