The spatial–temporal variations of fine particulate matter (PM_2.5) in Akure, a city in southwestern Nigeria, are examined based on multi-year continuous observations using low-cost PM_2.5 sensors at six different sites. The average annual concentration of PM_2.5 across these sites was measured at 41.0 µg/m³, which surpassed both the Nigerian national air quality standard and the World Health Organization air quality guideline level. PM_2.5 levels were significantly higher during the dry season (November–March), often exceeding hazardous levels (over 350 µg/m³), than during the wet season. The analyses of trends in air mass trajectories and satellite data on fire occurrences imply that the transport of dust and accumulation of PM_2.5 originating from local/regional open burning activities played crucial roles in increased PM_2.5 concentrations during the dry season. Further, site-to-site variations in the PM_2.5 levels were observed, with relatively high concentrations at less urbanized sites, likely due to high local emissions from solid fuel combustion, waste burning, and unpaved road dust. Diurnal patterns showed morning and evening peaks at less urbanized sites, accounting for an estimated 51–77% of local emissions. These results highlight the importance of local emission sources in driving spatial–temporal PM_2.5 variations within the city and the need for targeted mitigation strategies to address the significant air pollution challenges in Akure and similar regional cities in West Africa.

Air pollution, particularly fine particulate matter (PM2.5), poses a significant threat to public health, especially in rapidly urbanizing areas like Lagos State. Despite the severity of the issue, there is a lack of comprehensive data on PM2.5 levels and the Air Quality Index (AQI) in Lagos. This study leverages data from AirQo, an innovative air quality monitoring network using low-cost sensors, to provide a detailed assessment of PM2.5 concentrations and AQI across eight locations in Lagos State, Nigeria. This approach offers real-time, continuous monitoring, filling a critical data gap in the region's air quality management efforts. This study uses AirQo data to assess the concentration levels and spatial distribution of PM2.5 and AQI across the selected eight locations. Data on PM2.5 concentrations were obtained from AirQo sensors deployed across the eight strategic locations in Lagos. The spatial distribution of PM2.5 levels and AQI were analyzed, and the results were compared with national and international air quality standards. The findings revealed that PM2.5 levels (minimum – 6.28 µg/m3 (Ikeja) and maximum - 204.68 µg/m3 (Banana Island) in many areas of Lagos exceed annual WHO and national air quality guidelines, indicating significant health risks. The spatial analysis identified pollution hotspots, particularly in densely populated and industrial regions. The data suggested vehicular emissions and industrial activities as major contributors to high PM2.5 levels. This study underscores the severe air quality issues in Lagos State, emphasizing the need for immediate and targeted interventions to mitigate PM2.5 pollution. The use of AirQo sensors proved effective in providing accurate and timely data for air quality assessment. It is recommended that Lagos State implements stricter emission controls, promotes cleaner technologies, and enhances public transportation systems to reduce traffic-related pollution. Additionally, expanding the air quality monitoring network and incorporating more environmental data will provide a more comprehensive understanding of air pollution impacts, thereby facilitating better policy and public health decisions.

This study presents a comparative analysis of indoor air quality (IAQ) across health centers in Arakale, Iju, Owode, FECA, and Oba Ile, Ondo State, Nigeria. Particle count data were analyzed to identify common trends, similarities, and differences in IAQ parameters, with the aim of informing targeted interventions for improving indoor air quality in healthcare settings. The findings reveal consistent positive skewness in particle count distributions, indicating occasional spikes in pollution levels amidst generally lower concentrations. Fine particles in the size range of PC 2.5 were consistently dominant across all locations, emphasizing their significance in IAQ assessment. Similar variability in particle count data suggests comparable levels of fluctuations in IAQ among the health centers. However, variations in PCA patterns highlight unique factors influencing IAQ in specific locations, such as combustion sources and control strategies. Targeted interventions, including enhancing ventilation systems, controlling indoor pollution sources, and promoting smoking cessation programs, are proposed to mitigate health risks associated with indoor air pollution exposure. Ongoing monitoring and collaboration with environmental experts are crucial for assessing IAQ trends and implementing evidence-based interventions to safeguard the health of patients, staff, and visitors in healthcare facilities.

Particulate matter with aerodynamic diameters smaller than 2.5 µm, PM_2.5, is a problem for inhabitants globally. To address this problem, there is a need to know the amount of PM_2.5 present in the atmosphere. The quantification of PM_2.5 will help to determine the type of remedies for air quality. One of the employed quantification methods is the use of low-cost sensors, which are easy to use, have high temporal resolution, and are small to handle. In this study, we applied low-cost optical sensors to determine PM_2.5 during the dry (Harmattan) season at two sites in Akure, Ondo State, Nigeria. The results showed that PM_2.5 at one site (Site B) ranged between 14.4 and 590.4 µg/m³, whereas that at the other site (Site C) ranged between 14.5 and 737.2 µg/m³. The mean values (75.7 and 87.5 µg/m³ at Sites B and C, respectively) were significantly beyond the standard limits of World Health Organization and National Environmental Standards and Regulations Enforcement Agency in Nigeria. High daily average PM_2.5 concentrations were observed when the air masses coming from the northeast. Shorter timescale peaks within a few hours were frequently observed, especially at Site C during the daytime, attributable to the local emissions of PM_2.5 due to combustion activities. Higher-density multi-point observations are highly recommended to understand the sources, behaviors, and health effects of PM_2.5 in regional cities in South West Africa.

Human health is at risk when particulate matter levels reach a certain threshold, and determining these levels is crucial for mitigating environmental pollution. Since there is a lack of data in this field of study, it is anticipated that this work will provide stakeholders with data. On the basis of this supposition, an Airly sensor was used to assess the air quality at a location in Mafoluku, Lagos, Nigeria. Following the manufacturer's instructions, the installation was done at a height of 1.8 meters above the ground. Outdoor PM1, PM2.5, PM10, PM ratios, toxicity potentials (T/P), climatic factors, and their correlations were measured during a two-month period. The findings indicate that the levels of PM10, PM2.5, and PM1 were 36.12 μg/m3 (equivalent to 80.7% of the WHO annual limit), 34.83 μg/m3 (equivalent to 232.23% of the WHO annual limit), and 34.39 μg/m3 (no limit for the calculation), respectively. The corresponding average ratios were 0.98, 0.95, and 0.93. The majority of T/P values were greater than 1, which suggests that there are health risks to the area's most vulnerable residents. Winds from the southwestern desert influenced the air mass, and WHO limits are often exceeded. The study suggests stakeholders focus on problem reduction to mitigate air pollution risks.