Prince Junior Asilevi

Nitrogen dioxide (NO ₂ ) is a major urban air pollutant, yet assessment of population exposure remains challenging across West Africa due to lack of uncoordinated sparse monitoring infrastructure. We present the City-Level Nitrogen Dioxide Exposure (CLeNE) platform, an interactive exposure intelligence system that integrates Sentinel-5P TROPOMI NO ₂ observations, population data, and city boundaries to quantify and visualize urban exposure burden. Population-weighted exposure (PWE) and a Normalized Population-Weighted Exposure Index (NPWEI) were developed to enable standardized comparison among cities. Analysis of 2019–2024 observations identified persistent exposure hotspots along the Gulf of Guinea corridor, particularly in southern Nigeria, Ghana, Benin, and Côte d’Ivoire. Nigeria recorded the highest annual country-level PWE (1.59 × 10 ¹⁵ molecules cm⁻ ² ), while Abuja had the highest relative exposure ranking among capital cities (NPWEI = 100). The platform transforms satellite-derived observations into accessible exposure intelligence products, providing a scalable framework for sustainable urban planning, air-quality assessment, hotspot identification, and environmental decision support in data-sparse regions.

Biomass burning is a major source of air pollution across West Africa, yet its contribution to nitrogen dioxide variability is not well understood. Here we use satellite observations from 2019 to 2024 to examine relationships between fire activity and tropospheric nitrogen dioxide across six West African countries. Fire activity shows strong seasonal concentration, while nitrogen dioxide exhibits more moderate variability influenced by both combustion and persistent urban emissions. A strong statistical relationship between fire activity and nitrogen dioxide, with correlation coefficients ranging from 0.68 to 0.97, indicates that seasonal burning contributes to episodic pollution events. Analysis of vertical atmospheric motion at 850 hectopascals shows that dry-season subsidence suppresses dispersion and favors pollutant accumulation. The results demonstrate how emissions and meteorology interact to drive regional pollution variability and identify periods of elevated exposure potential. Improved monitoring is important for air quality management in the region.

Air pollution poses an increasing public health risk in many African cities, where systematic monitoring is limited by the high cost of reference-grade instrumentation. Satellite-based sensors such as TROPOMI on Sentinel-5P provide global coverage of atmospheric pollutants, including nitrogen dioxide (NO2), but their limited vertical resolution complicates the estimation of surface-level concentrations. Palmes diffusion tubes offer a low-cost, low-tech alternative for measuring NO2 at the ground level. Combining satellite observations with data from ground-based diffusion tubes presents a promising approach for generating regional air quality maps, particularly in resource-limited settings. This study reports on the implementation of a pilot network of Palmes tubes in Kumasi, Ghana. To ensure sustainability and scalability, a local air quality laboratory was established to prepare and analyse the tubes using locally sourced materials and equipment. Validation against tubes prepared and analysed by an accredited external laboratory demonstrated satisfactory agreement. Measurements from March 2025 revealed a wide range of NO2 concentrations, from an average of 7 µg m−3 in residential areas away from traffic and industry to peak values of 88 µg m−3 at heavily trafficked intersections – substantially exceeding the WHO 2021 guideline limits of 25 µg m−3 for 24 h exposure and 10 µg m−3 for annual mean concentrations. Averaged satellite data showed the accumulation of NO2 plumes downwind of the city, though the relationship with surface-level measurements remains complex and needs further investigation. Column-to-surface ratios in Kumasi are significantly lower than those typically observed in European cities. Using a parametrization method based on ground-based measurements and TROPOMI retrievals, we find that TROPOMI underestimates tropospheric NO2 column densities by roughly a factor of 2.5 in March 2025. This underestimation is attributed to higher aerosol loading over Ghana, which reduces retrieval sensitivity in the troposphere and increases reliance on unrepresentative a priori profiles.

Air pollution poses an increasing public health risk in many African cities, where systematic monitoring is limited by the high cost of reference-grade instrumentation. Satellite-based sensors such as TROPOMI on Sentinel-5P provide global coverage of atmospheric pollutants, including nitrogen dioxide (NO₂), but their limited vertical resolution complicates the estimation of surface-level concentrations. Palmes diffusion tubes offer a low-cost, low-tech alternative for measuring NO₂ at the ground level. Combining satellite observations with data from ground-based diffusion tubes presents a promising approach for generating regional air quality maps, particularly in resource-limited settings. This study reports on the implementation of a pilot network of Palmes tubes in Kumasi, Ghana. To ensure sustainability and scalability, a local air quality laboratory was established to prepare and analyse the tubes using locally sourced materials and equipment. Validation against tubes prepared and analysed by an accredited external laboratory demonstrated satisfactory agreement. Measurements from March 2025 revealed a wide range of NO₂ concentrations, from an average of 7 µg m^-3 in residential areas away from traffic and industry to peak values of 88 µg m^-3 at heavily trafficked intersections – substantially exceeding the WHO 2021 guideline limits of 25 µg m^-3 for 24-hour exposure and 10 µg m^-3 for annual mean concentrations. Averaged satellite data showed the accumulation of NO₂ plumes downwind of the city, though the relationship with surface-level measurements remains complex and needs further investigation. Column-to-surface ratios in Kumasi are significantly lower than those typically observed in European cities. TROPOMI underestimates the tropospheric NO₂ column densities by a factor of roughly 2.5 in March 2025, as the higher aerosol loading over Ghana reduces retrieval sensitivity in the troposphere, increasing the reliance on unrepresentative a priori profiles.

Air pollution poses an increasing public health risk in many African cities, where systematic monitoring is limited by the high cost of reference-grade instrumentation. Satellite-based sensors such as TROPOMI on Sentinel-5P provide global coverage of atmospheric pollutants, including nitrogen dioxide (NO₂), but their limited vertical resolution complicates the estimation of surface-level concentrations. Palmes diffusion tubes offer a low-cost, low-tech alternative for measuring NO₂ at the ground level. Combining satellite observations with data from ground-based diffusion tubes presents a promising approach for generating regional air quality maps, particularly in resource-limited settings. This study reports on the implementation of a pilot network of Palmes tubes in Kumasi, Ghana. To ensure sustainability and scalability, a local air quality laboratory was established to prepare and analyse the tubes using locally sourced materials and equipment. Validation against tubes prepared and analysed by an accredited external laboratory demonstrated satisfactory agreement. Measurements from March 2025 revealed a wide range of NO₂ concentrations, from an average of 7 µg m^-3 in residential areas away from traffic and industry to peak values of 88 µg m^-3 at heavily trafficked intersections – substantially exceeding the WHO 2021 guideline limits of 25 µg m^-3 for 24-hour exposure and 10 µg m^-3 for annual mean concentrations. Averaged satellite data showed the accumulation of NO₂ plumes downwind of the city, though the relationship with surface-level measurements remains complex and needs further investigation. Column-to-surface ratios in Kumasi are significantly lower than those typically observed in European cities. TROPOMI underestimates the tropospheric NO₂ column densities by a factor of roughly 2.5 in March 2025, as the higher aerosol loading over Ghana reduces retrieval sensitivity in the troposphere, increasing the reliance on unrepresentative a priori profiles.

Methane (CH₄) emissions from tropical reservoirs are sensitive to hydroclimatic and biogeochemical pressures, yet the dominant controls remain poorly quantified. Here, we combine satellite-derived chlorophyll-a (Chl-a) with a Bayesian upscaling model trained on a global CH₄–Chl-a dataset to estimate long-term (2012–2024) diffusive and ebullitive CH₄ emissions from Volta Lake in Ghana, the world’s largest artificial reservoir by surface area. Modeled emissions show substantial interannual variability and a pronounced post-2016 decline. Annual diffusive emissions ranged from 30.2 - 72.8 Gg CH₄-C yr⁻¹, ebullitive emissions from 109.1 - 211.9 Gg CH₄-C yr⁻¹, yielding combined emissions of 139.2 - 284.7 Gg CH₄-C yr⁻¹. Interannual CH₄ variability closely followed changes in lake-mean Chl-a, consistent with productivity-linked organic matter supply as a key constraint on methanogenesis. In contrast, annual associations between Chl-a (and modeled CH₄) and rainfall, evapotranspiration, or radiation were weak and not statistically significant, suggesting that hydroclimatic influence may operate primarily through seasonal watershed–lake biogeochemical coupling rather than year-to-year mean climate anomalies. These results highlight the sensitivity of Volta Lake methane emissions to long-term shifts in productivity, with implications for reservoir greenhouse gas budgets under changing hydroclimate.

Air pollution poses an increasing public health risk in many African cities, where systematic monitoring is limited by the high cost of reference-grade instrumentation. Satellite-based sensors such as TROPOMI on Sentinel-5P provide global coverage of atmospheric pollutants, including nitrogen dioxide (NO₂), but their limited vertical resolution complicates the estimation of surface-level concentrations. Palmes diffusion tubes offer a low-cost, low-tech alternative for measuring NO₂ at the ground level. Combining satellite observations with data from ground-based diffusion tubes presents a promising approach for generating regional air quality maps, particularly in resource-limited settings. This study reports on the implementation of a pilot network of Palmes tubes in Kumasi, Ghana. To ensure sustainability and scalability, a local air quality laboratory was established to prepare and analyse the tubes using locally sourced materials and equipment. Validation against tubes prepared and analysed by an accredited external laboratory demonstrated satisfactory agreement. Measurements from March 2025 revealed a wide range of NO₂ concentrations, from an average of 7 µg m^-3 in residential areas away from traffic and industry to peak values of 88 µg m^-3 at heavily trafficked intersections – substantially exceeding the WHO 2021 guideline limits of 25 µg m^-3 for 24-hour exposure and 10 µg m^-3 for annual mean concentrations. Averaged satellite data showed the accumulation of NO₂ plumes downwind of the city, though the relationship with surface-level measurements remains complex and needs further investigation. Column-to-surface ratios in Kumasi are significantly lower than those typically observed in European cities. TROPOMI underestimates the tropospheric NO₂ column densities by a factor of roughly 2.5 in March 2025, as the higher aerosol loading over Ghana reduces retrieval sensitivity in the troposphere, increasing the reliance on unrepresentative a priori profiles.

Air pollution poses an increasing public health risk in many African cities, where systematic monitoring is limited by the high cost of reference-grade instrumentation. Satellite-based sensors such as TROPOMI on Sentinel-5P provide global coverage of atmospheric pollutants, including nitrogen dioxide (NO₂), but their limited vertical resolution complicates the estimation of surface-level concentrations. Palmes diffusion tubes offer a low-cost, low-tech alternative for measuring NO₂ at the ground level. Combining satellite observations with data from ground-based diffusion tubes presents a promising approach for generating regional air quality maps, particularly in resource-limited settings. This study reports on the implementation of a pilot network of Palmes tubes in Kumasi, Ghana. To ensure sustainability and scalability, a local air quality laboratory was established to prepare and analyse the tubes using locally sourced materials and equipment. Validation against tubes prepared and analysed by an accredited external laboratory demonstrated satisfactory agreement. Measurements from March 2025 revealed a wide range of NO₂ concentrations, from an average of 7 µg m^-3 in residential areas away from traffic and industry to peak values of 88 µg m^-3 at heavily trafficked intersections – substantially exceeding the WHO 2021 guideline limits of 25 µg m^-3 for 24-hour exposure and 10 µg m^-3 for annual mean concentrations. Averaged satellite data showed the accumulation of NO₂ plumes downwind of the city, though the relationship with surface-level measurements remains complex and needs further investigation. Column-to-surface ratios in Kumasi are significantly lower than those typically observed in European cities. TROPOMI underestimates the tropospheric NO₂ column densities by a factor of roughly 2.5 in March 2025, as the higher aerosol loading over Ghana reduces retrieval sensitivity in the troposphere, increasing the reliance on unrepresentative a priori profiles.

Air pollution poses an increasing public health risk in many African cities, where systematic monitoring is limited by the high cost of reference-grade instrumentation. Satellite-based sensors such as TROPOMI on Sentinel-5P provide global coverage of atmospheric pollutants, including nitrogen dioxide (NO₂), but their limited vertical resolution complicates the estimation of surface-level concentrations. Palmes diffusion tubes offer a low-cost, low-tech alternative for measuring NO₂ at the ground level. Combining satellite observations with data from ground-based diffusion tubes presents a promising approach for generating regional air quality maps, particularly in resource-limited settings. This study reports on the implementation of a pilot network of Palmes tubes in Kumasi, Ghana. To ensure sustainability and scalability, a local air quality laboratory was established to prepare and analyse the tubes using locally sourced materials and equipment. Validation against tubes prepared and analysed by an accredited external laboratory demonstrated satisfactory agreement. Measurements from March 2025 revealed a wide range of NO₂ concentrations, from an average of 7 µg m^-3 in residential areas away from traffic and industry to peak values of 88 µg m^-3 at heavily trafficked intersections – substantially exceeding the WHO 2021 guideline limits of 25 µg m^-3 for 24-hour exposure and 10 µg m^-3 for annual mean concentrations. Averaged satellite data showed the accumulation of NO₂ plumes downwind of the city, though the relationship with surface-level measurements remains complex and needs further investigation. Column-to-surface ratios in Kumasi are significantly lower than those typically observed in European cities. TROPOMI underestimates the tropospheric NO₂ column densities by a factor of roughly 2.5 in March 2025, as the higher aerosol loading over Ghana reduces retrieval sensitivity in the troposphere, increasing the reliance on unrepresentative a priori profiles.