Systematic Review of Air Pollution in Ethiopia: Focusing on Indoor and Outdoor Sources, Health, Environment, Economy Impacts and Regulatory Frameworks

Research design

This review has adopt a mixed-method approach, combining air quality data and policy frameworks. It has assess the extent of pollution through secondary data on criteria pollutants level from previous studies and monitoring stations. It has also explore the prevalence of diseases linked to air pollution, such as respiratory and cardiovascular conditions. The review has focused on the effectiveness of the regulatory frameworks, such as the Environmental policies and regulations, and how well these frameworks are implemented. By integrating both data types, the review aims to provide a comprehensive understanding of the sources, impacts, and policies surrounding air pollution in Ethiopia. Figure 1 represents for research design.

Figure 1. Research design.

Air quality and air pollution

Air quality reflects the cleanliness of the atmosphere and can be significantly degraded by pollutants emitted from human activities. Air pollutants, which include chemicals, compounds, and elements, are introduced into the environment through various activities, such as the combustion of biomass fuels, vehicle emissions, and industrial processes. These pollutants are hazardous to both living organisms and ecosystems and contribute to widespread global health problems (Moriarty, 2006). The World Health Organization (WHO) estimates that nine out of ten people worldwide breathe air that is harmful to their health due to air pollution (WHO AQGs, 2021).

Ethiopia is no exception to this trend. Small-scale studies conducted in the country highlight that air pollution is becoming a major public health concern. The primary sources of air pollution in Ethiopia are indoor biomass fuel combustion, traffic-related emissions, and other outdoor pollutants (FDER, 2002; Sanbata, 2012; Graham, 2011). Research suggests that approximately 5% of acute upper respiratory tract infections in Ethiopia may be linked to air pollution exposure (MoH, 2010).

Indore air pollutants

Indoor air pollution (IAP) is a major health and environmental challenge in Ethiopia, particularly in rural and peri-urban areas where traditional biomass fuels such as wood, charcoal, and animal dung are predominantly used for cooking. This reliance on inefficient and polluting energy sources significantly contributes to poor indoor air quality, exposing households to harmful pollutants such as particulate matter (PM), carbon monoxide (CO), and volatile organic compounds (VOCs). Biomass fuel usage remains widespread, with approximately 68.7% of Ethiopian households still relying on it for cooking. Cooking practices often take place in the same room as living quarters, with 28.5% of households lacking separate kitchens. This setup exacerbates indoor air pollution, as pollutants are trapped inside, affecting all members of the household, particularly women and children, who spend more time near cooking areas (US EPA, 2022).

Indoor air pollution is a critical public health issue in Ethiopia, where more than 90% of households rely on solid fuels such as wood, cow dung, and crop residues for cooking and heating. These fuels contribute to poor indoor air quality due to inefficient combustion, which results in the release of harmful pollutants such as particulate matter (PM), carbon monoxide (CO), nitrogen dioxide (NO₂), and volatile organic compounds (VOCs).

A few studies have investigated indoor air pollution levels in Ethiopia, primarily focusing on carbon monoxide (CO) in rural Ethiopia. In particular, CO levels exceeded 4,000 ppm in homes using cow dung for fuel, and total suspended particle (TSP) levels were as high as 20 mg/m³ (Usinger, 2008). In the Gimbie, Oromia Region, respiratory suspended particulate (RSP) concentrations in homes using biomass fuels were found to be 130 times greater than air quality standards (Dyjack et al., 2005). A similar study in Shebedino Wereda, southern Ethiopia, highlighted the significant health risks posed by biomass fuels, especially for women and children (Desalegn et al., 2011).

In Addis Ababa, a cross-sectional study of 59 homes reported a 24-hour geometric mean PM_2.5 concentration of 818 μg/m³ (Sanbata, 2012), with even higher levels in homes using solid fuels (1,134 μg/m³). Another study revealed that PM_2.5 levels peak at 280 μg/m³ over a 24-hour period, with PM concentrations from coffee roasting also contributing to poor air quality (Tefera et al., 2016).

However, the findings on indoor air pollution in Ethiopia highlight several limitations. Research has focused primarily on limited regions and specific pollutants, often with outdated data. There is a need for more comprehensive, up-to-date research across diverse areas to better understand and address indoor air quality issues and their health implications.

Outdoor air pollution

Ambient air pollution, which refers to pollution in the natural outdoor environment, is a growing concern in Ethiopia and is primarily driven by rapid urbanization, industrial growth, and transportation emissions. A review of ambient air pollution in Ethiopia noted that PM concentrations reached up to 260 μg/m³ in some areas (Naidja et al., 2017), creating severe health risks.

Exposure to high levels of PM, particularly PM_2.5, can cause respiratory and cardiovascular diseases. The WHO guideline for annual PM_2.5 levels is 10 μg/m³, but studies in Ethiopian cities, such as Addis Ababa, have reported PM concentrations that far exceed these limits. A review of ambient air pollution in Ethiopia noted that PM concentrations reached up to 260 μg/m³ in some areas (Naidja et al., 2018), creating severe health risks. Vehicle emissions are a significant source of air pollution in Ethiopian cities, particularly in Addis Ababa, where traffic congestion is common and older vehicles dominate roads.

Vehicles emit nitrogen oxides (NO_x), sulfur dioxide (SO₂), carbon monoxide (CO), and particulate matter (PM). The use of diesel fuel in many vehicles exacerbates these emissions. The number of vehicles in Addis Ababa is rapidly increasing, and many of these vehicles are older models with less efficient engines and inadequate emission controls. A study in Addis Ababa revealed that gaseous pollutants such as NO₂ and CO exceeded safe limits, with NO₂ concentrations ranging between 21 and 50 μg/m³ (Kumie et al., 2021). Additionally, diesel consumption is projected to increase by 285% from 2015 to 2035, worsening the situation (Keil et al., 2010).

Industrial activities in Ethiopia, particularly in Addis Ababa, contribute significantly to ambient air pollution. Key industries, including textile manufacturing, food and beverage processing, and construction materials, emit pollutants such as sulfur dioxide (SO₂), nitrogen oxides (NO_x), volatile organic compounds (VOCs), and particulate matter (PM) (World Bank, 2019 & Gizaw et al., 2022). These emissions contributed to elevated PM and gaseous pollutant levels in Ethiopian cities. Emissions from manufacturing plants and ongoing construction activities in urban areas such as Addis Ababa increase PM levels. In addition to local emissions, the use of outdated technology in industries also limits pollution control.

Biomass burning produces high levels of carbon monoxide (CO), particulate matter (PM), and other pollutants. Studies show that biomass burning can increase CO levels to 20 mg/m³ in some regions of Ethiopia, exceeding WHO guidelines (Kumie et al., 2021). In rural areas, the burning of biomass for household energy is a major contributor to air pollution. This also leads to greenhouse gas emissions and contributes to climate change, with road and land use accounting for 79% of greenhouse gas emissions in rural areas (Dawson & Spannagle, 2015).

Studies conducted in Addis Ababa have shown that PM₁₀ and PM_2.5 concentrations regularly exceed WHO limits. A study at Black Lion Hospital reported NO₂ concentrations ranging from 21-50 μg/m³, indicating the significant impact of traffic and industrial emissions (Kumie et al., 2021). Research on air pollution in rural Ethiopia is sparse, but biomass burning and dust from land use changes contribute to poor air quality in these regions. A study found that road and land use activities accounted for 79% of greenhouse gas emissions in rural areas (Dawson & Spannagle, 2015).

However, the findings on ambient air pollution in Ethiopia have several limitations. Studies have focused mainly on major cities, leaving gaps in rural and smaller urban areas. The data are often outdated, and there is a lack of research in rural areas and on seasonal variations. While most related research has focused on particulate matter and common pollutants, other harmful pollutants have been underexplored. Additionally, there is insufficient analysis of health impacts, technological and regulatory challenges, and public awareness. Addressing these limitations is essential for a comprehensive understanding and effective management of air pollution in Ethiopia.

Source

A source apportionment study of both indoor and outdoor pollution has shown the following conclusions:

Biomass fuels, such as wood, charcoal, and animal dung, are commonly used for cooking and heating in rural and urban areas. The combustion of these fuels in poorly ventilated spaces releases harmful pollutants such as PM_2.5, carbon monoxide (CO), and other toxic gases, posing serious health threats to households (WHO, 2006).

Carbon monoxide (CO): CO exposure in households using biomass fuels is particularly concerning. Studies have shown CO levels exceeding 4,000 ppm in homes burning cow dung, as observed in rural Tigray (Usinger, 2008).

Particulate matter (PM): Particulate matter, particularly PM_2.5, is one of the most harmful pollutants. In Addis Ababa, PM_2.5 concentrations in households using solid fuels were reported to reach a geometric mean of 1,134 μg/m³ (Sanbata, 2012). These levels far exceed the WHO and US EPA standards and can lead to respiratory and cardiovascular diseases.

Building Materials and Furnishings: In Ethiopia, older buildings may still contain asbestos as insulation and lead-based paints, which are potential sources of indoor air pollution. However, research on the contribution of building materials to the indoor air quality in Ethiopia is limited.

Household Cleaning and Maintenance Products: While not a major focus of Ethiopian indoor air quality studies, household cleaning products and air fresheners used in urban areas can release VOCs, contributing to indoor air pollution. These products may exacerbate respiratory conditions, especially in homes with poor ventilation.

Biological pollutants: Mold, dust mites, and bacteria are common biological pollutants in Ethiopian households, particularly in rural areas where housing may be poorly ventilated or prone to damp conditions. Additionally, pet dander and livestock kept near homes contribute to indoor biological pollutants, leading to allergic reactions and respiratory infections.

Radon: There is limited research on radon exposure in Ethiopia, but this topic is a potential concern, particularly in highland areas where geological conditions may contribute to radon seepage into buildings.

Pesticides: Pesticides used in homes, particularly in rural and agricultural areas, contribute to indoor air pollution. These chemicals pose risks to human health when inhaled, especially in enclosed spaces with inadequate ventilation.

As reported previously (Ethiopian News Agency &EFCCC, 2021), in Ethiopia, the main sources of outdoor air pollution include emissions from aged and fuel-inefficient vehicles, industrial activities, open trash burning, and dust from construction. The use of biomass for home heating and cooking also contributes significantly to pollution, particularly in urban areas such as Addis Ababa. Rapid urbanization, industrial growth, and lifestyle changes have exacerbated these issues, with air pollution expected to increase unless additional effective measures are implemented. Pollutants from outdoor sources, such as carbon monoxide (CO), ozone (O₃), sulfur dioxide (SO₂), and particulate matter (PM), can infiltrate homes through doors and windows. In urban areas such as Addis Ababa, outdoor air pollution is exacerbated by traffic and industrial emissions, which can elevate indoor air pollution levels. Additionally, burning practices in rural areas contribute to particulate matter entering indoor environments.

Occupant activities: Indoor activities such as cooking, smoking, and roasting coffee contribute significantly to indoor air pollution in Ethiopia. Traditional cooking practices using open fires or inefficient stoves generate high levels of particulate matter. For example, PM₄ concentrations during coffee roasting in Addis Ababa were found to be particularly high, contributing to poor indoor air quality (Keil et al., 2010).

The study of source apportionment of indoor and outdoor pollution in Ethiopia has several limitations. It primarily focuses on biomass fuels without fully addressing other indoor pollutants, such as those from building materials, cleaning products, or biological sources. Research on pollutants such as radon and pesticides is limited, and the interaction between indoor and outdoor pollution has not been extensively studied. Most related research has been concentrated in specific areas, with insufficient data on other regions or seasonal variations. However, further research is needed to better understand the impact of various indoor activities on air quality.

Health impact

Air pollution is a leading cause of morbidity and mortality worldwide, accounting for approximately 7 million premature deaths annually (Cohen et al., 2017). Among low- and middle-income countries, 90% of these deaths occur, with sub-Saharan Africa facing particularly severe impacts due to rapid urbanization, biomass fuel usage, and weak regulatory frameworks. In Africa, outdoor air pollution causes approximately 176,000 premature deaths annually, while household air pollution from biomass cooking fuels results in 400,000 deaths each year (Fisher et al., 2021).

In Ethiopia, air pollution is a critical public health challenge. According to the Ministry of Health (MoH, 2018), air pollution was the third leading risk factor for premature deaths in 2017, accounting for nearly 8% of total deaths or approximately 41,000 deaths. By 2021, air pollution was responsible for almost 10% of the deaths in the country, with outdoor particulate matter (PM) ranking as the seventh leading risk factor for deaths and household air pollution (HAP) ranking first (HEI, 2024). The leading health risks in Ethiopia include child and maternal malnutrition, air pollution, unsafe water and sanitation, and high systolic blood pressure. Among these, air pollution is estimated to have contributed to more than 76,000 deaths in 2021, marking a substantial increase from previous years. The continued reliance on biomass fuels, combined with rapid urbanization and growing vehicle emissions, exacerbates the air pollution problem in Ethiopia.

Acute respiratory infections (ARIs) are a major cause of morbidity and hospital admissions in Ethiopia. A survey study reported approximately 1.26 million cases of acute upper respiratory infections, constituting 5% of the total cases and accounting for 7% of hospital admissions in 2011 (MoH, 2011). A high incidence of ARIs is closely associated with poor air quality, particularly from household air pollution caused by the burning of biomass fuels. Children are especially vulnerable to lower respiratory tract infections, such as pneumonia, which are closely linked to high levels of PM2.5. Tuberculosis, respiratory infections, and asthma together accounted for 17% of the deaths in Addis Ababa hospitals between 2006 and 2009, with acute lower respiratory tract infections being the leading cause (Misganaw et al., 2012a, 2012b). Noncommunicable diseases such as chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD), stroke, and lung cancer are strongly correlated with long-term exposure to PM2.5. A study conducted in Addis Ababa from 2006 to 2009 revealed that 51% of deaths were attributed to NCDs, with air pollution being a significant risk factor (Misganaw et al., 2012a). Air pollution also affects pregnancy outcomes, contributing to premature birth, low birth weight, and increased neonatal mortality. The burning of biomass fuels in poorly ventilated homes disproportionately impacts pregnant women, exposing them to high levels of harmful pollutants.

Research on the impact of health on air pollution in Ethiopia has key limitations. This approach highlights severe health risks but lacks detailed data on specific pollution sources and their direct effects. This study does not fully address regional variations or the effectiveness of mitigation measures. More comprehensive, region-specific research is needed to better understand and address the health impacts of air pollution.

Economic impact

Air pollution is a significant environmental issue with profound economic consequences. The economic impact of air pollution includes healthcare costs, lost productivity, and damage to infrastructure. According to the World Bank (2022), in Ethiopia, air pollution represents a major economic challenge with the following key impacts:

Healthcare Costs: The economic impact of air pollution-related diseases in Ethiopia is estimated at $3 billion, which is approximately 1.16% of the country’s GDP. This includes direct healthcare costs associated with treating diseases caused by air pollution.

Lost Productivity: Air pollution results in reduced labor productivity due to health issues and premature deaths. The broader economic implications include decreased workforce efficiency and increased absenteeism due to illness.

Agricultural and Infrastructure Costs: While specific data on agricultural losses and infrastructure damage are less detailed, it is likely that air pollution negatively affects agricultural yields and accelerates infrastructure deterioration.

This economic impact study on air pollution in Ethiopia has several limitations. While significant costs related to healthcare, productivity loss, and potential agricultural and infrastructure damage have been highlighted, detailed data on the specific effects of air pollution on agriculture and infrastructure are lacking. Additionally, the study does not fully account for the broader economic implications beyond direct costs. More detailed and comprehensive data are needed to better quantify and address the full economic impact of air pollution in Ethiopia.

Environmental impact

Air pollution poses significant environmental threats, impacting ecosystems, climates, and overall environmental health. According to the 2015 MFCCC, (Tessema, Z. K., & Fekadu, G. 2021), in Ethiopia, air pollutants, particularly particulate matter (PM) and sulfur dioxide (SO₂), can affect plant health by reducing photosynthesis and causing soil acidification. This can lead to reduced agricultural yields and soil degradation. Pollutants can be deposited into water bodies, leading to issues such as eutrophication, which can harm aquatic life and disrupt ecosystems. The combustion of fossil fuels contributes to the release of greenhouse gases such as carbon dioxide (CO₂) and methane (CH₄), which exacerbates climate change. In Ethiopia, where agriculture is a major part of the economy, changes in climate can impact crop productivity and food security.

However, research on the environmental impacts of air pollution in Ethiopia is limited. The survey noted effects on plant health, soil, water bodies, and climate but lacked detailed data on specific impacts and regional variations. Additionally, studies have not thoroughly analyzed how air pollution affects crop productivity and food security. More comprehensive research is needed to better understand these environmental consequences.

Regulatory framework

Ethiopia has a regulatory framework aimed at addressing air pollution, although this framework is still evolving. The main components of this framework (FEPA, Ethiopian Environmental Policy (1997), Environmental Impact Assessment Proclamation No. 299/2002, Air Pollution Control Proclamation No. 286/2002 & MEFCCC) include the following:

Ethiopian Environmental Policy (1997): Provides a broad framework for environmental management, including air quality. It emphasizes sustainable development and the integration of environmental considerations into policy-making.

Federal Environmental Protection Authority: Oversees environmental protection efforts, including air quality management. It is responsible for enforcing regulations and standards related to air pollution. However, week in making an action

National Standards for Air Quality: Set by the EPA, these standards aim to limit the concentration of pollutants in the air, including particulate matter (PM10, PM2.5), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and carbon monoxide (CO). However, this year was formulated in 2003.

EIA Proclamation No. 299/2002: Requires an assessment of potential environmental impacts, including air quality, for new projects. This helps in mitigating adverse effects before project implementation.

Proclamation No. 286/2002: Focuses on the control of air pollution and the establishment of air quality monitoring systems.

Industrial Pollution Control: Regulations related to emissions from industrial activities are in place, aiming to control and reduce pollutants released by industries. However, after one week of implementation.

Air quality monitoring

Ethiopia has significantly expanded its air quality monitoring in recent years but still faces challenges due to historically limited real-time infrastructure. Rapid urbanization, increased traffic, and industrial activities in cities such as Addis Ababa have worsened air pollution, impacting health, the environment, and the economy. The Environment, Forest, and Climate Change Commission (EFCCC), alongside various partners, including the UNEP and the World Bank, is working to improve monitoring systems and implement new measurement stations in urban areas. Despite these advancements, air quality monitoring in Ethiopia has limited coverage. In Addis Ababa, existing stations measure basic pollutants such as PM_2.5, PM₁₀, NO₂, SO₂, O₃, and CO, but expanding the monitoring network is ongoing. The main challenges include inadequate infrastructure, a lack of real-time monitoring systems, and low public awareness. The air quality monitoring network in Ethiopia is still developing, with devices from the Ethiopian Meteorology Institute (EMI), the U.S. Diplomatic Posts (USDP), the GEOHealth Hub, and various low-cost sensors installed across the city. Despite these efforts, many sensors face functionality issues; as a result, air quality data are limited in the country.

Although the country has a regulatory framework and has made efforts to expand air quality monitoring, challenges persist. The existing policies and standards, such as those outlined in Ethiopian Environmental Policy and Proclamations No. 299/2002 and No. 286/2002, face issues with outdated regulations and weak implementation. Monitoring infrastructure is still developing, with limited coverage and real-time data capabilities. Additionally, many monitoring devices face functionality issues, leading to incomplete and sporadic air quality data. More effective enforcement of regulations, improved monitoring infrastructure, and increased public awareness are needed to address these limitations.

Policy recommendations

Enhance Air Quality Monitoring Infrastructure: Expand the network of air quality monitoring stations across Ethiopia, focusing on both urban and rural areas to ensure comprehensive coverage. Invest real-time monitoring systems and maintain existing equipment to improve data accuracy and availability.

Promote Cleaner Cooking Technologies: Encourage the adoption of cleaner cooking solutions such as improved stoves and liquefied petroleum gas (LPG) through subsidies and public awareness campaigns. Research into affordable and efficient alternatives to biomass fuels is needed, particularly in rural areas.

Strengthen Regulatory Frameworks: Update and enforce air quality standards to align with current health guidelines and international best practices. Shorter vehicle emission standards should be implemented, and cleaner public transportation options should be invested in to reduce traffic-related air pollution.

Improve Public Awareness and Education: Launch nationwide awareness campaigns to educate the public about the health risks of air pollution and promote behaviors that reduce exposure. Air quality education should be incorporated into school curricula and community programs.

Integrate Health, Economy and Environmental Data: Establish a comprehensive system to integrate air quality data with health surveillance information, enabling targeted interventions and better assessment of pollution impacts on public health and the economy.

Support Research and Development: Fund research into the sources, effects, and mitigation of air pollution specific to Ethiopia, including studies on indoor air pollution, biomass burning, and industrial emissions. Explore innovative technologies and strategies used in other countries that could be adapted for use in Ethiopia.

Future research directions

Indoor Air Pollution Studies: Conduct extensive research on indoor air pollution levels across different regions, especially focusing on the impact of biomass fuels and other common household practices. Investigate the effectiveness of various indoor air quality improvement interventions in Ethiopian contexts. In addition, some studies have evaluated outdoor air pollution.

Outdoor Air Pollution Studies: Investigate major outdoor pollution sources, such as vehicle emissions, industrial activities, and biomass burning. Evaluate the health effects and environmental impacts of outdoor pollution on vulnerable populations and ecosystems. Long-term data were analyzed to track changes in air pollution levels and assess the effectiveness of regulatory measures.

Health impact assessments: To study the specific health impacts of different air pollutants in Ethiopia, including respiratory and cardiovascular diseases, and their associations with air quality levels. The long-term health effects of air pollution exposure should be examined, particularly in vulnerable populations such as children, elderly individuals and pregnant women.

Economic analysis: Evaluate the economic costs associated with air pollution, including healthcare expenses, lost productivity, and damage to infrastructure. The economic benefits of implementing air pollution control measures and cleaner technologies should be assessed.

Policy Effectiveness Evaluation: Assess the impact of existing air quality regulations and programs to identify strengths and areas for improvement. Case studies of successful air quality management strategies from other countries should be explored, and their applicability to Ethiopia should be evaluated.

Environmental Impact Studies: Research the environmental consequences of air pollution, including its effects on soil, water, and biodiversity. The relationship between air pollution and climate change should be studied in the Ethiopian context, particularly focusing on how air pollutants contribute to greenhouse gas emissions and climate-related impacts.