Public Health Impact of Waste-Related Air Pollution in Africa: Scoping Review

1. INTRODUCTION

In the reforming world, with the expeditious development of urbanisation and industrialisation; environmental issues have become a global crisis that requires immediate interventions and has posed a major threat to the health of the population. The pollutions are solid waste, water and air-related pollution. Waste-related air pollution is identified as the most crucial environmental factor contributing to the largest negative health impact, both psychological and physiological [1, 2]. Although strategies and interventions have been proposed and implemented to purify ambient air, such as the introduction of cleaner technology and fuels and the use of greener urban greener, waste-related air pollution remains the second largest environmental factor that contributes to health comorbidities and deaths [3]. These air pollutants originate from both households and manufacturing industries. With 8.3 million deaths worldwide reported per year, 89% of those deaths occurred in low and middle-income countries, with South Asia and the western Pacific region containing the highest number of deaths. While air quality has steadily improved in high-income countries, it continues to deteriorate in low- and middle-income countries [4, 5].

In Africa alone in 2019, waste-related air pollution was associated with approximately 1.1 million mortalities. Household air pollution accounted for approximately 63% of mortality, and ambient air pollution for approximately 37% [6]. Africa is known for its mineral richness. It produces minerals such as gold, diamond, copper, bauxite, iron ore, platinum, cobalt, and others. The latest mineral production rate was approximately 912 million tons. The impact of mineral mining on air quality is a significant concern, as it contributes to ambient air pollution and adversely affects surrounding communities [7-9]. While it is important to highlight the richness of the African continent and the innovations aimed at mitigating waste-related air pollution, the socio-economic disparities among its populations present significant challenges to the successful implementation of these interventions. For these reasons, many populations cannot afford cleaner technological interventions and must instead rely on more accessible, simpler methods [10]. According to the World Health Organization, approximately 2.4 billion people rely on open fires or basic stoves fueled by polluting agents, which significantly impact air quality [11]. These people are then frequently exposed to dangerous levels of air pollution that consequently impact their health. This makes it difficult to achieve the Sustainable Development Goals (SDGs) 7 and 3, achieving synergy between climate change and health through ensuring access to affordable, reliable, sustainable and modern energy for all, and achieving good health and well-being for all ages [11]. The burden of non-communicable diseases secondary to air pollution has grown exponentially. This comprises a range of diseases affecting the respiratory, cardiovascular, neurological and other organ systems [5]. Current evidence indicates that air pollution triggers acute exacerbations of chronic obstructive pulmonary disease (COPD) and asthma and contributes to increased respiratory morbidity and mortality. Several scholars alluded that exposure to air pollution progresses one from being a healthy individual to being sick. A study conducted in the United Kingdom indicated that 5.2% of 265 506 individuals exposed to air pollution progressed from being healthy to developing at least one chronic lung disease. Additionally, 0.4% developed lung multimorbidity and 4.8% died from the exposure [12, 13]. In addition to respiratory disease development, other studies have shown that long-term exposure to air pollution is strongly associated with a higher risk of mental disorders, including schizophrenia, depression and anxiety [14].

Nonetheless, South Africa is one of the leading mineral-producing countries in Africa, known especially for its large-scale production of gold, iron, coal, and other minerals [15]. It is clear from the evidence that there is a limited existing body of evidence exploring the impact of air pollution on public health in Africa. Therefore, this study delves into dissembling the question “What are the public health impacts of waste-related air pollution in Africa?” with the sole purpose of exploring and describing the effects of waste-related air pollution on public health in Africa.

2. METHODOLOGY

We adhered to the 2018 PRISMA guidelines for Scoping Reviews (PRISMA-ScR) [16]. To facilitate knowledge synthesis through the identification of important research concepts, gaps, and evidence to support research in health practice and policymaking, a scoping review methodology was selected for this study [17-19]. Furthermore, scoping reviews employ rigorous techniques to find and evaluate pertinent research [20]. One benefit of scoping reviews is that they incorporate material that is methodologically diverse and heterogeneous. The following five stages were followed: identifying the research question, identifying relevant studies, study selection, charting the data, and collating, summarizing, and reporting the results.

2.3. Data Extraction and Analysis

The literature search yielded a total of 950 studies and 5 Gray literature. Following the abstract screening of the yielded literature, studies not relevant to the phenomenon of inquiry and duplicates were removed. Moreover, studies written in native languages were not part of the review; only English-written studies and those accessible formed part of the study. Following the full-text review of the studies, only 23 publications were included in this review. The identification process is depicted in Fig. (1). The research team designed a data extraction form, which entailed the author's name, date of publication, research design, and key outcomes of the study. Using the designed data extraction form, the research team independently extracted data from the eligible studies. Thereafter, the extracted data were compared for similarities. Upon reaching a consensus on the data extracted, the data with similar meanings were then grouped together to create themes and subthemes of the study.

Table 1.

Element	Inclusion Criteria	Exclusion Criteria
Population (P)	• These include the general population, including vulnerable groups (Children, elderly and pregnant women)	• Studies not specifically focused on the human health effects of waste air pollution.
Intervention (I)	• Studies on exposure to air waste air pollution among the general pollution • Only primary data and secondary studies (Reviews, qualitative and quantitative studies)	• Studies not focused on exposure to waste air pollution • Study protocols, editorials and comments were not part of the study
Context (C)	• Studies conducted in Africa • Studies published between 2014-2024 • English written studies • Full-text studies that were accessible on the databases	• Studies conducted outside Africa • Studies published before 2014 • Non-English studies, written in native languages • Full-text studies that were not accessible
Outcomes (O)	• Public health impacts (These include respiratory diseases, healthcare burden, and health effects)	• Studies not public health impacts

3. RESULTS

The review included 23 studies meeting the inclusion criteria. The key findings are categorized into sources of pollution, pollutants of pollution, health impacts among vulnerable populations, factors impending mitigation of air pollution and mitigation measures. Mainstream of the studies were quantitative in nature with an interest in measuring the impact of air pollution on human health, and the rest were reviews (i.e., systematic, narrative, etc.). None of the studies reviewed were qualitative. Table 2 shows the data extracted from the studies.

3.3. Understanding the Health Impacts of air Pollution Amongst the Vulnerable Populations

In the pursuit of achieving Sustainable Development Goal 3 (SDG 3), it is important to note that chronic diseases are on the rise, with some cases linked to waste-related air pollution. The burden of diseases in Africa has triplicated as the result of air pollution, lifestyle choices and other contributing factors [24]. Air pollution releases pollutants that affect the respiratory, cardiovascular, and neurological systems. It has enhanced the burden of diseases such as respiratory tract infections and chronic obstructive pulmonary disease (COPD) [5]. The WHO projects that, in the absence of appropriate measures to enhance air quality in Africa, the number of cancer cases in the continent will increase from 1.2 million in 2022 to around 2.8 million by 2050. This is attributed to the elderly population's vulnerability, greater exposure to air pollution, and inequities in healthcare resources [30]. Other than that, a study by Wichmann et al. noted an association of cerebrovascular disease mortalities with air pollutants such as PM₁₀, NO₂ and SO₂ [31].

3.3.1. Health Impact Among Children

A recent quantitative study has linked exposure to air pollutants such as PM2.5 to an estimated loss of approximately 1.96 billion IQ points among African children under the age of 10 [6]. Clearly depicting that air pollution has a certain impact on human intelligence. Studies have noted that exposure of the developing brain to air pollution during pregnancy or childhood can adversely cause brain injury, impacting the cognitive function of children [6].

Several South African studies have reported that in children, air pollution pollutants such as PM_2.5, NO₂ and SO₂ are significantly associated with respiratory illnesses and symptoms like cough, wheezing, shortness of breath and tightness of the chest. The studies signify that exposure to air pollution among children is related to the notion that children spend most of their time indoors with their mothers. In some instances, they are mostly exposed during the journey to school which exposes them to the pollutants in ambient air [23, 32, 33]. The impact of respiratory illness among children and adolescents is dependent on the length of stay in that significant area. The study of Millar et al. [28] affirmed that the presence of respiratory illness is statistically significantly associated with the number of years that particular adolescent has lived in that place. The study by Millar et al. [28] reports findings similar to those of other studies, indicating that the most commonly reported respiratory illnesses among adolescents exposed to air pollution include cough, wheezing, and doctor-diagnosed hay fever. Moreover, exposure to industrial pollution is very strongly connected to these detrimental health consequences on the respiratory system. According to the study of Naidoo et al. [37] conducted in South Africa, compared to schoolchildren from non-exposed regions, those from industrially exposed neighbourhoods had higher rates of chronic asthma and noticeable airway hyperactivity. Other than respiratory diseases, the quantitative analysis of Desouza et al. revealed that exposure to air pollutants is statistically significantly associated with stunting among children [35].

3.3.2. Health Impact Among Elderly

Only two studies from South Africa were found in the extensive literature search on the health effects of air pollution on the elderly in Africa. According to the study of Nkosi et al. [36], there is a substantial correlation between elderly people's exposure to mine dump air pollution and conditions like asthma, emphysema, chronic bronchitis, wheeze, pneumonia, and chronic cough, despite the fact that some research contends that these illnesses are most likely related to ageing and changes to the respiratory system that come with it. On the other hand, the results of the other study showed that air pollution was linked to respiratory and cardiovascular fatalities among the elderly in all three South African cities: Johannesburg, Cape Town, and Durban. There have been more reported deaths in winter seasons than in the warmer ones. The elevated levels of air pollutants in the cities, which were beyond the WHO standard, contributed to these deaths [27]. Moreover, several studies conclude that overpopulation in some places and the increased use of local resources for cooking and space heating, especially during the winter, maybe the cause of air pollution levels surpassing the WHO threshold [23, 27].

3.3.3. Health Impact Among Pregnant Women

There’s a paucity of studies delving into the health implications of air pollution among pregnant women in Africa and only a few studies delved deep into the pregnancy outcomes following exposure to air pollution in Africa. Nonetheless, in efforts to understand the impact of pollution on public health in Africa, studies have shown that in utero exposure to waste-related air pollution is associated with adverse pregnancy outcomes. For instance, a study conducted in South Africa reported that maternal exposure to waste-related air pollution such as PM_2.5 is significantly associated with preterm birth, low birth weight and gestational age [37, 38]. This was consistent with the Ghanaian cohort study that reported that exposure waste waste-related air pollution has adverse pregnancy outcomes, among which are low Apgar scores and perinatal mortality [39]. Seemingly, such negative outcomes were associated with high exposure to waste-related air pollution.

Pregnant women in African countries were reported to use diverse sources of air pollution for cooking. Among those sources are wood, petroleum gas, charcoal etc [21]. Due to these exposures, negative maternal and perinatal outcomes prevailed. Studies ascertain that the rationale behind such outcomes is that women and children are more exposed to indoor pollution than men. Some studies identified that the level of PM_2.5 was seven times higher in women than men [24]. This could be because Africa still remains a cultural continent; in some aspects of the continent, women still remain at home and be housewives; and cook for the family and care for children. As a result of that, they are exposed to higher indoor pollution that further impacts their health.

4. DISCUSSION

The analysis highlights the significant public health risks posed by waste-related air pollution in Africa. The most impacted groups are low-income neighborhoods and children. To add to the matter of waste-related air pollution, climate change is also a concern exacerbating the effects of air pollution. Dealing with climate change is a complex and challenging issue. One of the significant ways it impacts our environment is by altering the distribution and concentration of air pollutants. As global temperatures rise due to climate change, there is a notable increase in the emissions of harmful pollutants such as particulate matter (PM) and ozone. Higher ambient temperatures exacerbate the formation of ozone in the atmosphere and increase the levels of PM that are emitted from various sources [42, 43]. This increase in air pollution is not just a minor environmental concern; it has serious implications for human health. Elevated concentrations of PM can lead to a range of health problems. Furthermore, the effects of climate change on air pollution are not uniform across the globe; different regions experience varying levels of impact based on local environmental and climatic conditions. Therefore, as the climate continues to change, it is essential to understand these shifting patterns of air pollution in order to develop effective strategies for managing and mitigating its adverse health effects [42, 43]. Addressing this challenge requires a comprehensive approach that considers both the causes of climate change and the health risks associated with increased air pollution. There are, however, significant data gaps, especially in longitudinal research looking at long-term health effects. Hence, the SDGs aim to ensure comprehensive health and well-being for all by preventing premature mortalities due to non-communicable diseases. Achieving the target of SDG 7—which aims to ensure access to affordable, reliable, sustainable, and modern energy for all—is essential to realizing SDG 3, as it would help reduce air pollution and its adverse effects on human health, ultimately decreasing premature mortality [44].

Drawing from the evidence, it is clear that the impact of air pollution and its implications on human health is definitely understudied in Africa. There has been minimal focus on the sources of air pollution and the toxins they emit. The vast majority of the studies conducted in Africa focused mostly on PM_2.5 rather than on other pollutants such as volatile organic compounds, microplastics, and hazardous electronic waste emissions. Therefore, this indicates that a substantial gap remains on the health impacts of other pollutants such as volatile organic compounds, hazardous electronic waste emissions and microplastics. To reduce air pollution-related mortalities in Africa, it is crucial to thoroughly identify these sources and develop alternative strategies for mitigation. Nonetheless, the review revealed the respiratory health impacts of air pollution were similar throughout the African studies; this could be that the majority of the studies adopted the use of questionnaires to explore the exposure to air pollution using predetermined variables such as cough, wheeze, emphysema, pneumonia and asthma. Some of these conditions were common among children [23, 28, 32, 35, 36]. This raises the question, “which diseases, other than respiratory diseases, impact human health?” The WHO clearly states that air pollution affects multiple systems, including cardiovascular, neurology, and respiratory systems [5]. However, this review revealed that none of the other systems were investigated in-depth in Africa, looking at how they were impacted by air pollution. These could be attributed to a lack of resources and funding for environmental health and air pollution, as suggested by Abera et al. [24].

On the other hand, the review revealed that most of the South African cities exceeded the WHO set standard of air pollutants. Not only that, it also revealed that most of the African countries lack air quality monitoring systems. This could be because there is a lack of global legal implications surrounding the exceeding of the set standards as recommended by WHO [26, 27]. One could argue that socioeconomic injustices have an impact on exceeding the WHO-set standards, looking at the variations in developed and developing countries. For instance, countries like Germany, Italy, Belgium and Denmark have relied on varied mitigation strategies. Noting that they are more developed countries than most African countries, they rely on the use of modern solar energy technologies to reduce air pollution. Meanwhile, some countries in Africa still face power failures, corruption and economic imbalances. Modern energy is essential for these nations, especially Africa, to increase production and income generation, social advancement, and the mitigation of the major health risks associated with the usage of fuelwood, charcoal, animal manure, and agricultural waste [24, 45]. Nonetheless, currently, as a result of rapid growth in populations and poverty, most of the African countries end up relying on the burning of solid waste for cooking and saving electricity [40]. Despite the availability and establishment of policies such National Environmental Management Air Quality Act 39 of 2004, National Environmental Standards and Regulation Enforcement Agency Act 2007, and National Environmental policy aimed to ensure compliance with the standards and regulations of air quality and that the air pollutants are within the level not harmful to the health and well-being of the humans in South Africa, Nigeria and Ghana, respectively. The burning of solid wastes persists [45-48].

In the same wavelength, studies conducted in South Africa highlighted that some provinces exceed the set limits recommended by WHO. However, do not exceed the standards set by the National environmental management air quality act 39 of 2004. The exceeding of the limits is credited to the burning of biomasses in the country, particularly in winter [27, 28, 31]. The study rationale was similar to the other studies conducted in African countries like the study of Esong et al. conducted in Cameroon affirmed that air pollution was worsened by the exclusive use of wood, particularly in rural areas and sawdust as well as kerosene in peri-urban areas [41]. In South Africa, load-shedding also has a negative influence on the air quality. Load-shedding dates back to 2007, however, now it has amplified twofold [49]. The study by Pretorius et al. argues that emissions of air pollutants from South Africa were a result of poor maintenance and deterioration of the power stations [50]. Nonetheless, in the load-shedding era, companies, supermarkets and some households have relied on generators to keep their business running. This releases more emissions as the generators rely on petrol and diesel for running. Moreover, the communities relied on the use of paraffin, gas stoves and burning of solid waste to meet their basic needs within households, further impacting air quality and consequently impacting human health [49].

The problem is exacerbated in Africa by poor waste management in rural regions with limited resources, where people burn some of their waste in their backyards. The study by Godfrey et al. concluded that poor waste management is linked to weak organizational structures, a shortage of skilled personnel, inadequate resources, ineffective legislation and enforcement, low public awareness, political instability, conflict, corruption, and a lack of political will [51]. The air pollution crisis and impact is beyond only the field of energy resources; its impact extends to the environment, healthcare and finance divisions. All this makes it difficult for South Africa to achieve the SDG 3 and 7 targets. The study recommends the development of community-based interventions to strengthen compliance with South African Air quality standards involving multiple South African ministries working together towards achieving a precise goal: a safe and healthy environment for all. Public education campaigns, stronger enforcement of environmental laws, and better waste management techniques are all desperately needed. The report suggests that African laws and policies pertaining to fines and punishments for breaching predetermined thresholds be strengthened. Nevertheless, penalties and other consequences are imposed for exceeding established air pollution limits. However, monitoring systems are in place, along with other strategies aimed at ensuring compliance with established limits.

5. LIMITATIONS OF THE STUDY

The strength of this study lies in its use of a scoping review, which enables a comprehensive synthesis and critique of existing evidence to identify knowledge gaps regarding the public health impact of air pollution in Africa. This methodology facilitates an extensive search of the literature of studies ranging from qualitative, quantitative and review studies. However, the methodology also had some limitations, including the inclusion criteria. This may have led to the oversight of significant literature published before 2014. Therefore, future studies should consider conducting a comprehensive literature search beyond 2014 to determine and identify patterns and trends of the public health impact of air pollution. Furthermore, although some findings align with previous studies, the results of this review cannot be generalized to other contexts. Future research could focus on conducting comparative studies that examine the impact of air pollution in both the Global North and South. Such efforts could contribute to the development of unified, context-sensitive strategies for mitigating air pollution.

CONCLUSION

Waste-related air pollution poses a serious public health challenge in Africa. The review revealed the diverse sources and the health effects of air pollution. Among the health effects were respiratory conditions and symptoms such as asthma, chronic pulmonary obstructive diseases, sneezing, coughing and wheezing. The review indicated that the exposure to sources of air pollution was exacerbated by socio-economic injustices, corruption, and political issues, particularly in rural areas. This increases the risk of exposure to air pollution, thus increasing the risk of premature mortality among vulnerable populations. In addition, the review further highlighted little attention has been paid to other emerging pollutants that impact human health. These include pollutants such as volatile organic compounds, hazardous electronic waste emissions and microplastics. Therefore, addressing these issues requires a multifaceted approach involving policy changes, infrastructure improvements, and community engagement. Further longitudinal research studies are needed to understand the long-term health impacts fully and to develop effective mitigation strategies.

REFERENCES