Knowledge of air pollution sources is crucial for air pollution mitigation and policy making. Due to multiple constraints, air quality monitoring is often limited in lower- and middle-income countries, where rapid urbanisation and industrialisation are causing the local population to be exposed to dangerous concentrations of pollutants. The use of low-cost sensor (LCS) networks offers a more affordable alternative and a stepping stone in monitoring and assessing the air quality where research-grade equipment is currently unavailable. The present study re-assesses a previously published dataset of particulate matter (PM) concentrations in Ile-Ife, Nigeria, for source identification using k-means clustering and triangulation of the sources. The method identified six clusters based on particle number concentration profiles, separating daytime and night-time conditions, as well as the periods when local or regional sources had the greatest effect on the local air quality. The highest concentrations of particulate matter in Ile-Ife were associated with stagnant conditions and at the sites closer to the industrial activities in the area, for which the PM concentrations were about 10 times higher than the daily average (mean ± standard deviation PM2.5 30.6 ± 40.7 µg m-3, and PM10 83.4 ± 259.2 µg m-3). The methodology also provides information on the circumstances when cleaner conditions occur, and these were found during the daytime with higher wind speeds from the southwest (SW), when PM concentrations were significantly lower than the average at all sites (PM2.5 11.5 ± 4.7 µg m-3, and PM10 37.2 ± 26.0 µg m-3), but still above the annual limits recommended by the World Health Organization (WHO). Additionally, the polluting effects of the urban background as well as from traffic were identified, and the atmospheric conditions which increased the importance of these sources were elucidated.
Air pollution remains a major environmental health concern in South Africa, particularly in the Highveld Priority Area (HPA), where multiple coal-fired power stations, heavy industry, and household solid fuel use contribute to sustained poor air quality. This review systematically assessed the peer-reviewed evidence on air pollution and health in the HPA to establish a baseline of research, identify gaps, and inform future policy and scientific priorities. Following PRISMA guidelines, we searched four bibliographic databases and key journals for English-language studies published up to October 2024. A total of 130 papers met the inclusion criteria: 98 focused on air quality only, 19 on health only, and 13 addressed both air quality and health outcomes. Air quality studies span more than four decades, documenting trends in criteria pollutants such as SO₂, NO₂, PM₁₀, PM₂.₅, and O₃, with recent analyses highlighting the HPA as one of the world’s NO₂ and O₃ hotspots. Health studies, mostly post-2014, primarily investigated respiratory outcomes, with a few extending to cardiovascular disease and congenital anomalies. Most relied on self-reported health data, while only one study used objective spirometry. Studies combining air quality and health data are few, methodologically limited, and largely unable to establish causal relationships. Nevertheless, evidence consistently suggests that HPA residents—especially children, adolescents, and the elderly—are at heightened risk of respiratory morbidity. The review highlights critical research gaps, including insufficient use of personal exposure monitoring, limited objective health assessments, and a narrow focus on respiratory outcomes. We recommend coordinated, large-scale, interdisciplinary studies leveraging the HPA as a natural laboratory to advance understanding of air pollution–health linkages. Strengthening ambient monitoring networks, integrating indoor and outdoor exposure data, and expanding research beyond respiratory effects are essential to guide effective interventions and uphold the constitutional right to a healthy environment in South Africa.
In December 2025, Development in the Anthropocene: The tough task of working towards planetary well-being with low-income households became available electronically on the UJ Press platform. It is now in print. Although the book has a South African setting, the peer-reviewed scholarly chapters carry insights that are applicable to other jurisdictions. The point of the relevant chapters is clean air for low-income households.
This study investigates how quality of life (QoL) indicators can be integrated into South Africa’s air quality management system to support a just transition. Drawing on a grounded, context-specific QoL framework developed through South African policy analysis and community-based research, the study maps social indicators across five capital domains: economic, human, social, natural, and political. A qualitative synthesis of global literature reveals a geographic bias toward global North contexts, underscoring the need for locally relevant approaches. By aligning QoL indicators with existing governance instruments, the research identifies gaps in participatory and equity-focused mechanisms. It proposes a multidimensional framework for more inclusive, measurable, and socially responsive air quality governance. The findings position this study as a critical contribution to context-sensitive environmental planning and just transition discourse in the global South.
Gauteng is South Africa’s largest urban and manufacturing hub and most populous province. There is widespread non-compliance with national ambient particulate matter (PM) standards in the province. This review aims to comprehensively assess strengths and weaknesses in the existing body of knowledge on the factors that affect PM concentrations in Gauteng. A systematic literature review of relevant studies is performed based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analysis) method, to synthesise our understanding of local and regional sources of PM and its precursors, the transport mechanisms, and the spatial and temporal variations in PM2.5 concentrations. While it is known that the major sources of PM in Gauteng are industrial and mining activities, household fuel burning, vehicles, aeolian dust and biomass burning, their relative contributions to ambient PM concentrations have not been satisfactorily quantified. Long-range transport of pollutants is governed by the position of the continental anticyclone, but it is not known how this will change in association with climate change, or how urban heat islands over built-up areas affect pollution transport. The poor availability of PM measurements at ambient air quality monitoring stations hampers the understanding of long-term trends in PM concentrations. Satellite observations and chemical transport models offer great promise in assessing temporal and spatial variations in PM concentrations. It's recommended that data availability at a core subset of Gauteng's ambient air quality monitoring network be improved; that source apportionment studies be conducted in densely populated areas where exposure levels are high; that PM and precursor emissions from vehicles be quantified; and that the environmental justice implications of the high spatial variability in PM concentrations be investigated. Prioritisation of these areas of research will aid in the design of evidence-based interventions to reduce exposure to harmful pollution levels in southern Africa’s most densely populated region.
Air pollution is a major threat to human health globally. In 2021, the World Health Organization (WHO) reported that 7 million prematuredeaths, mainly from non-communicable diseases, are due to air pollution. Air quality studies on PM2.5 and its composition are lackingin South Africa and Africa. To find ways to reduce PM2.5 sources and its associated health impact in the Bojanala Platinum DistrictMunicipality (BPDM), North West province, South Africa, it is necessary to determine PM2.5 concentrations, its chemical compositionand distant air pollution source areas in this area. PM2.5 filter samples were collected manually during 24 hours every sixth day from 10May 2021 and 4 June 2022 in a residential area in Bapong. Bapong is located in the BPDM. The average PM2.5 level during the samplingperiod was 21 μg.m-3 (range: 2.0 to 78 μg.m-3), which is higher than the yearly WHO guideline (5 μg.m-3), and South African NationalAmbient Air Quality Standards (SANAAQS) (20 μg.m-3). The 24-hour PM2.5 levels exceeded the daily WHO guideline (15 μg.m-3) and dailySANAAQS (40 μg.m-3) on 27 and nine occasions, respectively. The highest PM2.5 levels were observed during the cold autumn season(78 μg.m-3: May 2022). Soot levels ranged from 0.1 to 8.0 m-1 × 10-5 with an annual average of 1.8 m-1 × 10-5. The black carbon (BC) levelsranged from 0.1 to 6.0 μg.m-3 with an average of 1.3 μg.m-3. The average level of organic carbon (OC) was 1.4 μg.m-3 (range: 0.1 to 5.0μg.m-3). Most of the geographical air masses were found to be originating inland (65%). This pioneering study in Bapong provideskey insights into the seasonal and weekly variation of PM2.5, soot, BC and OC concentrations, distant air pollution source areas thatcontribute to their concentrations and their potential public health risk in the area.
This study evaluated indoor air pollution in urban Tanzanian kitchens reliant on solid biomass fuels (SBF), focusing on pollutantconcentrations and structural determinants. Using a cross-sectional design in Morogoro Municipality (n=153 kitchens), real-timemeasurements of suspended particulate matter (PM2.5, PM10), carbon monoxide (CO), relative humidity, and temperature wereconducted alongside assessments of kitchen size, wall material, ventilation, and location during the end of the rainy season (April–May 2024) to minimize temporal variability and isolate pollutants from cooking activities.During cooking periods, PM2.5 24-h TWA concentrations had a median of 30.9 μg/m³ (8.8–121.9 μg/m³), with 63% of kitchens exceedingthe WHO guideline, PM10 were below WHO and TBS limits but exceeded guideline values in 12% of kitchens. 30% of kitchens hadrelative humidity ≥60%, 75% exceeded thermal comfort limits, and CO concentration in all kitchens surpassed WHO/TBS 1-h guidelines(60 ppm > 2-fold higher vs. 26 ppm 1-h; all p<0.001), with some kitchens recording levels up to ten-fold higher, indicating a substantialrisk of acute exposure. Kitchens situated within dwelling houses had higher PM2.5 (251 vs. 235 μg/m³) and PM10 (269 vs 237μg/m³)than detached (p<0.05); block-brick walls were hotter (35±4 °C) and drier (33±10%) than mud walls (p<0.05). PM2.5 and PM10 correlatedstrongly (r=0.921, p<0.001), signaling combustion co-exposure.These findings reveal hazardous pollution levels elevating respiratory/cardiovascular risks, especially for women/children, drivenby SBF and poor kitchen design. Interventions should promote cleaner fuels, efficient stoves, and ventilation per Tanzania's CleanCooking Strategy (2024-2034). Longitudinal seasonal studies are needed to refine exposure estimates and inform sustainable policyintervention strategies.
Across Africa, national and sub-national governments, community-based organisations, and research institutions are responding to the critical need for air quality data–a prerequisite for targeted, evidence-based clean air policy action–by setting up monitoring networks. However, the data generated by these monitoring networks isn’t magically ready for analysis and action. Projects need what’s called a Data Management System (DMS), the software that handles behind-the-scenes functions, such as data ingestion, aggregation, harmonisation, storage, quality control, validation, sharing, and more, to enable interpretation and application of the data for various use cases. The Clean Air COMPASS project was launched in December 2024 by the project leads, whose first task was to engage a Community of Practice for Air Quality Systems (COMPASS), a network of core partners representing different geographies and data expertise with established credibility to secure the stakeholder feedback needed to build an open-source DMS.
This study examines the role of the turbulent Schmidt number (Sc) in shaping the dynamics of aeolian sand transport, with a particular focus on turbulent energy dissipation and particle diffusion. Using a mixture model framework and direct numerical simulations, we investigate both suspension (D = 2 μm) and saltation (D = 250 μm) modes under controlled wind tunnel conditions. Results demonstrate that Sc strongly influences diffusion coefficients and dissipation rates, with a stable convergence identified in the range Sc = 0.7–0.9. This interval represents a physically meaningful threshold where the turbulence structure of air–sand flows remains relatively insensitive to Sc variations. The findings provide not only a refined parameterization of aeolian transport but also a basis for improving predictive models of dust storms, atmospheric pollutant dispersion, and environmental risk assessments. This work highlights the importance of treating Sc as a tunable parameter in environmental fluid dynamics rather than as a fixed constant.
This study investigates the elemental composition of atmospheric dust collected from both outdoor (roadside) and indoor environments across five distinct geographic areas in Lagos State, Nigeria, to assess environmental contamination and associated health risks. Surface dust was collected using a soft brush and dustpan, followed by acid digestion and analysis using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). A total of 34 elements were quantified, with results indicating significant spatial variation in concentrations. Notably, elevated levels of lead (Pb) and cadmium (Cd) were detected, suggesting contributions from industrial activities, vehicular emissions, and other anthropogenic sources. In contrast, concentrations of zinc (Zn), copper (Cu), and nickel (Ni) remained within permissible limits, reflecting lower pollution levels in certain areas. Health risk assessments revealed that the incremental lifetime cancer risk (ILCR) for both adults and children exceeded the U.S. EPA's acceptable thresholds (10⁻⁶ to 10⁻⁴), particularly in high-traffic zones. The findings underscore the need for targeted pollution control measures and provide essential data to inform air quality management and public health strategies in Lagos State.
This research presents a comprehensive evaluation of air pollution levels linked to vehicular traffic in Bou-Ismail using a statistical methods to examine correlations, trends, and relationships between pollutant concentrations and meteorological variables, as well as to assess factors contributing to particulate pollution in the Bou-Ismail area. A monitoring station was established along a major roadway for six months from December 16, 2015, to June 29, 2016, to assess particulate matter (PM2.5 and PM10), ozone, sulphur dioxide, carbon monoxide, nitrogen oxides, and volatile organic compounds to investigate the factors and variables that contribute to particulate pollution in the Bou-Ismail area. The average concentrations of SO2 and NO2 for the campaign were equal to 0.14 and 12.07 ppb, respectively, respecting the national guidelines. Concentration in this study for PM10 and PM2.5 were 20.2 and 8.9 µg/m3. The predictive models applied to evaluate particulate matter concentrations demonstrated strong performance, yielding coefficient of determination (R²) values exceeding 0.83. No correlation was seen between PM and WS (wind speed), while O3 concentration was positively correlated with temperature. PC1 (35.38%) indicates that cars contribute the most to local air pollution, with significant particle and petrol emissions but low VOCs. PC2 (21.75%) relates CO to vehicles, while buildings have the most VOCs, followed by transport and agriculture. The PM2.5 Air Quality Index (AQI) exceeded guideline thresholds on more than 42 days out of 196 days recorded, which indicates that the air quality is unhealthy to very unhealthy for sensitive groups. The hazard quotient (HQ) in our investigation was below 1, which signifies a tolerable level of risk. The average monthly ELCR (Excess lifetime cancer risk) of PM2.5 in this research surpassed the recommended guideline value of 1.0E-06. According to HYSPLIT back-trajectory investigations, western European air pollution reached western Algeria via Portugal and southern Spain. Mauritanian air masses may have carried Saharan dust to Mali and south Algeria. The second to last phase saw eastern Algiers air masses migrate north into the Mediterranean, signifying pollution export. PM2.5 and PM10 concentrations increase in westerly and southerly airflows.
After the 1st Chemical Weather and Chemical Climate conference (CWCC) held in Shanghai in 2023, the 2nd CWCC conference was held at the University Mohammed VI Polytechnic (UM6P, https://cwcc2025-conference.org/) in Morocco during 14-16 October 2025.
The third edition of the CLEAN-Air Forum, held in Nairobi (Kenya) between 15-17 July 2025, under the theme of Partnerships for Clean Air Solutions, brought together more than 390 participants from more than 35 countries. The event was convened by the Nairobi County Government in partnership with the World Resources Institute-Africa, AirQo and the Health Effects Institute. The forum is the flagship event of the Africa Clean Air Network (AfriCAN) and serves as a platform to convene policymakers, academia, industry, media and civil society organisations to foster knowledge sharing, collaboration, and cross-border partnerships to address air pollution across Africa.
This study investigated the physicochemical properties of particles generated from different combustion phases. A total of three chicken grilling/ braaiing stalls were selected for physicochemical profiles of charcoal combustion particles. The samples were collected 1.5 m above the ground and 0.8 m away from the stove. Samples were collected in triplicate to minimize uncertainty making a total of 27 data points (in triplicates) for studying particle size distribution, mass and number concentration. Monitoring of particles was done using a real-time Nanozen DustCount 9000 Personal Dust Monitor. Samples for chemical assessments were collected on 37 mm PVC filters with a pore size of 5 µm. A Gilair pump at a flow rate of 2.2 l/minute was used to draw in the air over a monitoring campaign of 2 hours and 20 minutes per burning cycle. A PM2,5 cyclone with a PM4 cut-off point at 50% was attached to a cassette to isolate larger particles. The filters were subjected to acid digestion as a sample preparation step prior to analysis inductively coupled plasma mass spectrometry (ICP-MS). Coking phase had the highest number of particles with 2.20E+08 ± 3.31E+07#/cm3 (48%), followed by flaming with 1.54E+08 ± 8.60E+07#/cm3 (34 %) and ignition with 1.09E+08 ± 3.38E+07#/cm3 (18 %). Submicron particles contributed the highest number concentration in all phases. Using mass concentration, coking had the highest contribution of 41.6± 15.0 µg/m³ (38.0%), ignition 35.5± 8.8 µg/m³ (32.4%) and flaming 32.3± 2.1 µg/m³ (30 %). Aluminium was the highest emitted element with 1.3E-01µg/m³ (43 %), followed by zinc 7.7E-02 µg/m³ (25 %), magnesium 7.0 E-02 µg/m³ (22 %) and chromium 1.4E-02µg/m³ (5%). The particle mode was more towards the smaller particle size bin. These particles have atmospheric radiation forcing and health implications. We detected toxic heavy metals such as Cd, Cr, Pb and Hg. These metal leads to various health complications as they do not have a safe threshold. The study suggests a comprehensive health risk assessment for workers exposed to emissions from charcoal burning activities to develop the best risk management strategies
In order to assess compositional changes within the atmosphere it is crucial to measure concentrations of atmospheric trace gas species, which include the criteria pollutants sulphur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3). Measurement of these species with passive samplers is a generally acknowledged and frequently utilised method, which offers a cost-efficient sampling method to monitor these atmospheric species, especially, in data-scarce regions with logistical restraints. However, the performance of these passive samplers must be evaluated regularly, which include comparison to measurements conducted with active in situ samplers that are frequently quality checked and calibrated. In this manner, correction- or scaling factors are determined, which improves the accuracy and precision of passive samplers. Therefore, the aim of this study was to reevaluate passive samplers used to measure SO2, NO2 and O3 in relation to active in situ measurements of these species conducted at the Welgegund atmospheric monitoring station for approximately six years. Scaling factors of 0.9, 1.7, and 1.4 were determined for SO2, NO2, and O3, respectively, measured with passive samplers in relation to active measurements. Concentrations of these species determined with the type of passive samplers used in this study should be multiplied by these factors. These newly derived scaling factors were in the same range as previously determined correction factors. However, statistical analysis revealed that these newly determined scaling factors should be used in future studies utilising these passive samplers.
Road transportation is one of the anthropogenic sources of greenhouse gases (GHGs) and other air pollutants in Kenya, which have a serious negative impact on human health. The fact that traffic emissions happen directly at ground level in crowded urban areas and expose millions of people to dangerous pollutants like particulate matter (PM₂.₅), nitrogen oxides (NOₓ), volatile organic compounds (VOCs) among others, at concentrations significantly higher than those from industrial or natural sources makes them a more serious concern than many other emission sources. For the purpose of developing and implementing relevant policies and technology for adequate mitigation measures, an emission inventory needs to be created. The aim of the current study is to estimate the vehicular emissions from different vehicle categories using Thika Superhighway as a case study. The correlation between vehicle population, emission factors, and vehicle kilometer travelled and the levels of emissions were analyzed by use of qualitative and quantitative methods. The bottom-up approach method was used in this study. A total of 398 vehicles were sampled, which included two wheelers, three wheelers, cars and SUVs, Buses, light motor vehicle (passengers), light motor vehicles (goods) and heavy-duty vehicles (HMV). This study reported that the total vehicular emissions of NOX, CO, NMVOC, NH3, PM10, PM2.5, black carbon (BC) and organic carbon (OC) are 1,971.501, 2,232.053, 293.514, 19.543, 80.080, 80.080, 45,437.969, 1,772.328 t/year, respectively. From the study, buses were the highest contributors of NOX, PM10, PM2.5 and BC emissions, whereas two-wheelers accounted for the majority of CO and NMVOC emissions. LMV passenger (diesel) accounted for the majority of NH3 and OC emissions. Implementation of car-free days, use of hybrid and electric vehicles and introduction of policies that aim at eliminating unroadworthy automobiles are some of the policies which are recommended to minimize vehicular emissions in Nairobi County.
Atmospheric chemical composition is strongly influenced by natural and anthropogenic emission sources, which may vary with season. In this study, we investigated the trends in the impact of the West African Monsoon (WAM) on the variability of sodium (Na+), potassium (K+), and chloride (Cl−) ions in rainfall over the humid savanna of Lamto in Côte d’Ivoire. Over the 22 years (1994-2015) of the study period, a combination of in-situ rainfall measurements and satellite-based Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) precipitation data was used to understand the rainfall patterns associated with the WAM on the concentrations of these ions. Non-parametric statistical analyses were also performed. Results revealed a significant increasing trend in all three ion concentrations at the event scale, suggesting that in addition to the natural sources such as the Atlantic Ocean, the Sahel and Saharan desert, other anthropogenic factors such as road construction and urbanisation may influence the presence of these ions in the rainwater. Moreover, the strong positive correlations between Na+ and Cl− suggest a common marine source transported by the WAM flow still predominates in Lamto. However, the increasing trend in K+, which is a good tracer of biomass combustion, highlights that Lamto is also influenced by local surrounding anthropogenic sources such as biomass burning. An improved assessment of the impact of these local sources will be needed for efficient mitigation strategies in the area.
