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.

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.

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.

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 paper presents the first-of-its-kind quantification of air quality benefits from a waste collection intervention in South Africa, using South African-based emission factors and dispersion modelling. Air pollutants are released from the open burning of unrecycled municipal solid waste (MSW). This study focused on waste collection in the Zamdela township, Sasolburg, within the Vaal Triangle Airshed Priority Area (VTAPA), using emission factors published by Wang et al. (2023) and waste collection quantities over 3 years from 2018 to 2020. Emissions from the waste skips were simulated in the CALPUFF dispersion model to assess impacts on air quality within the ambient environment. Several dispersion modelling scenarios based on different receptor configurations (i.e. ring, regular gridded and discrete) were investigated. From the total mass of waste collected over the period (13,798 tons), average emission rates of 3.27 tons of SO2, 25.04 tons of PM10, and 23.66 tons of PM2.5 were calculated using the applied emission factors. The ring receptor configuration generally predicted higher ambient concentrations for all pollutants over the various averaging periods. This study highlights the benefits of the waste collection offsetting intervention for ambient air quality.

Poor air quality in urban settings poses a significant global challenge with adverse environmental-health effects. In Zimbabwe, a critical knowledge gap exists regarding specific characteristics and seasonal variability of ambient air pollution in low-income, densely populated settlements, with existing studies often relying on indirect assessments. This stems from the lack of a national monitoring network, largely due to the prohibitive cost of research-grade instruments. The purpose of the was to demonstrate a viable approach to generate localized data needed to fill the national data gap through the deployment of a low-cost sensor in a representative densely populated urban settlement of Cold Comfort, Harare over a 12-month period. The deployed sensor measured particulate matter concentrations (PM2.5 and PM10) at 5-minute temporal resolution, which were then aggregated to hourly averages and analysed using open-air in R statistical packages. Results show that ambient particulate matter concentrations were elevated during winter, with annual means of 34.1 µg/m³ for PM2.5 and 58.1 µg/m³ for PM10. These levels significantly exceeded the WHO annual mean guidelines of 5 µg/m³ and 25 µg/m³ for both PM25 and PM10, highlighting local air quality concerns. A HYSPLIT trajectory analysis of a peak winter pollution event suggested that the high concentrations were a combination of long-range pollutant transport and enrichment from local emission sources. The low-cost sensor performance was evaluated against gravimetric measurements using Mean Absolute Error, Root Mean Square Error, and coefficient of determination. The low-cost sensor consistently under-estimated PM10 concentrations, showing a Mean Absolute Error of 14.2 µg/m³, Root Mean Square Error of 19.7 µg/m³, and an R² of 0.47. Despite accuracy limitations, the low-cost sensor provided a useful overview of pollution levels. As the first long-term, campaign-based study of its kind in Zimbabwe, these findings are vital for informing air quality management policy and developing targeted interventions.

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.

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.

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.