Department of Physics and Computer Science
Permanent URI for this collectionhttps://dspace.njala.edu.sl/handle/20.500.144402/139
Browse
3 results
Search Results
Item Airborne Particulate Matter Concentrations at Key Transportation Stations in Freetown, Sierra Leone: Compliance With WHO Guidelines(2025-05-30) Abu, Mohamed MustaphaAir pollution, particularly from particulate matter (PM), is a significant public health risk, especially in urban environments where transportation plays a critical role. This study quantifies airborne particulate matter (PM1.0, PM2.5, and PM10) concentrations at key transportation stations (Central and Shell Bus Stations) in Freetown, Sierra Leone. Multifunctional digital air quality monitors (DM502) were used to record measurements during the rainy season in August and at peak traffic hours, spanning three daily intervals: 7:00–11:00 AM, 12:00–4:00 PM, and 5:00–9:00 PM. Our findings reveal elevated levels of particulate matter throughout the study. The average concentrations at the Central Bus Station of 15.40 µg/m³, 27.60 µg/m³, and 31.38 µg/m³ for PM1.0, PM2.5, and PM10, respectively. At Shell Bus Station, these values were notably higher, with averages of 17.71 µg/m³ for PM1.0, 30.33 µg/m³ for PM2.5, and 37.24 µg/m³ for PM10. These average concentrations notably exceed the World Health Organization (WHO) 24-hour guidelines of 15 µg/m³ for PM2.5 and 45 µg/m³ for PM10, indicating deteriorating air quality in these densely populated transit areas. Also, the mean Air Quality Indices (AQI) of PM2.5, and PM10 at Central Bus Station are 95.16 and 26.81 respectively while mean AQI of PM2.5, and PM10 at Shell Bus Station are 90.05 and 32.08 respectively. Significant variations were observed throughout the week, primarily influenced by daily traffic patterns and local activities. Peak PM2.5 levels reached 62.33 µg/m³ at Central Bus Station and 74.67 µg/m³ at Shell Bus Station on Tuesdays. Our analysis underscores the urgent need for improved air quality management strategies in Freetown to mitigate health risks associated with elevated airborne particulate levels. In conclusion, this study serves as a pivotal contribution to understanding air quality dynamics in Freetown's urban transit environment, providing essential data for stakeholders to address public health concerns linked to air pollution. Recommendations include implementing stricter vehicle emissions regulations, enhancing public transportation options, and promoting community awareness initiatives surrounding air quality. These measures are critical in fostering a healthier urban environment for residents and commuters alike.Item Evaluation of Radon-222 concentration and its associated risks in groundwater sources of communities around selected mining sites in Sierra Leone(University of Biskra, 2026-04-09) Abu, Mohamed MustaphaRadon-222 in groundwater poses significant health risks through ingestion and inhalation, being the second leading cause of lung cancer deaths in the U.S., with 21,000 fatalities annually. This study evaluated radon-222 levels and associated risks in groundwater near mining sites in Sierra Leone during the rainy season. Fifteen samples from each site – Koidu, Yengema and Marampa, were analyzed using a calibrated DURRIDGE RAD-7 detector. Risks were calculated for infants, children and adults, including annual effective doses, Excess lifetime cancer risks and Lung Cancer Cases per million people per year. The results showed that Radon-222 concentrations in the groundwater samples ranged from 5.07 to 41.63 Bq/l with an average value of 19.10 Bq/l. The total annual effective doses varied from 65.53 to 590.49 (μSv/y), highest in infants. Excess lifetime cancer risks ranged from 0.0002 to 0.0021, with infants at the greatest risk. Lung cancer incidence was approximately 0.0009 per million people per year. Importantly, all samples remained below WHO and EU limits of 100 Bq/l, indicating compliance with international safety guidelines and no immediate health risk. However, 87.5% of samples exceeded USEPA's more stringent maximum contaminant level of 11.1 Bq/l. This discrepancy reflects differing regulatory philosophies : USEPA's precautionary approach versus WHO/EU's risk-based thresholds. While the water meets international standards for safe consumption, the exceedance of USEPA standards suggests potential long-term health concerns warranting continued monitoring, particularly for vulnerable populations such as infants and children. Simple, low-cost mitigation measures such as aeration, storage (allowing radon to decay/escape) and ventilation during water use are recommended where concentrations approach upper limits. Highlights 1. This study evaluated 222Rn levels and associated risks in groundwater near mining sites in Sierra Leone during the rainy season. 2. Fifteen samples from each site – Koidu, Yengema and Marampa, were analyzed using a calibrated DURRIDGE RAD-7 detector. 3. Risks were calculated for infants, children and adults, including annual effective doses, Excess lifetime cancer risks and Lung Cancer Cases per million people per year. 4. Calculations reveal that the total annual effective doses varied from 65.53 to 590.49 (µSv/y), highest in infants. 5. Elevated 222Rn levels indicate potential long-term health risks for inhabitants, especially infants and children.Item Assessment of noise pollution levels in nightclubs in Waterloo Sierra Leone and implications for public health(Springer, 2026-06-28) Abu, Mohamed MustaphaNoise pollution is regarded the third most hazardous form of pollution, following air and water pollution. Nightclubs are significant sources of elevated noise levels that pose health risks to employees, patrons, and nearby residents. Despite these concerns, there is limited data on noise levels within Sierra Leone’s nightlife venues. The aim of this study was to precisely measure and analyze noise pollution levels in five popular nightclubs in Waterloo, Sierra Leone, and evaluate their compliance with the World Health Organization’s limit. Using a calibrated DSM8930 sound level meter set to A-weighting and slow response, maxima and minima noise levels were systematically recorded at approximately 1.5 m above ground level during peak hours (9:00 PM to 12:00 AM) over a period of five weekends (29th November, 2024 – 29th December, 2024). Multiple readings were taken at five-minute intervals, at the center and four corners in each nightclub, with data processed via descriptive statistics in Microsoft Excel 2010 to determine mean, maximum, and minimum noise levels The findings revealed that measured maxima and minima noise levels, L MAX. and L MIN. , ranged between 88.0 – 90.4 dBA and 66.0 – 88.4 dBA, respectively, while the mean noise levels ranged from 80.99 – 87.79 dBA across the venues. Specifically, the highest and lowest mean noise levels of 87.79 dBA and 80.99 dBA were observed in Club D and Club B, respectively. Mean L Aeq varied from 65.42 to 72.23 dBA, below the WHO’s recommended limit of 75 dBA. Nightclubs in Waterloo emitted mean L Aeq that complied with the WHO limit, underscoring no immediate health damange. However, there is an urgent need for the Sierra Leone Environmental Protection Agency to develop and enforce noise regulations – ensuring that the requirements for the approval of nightclubs operation include adherence to noise regulations and availabity of noise control measures, and the implementation of routine monitoring to safeguard public health and enhance community well-being. Addressing these issues is critical to prevent adverse health outcomes and preserve community well-being.