Chronic respiratory diseases like chronic obstructive pulmonary disease (COPD) and asthma have a significant impact on low- and middle-income countries (LMICs) due to environmental and socio-economic factors. Globally, COPD affects 4.1% of the population, while asthma affects 3.7% [1]. Asthma is characterized by chronic lower respiratory inflammation triggered by various factors like smoke, pollutants, and allergens [2], while COPD involves irreversible airway obstruction from chronic inflammation [3]. In 2019, out of the 391.9 million individuals aged 30–79 years affected by COPD worldwide, 315.5 million resided in LMICs [4]. Furthermore, LMICs account for over 80% of asthma-related deaths [3] and 90% of COPD-related deaths [5].

In LMICs, COPD accounts for approximately 1,000 disability-adjusted life years (DALYs) per 100,000 individuals [6]. In Sub-Saharan Africa (SSA), the rate is slightly lower at 715 DALYs per 100,000 individuals [7]. Furthermore, both COPD and asthma are often underserved diseases, exacerbated by the limited availability and cost-effectiveness of asthma medications and diagnostic procedures [3]. Limited access to healthcare, exposure to pollutants, and inadequate public health policies exacerbate these conditions in LMICs [3]. Asthma medications like long-acting muscarinic antagonists (LAMAs) are often scarce and costly in LMICs, impacting treatment availability [8–10]. Prioritizing preventive interventions, early diagnosis, and improving access to essential medications is crucial in reducing the burden of these diseases in LMICs [11].

In addition to the high prevalence, climate change, characterized by rising temperatures, increased heat exposure, and varying humidity levels, is emerging as a potentially under-explored risk factor that exacerbates respiratory diseases [12]. Elevated temperatures and weather variability, linked to climate change, may increase the frequency and concentration of airborne pollutants, allergens, and ozone, potentially worsening respiratory conditions [13]. Additionally, climate change-induced weather extremes may increase dust exposure [14], whereby inhaling dust particles may cause or worsen inflammation and irritation in the airways, leading to acute respiratory reactions such as bronchoconstriction, excess mucus production, and increased inflammation. Dust often contains allergens and microbes, introducing further respiratory irritants [15]. High humidity can increase airway resistance because of its high water content and raise the physiological demand for oxygen, resulting in heightened breathlessness [16]. Additionally, high humidity may promote mold growth, posing an additional risk to both healthy individuals and those with asthma and COPD who already have sensitive airways [17]. The World Meteorological Organization (WMO) predicts a 66% chance of global temperatures rising by at least 1.5° above pre-industrial levels between 2023 and 2027, potentially leading to a significant increase in the exacerbation of respiratory diseases [18]. SSA is already established as a highly vulnerable region to the impacts of climate change and extreme weather events [19, 20], experiencing the sharpest increases in temperature and changes in rainfall patterns [21].

However, research on obstructive lung diseases, notably COPD and asthma, is both limited and unevenly distributed worldwide [22]. In the literature, we identified five systematic reviews focusing on COPD in SSA [23–27], primarily examining the prevalence of the disease [23, 25–27], inadequate supply and quality of spirometry tests and equipment [23, 24, 27], risk factors [26], and the lack of non-communicable disease (NCD) healthcare plans [23, 24]. These studies primarily focused on countries such as South Africa, Nigeria, Tanzania, Malawi, Uganda, and Ethiopia, leaving many other low- and middle-income countries (LMICs) unexplored. Asthma research in SSA is scant and primarily centered on South Africa, while studies from high-income countries often lack relevance for SSA and other LMICs due to distinct population and environmental factors [26, 28, 29]. Key knowledge gaps regarding the impact of various risk factors and climate change on the health of individuals with COPD and asthma, as well as the evaluation of the effectiveness of current interventions, remain unexplored in LMICs.

To address these knowledge gaps, we conducted a scoping review and interpreted the findings in the context of climate change. This review was guided by the following research objectives:

1. To identify major risk factors of obstructive lung diseases, specifically COPD and asthma,

The scoping review adhered to the methodological framework by Arksey and O’Malley [30], refined by Levac et al. [31], following defined steps like defining research questions, selecting studies, charting data, and reporting findings in line with Preferred Reporting Items for Systematic Reviews and Meta Analyses for Scoping Reviews (PRISMA-ScR) guidelines [32].

This review examines COPD and asthma in SSA and other LMICs, with a particular focus on the impact of climate change. It highlights key risk factors such as indoor and ambient air pollution, occupational hazards, and environmental allergens, impacting disease severity and exacerbations. Individuals with these conditions face multifaceted challenges including reduced work capacity, limited access to healthcare, social stigma, financial strain and psychological stress [87, 88]. Biomass fuel use for cooking exacerbates COPD in LMICs [87], particularly affecting women and children in rural areas [89]. Additionally, cultural practices such as burning incense, using kerosene lamps, and lighting mosquito coils contribute to higher levels of indoor pollution [89]. Interventions such as educational programs, non-physician-led treatments, and improved cookstove initiatives aim to mitigate indoor air pollution and improve respiratory outcomes. Aging also appears to significantly contribute to the prevalence of COPD in SSA. Between 1990 and 2019, the overall prevalence of COPD cases in SSA increased by 117%. However, during the same period, the age-standardized COPD prevalence rate declined by 3.3% [7]. The decline in the age-standardized COPD prevalence rate in SSA, amidst an overall case increase, might result from improved healthcare, public health policies, and a younger population.

Greenhouse gas concentrations have increased rapidly since 1850, in parallel with a 1.1°C increase in global surface temperature by 2011–2020 compared to 1850–1900 [90]. The regions that have generally contributed the least to CO2 emissions and climate change are considered to be the most vulnerable [91] and are mainly located in East, Central and West Africa, with some other regions in South Asia and Central and South America [90]. Climate change can have direct and indirect effects on health; for example, exposure to extreme heat can have indirect effects through increased transmission of food- and waterborne diseases, and direct effects through dehydration, heat stroke, and increased hospitalization and mortality from respiratory and cardiovascular diseases [92].

Although no study in the literature has explicitly examined the relationship between climate change and chronic respiratory diseases in SSA and other LMICs, it can be argued that some of the risk factors exacerbating COPD and asthma developed in this review may serve as mediators between climate change and chronic respiratory diseases. Thus, a hypothesized link between both entities in SSA and other LMICs can be deduced.

Weather variables like temperature, humidity, and precipitation play a significant role in obstructive lung diseases. Studies exhibit inconsistent outcomes, potentially attributable to climate variations or differing methodologies and settings; for example, a study conducted in Sudan’s dry Savanna region revealed an inverse correlation between temperature and asthma severity [53]. This contrasts with the common understanding that high temperatures worsen respiratory conditions [93]. The wet season with low temperatures and high humidity has been associated with increased asthma cases owing to a greater prevalence of viral infections and indoor triggers [54], which is consistent with previous research, highlighting the role of humidity and the presence of allergens and pollutants in indoor environments [94]. The combination of low temperature and humidity can cause bronchoconstriction, underscoring the importance of maintaining suitable indoor climates [95]. High humidity can exacerbate asthma by releasing allergens, highlighting the importance of indoor air quality management [95]. Although wind can increase long-range transport of pollen and pollutants [96], increased outdoor wind speed can help disperse pollutants, potentially providing protective benefits that require further investigation [95]. Human-induced climate change associated with increased greenhouse gas emissions affects weather variables, leading to heat waves, heavy precipitation and droughts in some regions [90]. Climate change may therefore have direct and indirect effects on respiratory health [97]. The included studies in this review however focused on variations of climate factors rather than extreme weather events caused by climate change. Further investigation should therefore be implemented, particularly in highly affected areas such as SSA, to study the complex relationship between climate change and chronic respiratory diseases.

In this review, other risk factors listed in Figure 4 have been shown to be associated with reduced lung function.

Ambient air pollution, divided into gaseous and particulate matter (PM) pollutants, affects both indoor and outdoor air quality. Gaseous pollutants include nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO), carbon dioxide (CO2), and volatile organic compounds (VOCs). PM pollutants, on the other hand, are classified by size and are formed from gases such as nitrogen oxides, ammonia, SO2, and VOCs [97]. In this review, studies have shown that indoor biomass and coal burning for cooking and heating in SSA and other LMICs has led to an increase in indoor gaseous and PM pollutants, and therefore to a degradation of indoor air quality. Exposure to dust and traffic-related air pollution has led to an increase in outdoor PM pollutants, resulting in poor outdoor air quality. PM pollutants have been shown to vary seasonally, with higher levels in winter due to increased dust particles and biomass burning [97]. Specifically, in SSA, excessive heat and heavy rainfall during the rainy season make outdoor cooking impractical, leading people to burn biomass indoors more frequently, resulting in poorer indoor air quality. In addition, future intense heat waves caused by climate change will lead to more wildfires, which will increase particulate matter and harmful greenhouse gases and lead to deterioration of outdoor air quality [98]. Dry and hot conditions and reduced precipitation can also lead to increased air pollution, especially ozone [97, 98], due to increased photochemical production [98]. Climate change and air pollution have also been shown to be interrelated, as PM pollutants and greenhouse gases are often co-emitted [99]; burning fossil fuels not only increases air pollution but also produces greenhouse gases, which in turn lead to extreme weather events such as droughts, heat waves and floods, which can further affect respiratory health [97]. Charcoal production and climate change are also linked through a feedback loop rather than a direct cause and effect relationship. The process of charcoal production involves deforestation and the release of greenhouse gases such as CO2 and methane, which in turn contribute to global warming [100]. In some regions affected by climate change, particularly drought, farmers may be more likely to engage in charcoal production during the dry season. In Tanzania, farmers rely on charcoal production as an alternative source of income after crop failure during the dry season [101]. This cyclical relationship will lead to poorer respiratory health. Pesticide use and climate change have also been shown to be interconnected. Rising temperatures allow for severe pest outbreaks because such conditions allow pests to survive in regions where they were previously unable to thrive [102]. In addition, the lengthening of the growing season due to higher temperatures exposes plants to pests for longer periods of time [103]. This leads to increased use of pesticides to control pest infestations. Pesticides, in turn, contribute to CO2 emissions and can disrupt soil health by killing microorganisms that play a beneficial role in carbon sequestration [104], resulting in the release of more CO2 into the atmosphere and exacerbating climate change.

Implementing cookstoves that use cleaner fuels and are equipped with a solar panel to charge the stove-fan battery [85] is an effective way that allows individuals to cook indoors during extreme heat and heavy rainfall while maintaining a good indoor air quality and generating less CO2 emissions. On the other hand, cookstoves with chimneys or a combustion chamber may reduce indoor air pollution but will still contribute to greenhouse gas emissions [83, 84]. In addition, the introduction of educational programs to increase knowledge about biomass smoke [77, 78, 80] can play a key role in reducing the burning of indoor biomass fuel but does not offer an established long-term alternative that can be afforded by the general population. These solutions can then be considered as important intermediate steps in LMICs, where resources are scarce and the use of clean energy and electric stoves is not always feasible.

Sustainable agricultural practices and predominantly plant-based diets decrease emission of greenhouse gases [98]. Adopting diets rich in antioxidants and vitamins, characteristic of Mediterranean or “prudent” diets, can significantly improve pulmonary function and reduce asthma and COPD risks [105–108]. However, over two million people suffer micronutrient deficiencies [109], especially in SSA [110]. Educational initiatives in LMICs promoting healthy diets typically utilize printed and digital materials, often based on behavior change models, and aim to engage both women and men, reflecting their distinct roles in food preparation and decision-making [111–113]. Climate change is likely to exacerbate nutrient deficiency in LMICs by affecting food security, namely accessibility, availability and food stability [114, 115]. However, other key factors contribute to food insecurity in LMICs, including limited access to modern agricultural technologies, reliance on subsistence farming, and political and economic instability in conflict zones, which disrupt agricultural production and reduce access to food [116].

It is evident that climate change plays a pivotal role in the prevalence of chronic respiratory diseases in SSA and other LMICs. This impact can be achieved directly or indirectly through various mediators, including indoor and outdoor air pollution, charcoal production, pesticide use, and nutrient deficiency. However, additional factors unique to SSA contribute to the heightened burden of chronic respiratory diseases and impede their prevention.

In certain regions in SSA where targeted asthma management protocols are lacking, managing risk factors and promoting lifestyle changes are prioritized [117]. The shortage of trained medical professionals, particularly in remote areas, poses a challenge for diagnosing and managing obstructive lung diseases. Community-based screening, technology utilization, and awareness initiatives are crucial for enhancing primary healthcare [89]. Spirometry plays a vital role in diagnosing obstructive lung diseases, but inconsistencies in diagnosis can arise from varying cutoff measures [7]. In countries like South Africa and Nigeria, spirometry use is largely confined to specialized hospitals and research settings, despite being recommended for asthma diagnosis. In Tanzania, asthma diagnosis relies mainly on clinical history and findings, while Zimbabwe lacks specific asthma diagnostic guidelines [117]. Challenges in asthma diagnosis encompass not only spirometry availability and clinician training but also equipment maintenance, electricity access, technical support, and the use of outdated equipment, necessitating comprehensive training and guidelines for healthcare workers [89, 118]. Implementing tailored pulmonary rehabilitation programs and national strategies can alleviate the burden of lung diseases in low-resource settings [89, 118, 119], although challenges like infrastructure limitations, budget constraints, political instability and healthcare workforce shortages persist in implementing WHO’s NCD management framework [11, 120].

Enhanced research, screening, and interventions are crucial for obstructive respiratory diseases in LMICs, especially in SSA, where the need is intensified by the disproportionate impact of climate change-induced global warming [119].