Real-Time Monitoring of Particulate Matter (PM2.5 and PM10) in Douala, Cameroon: Spatiotemporal Variations and Associated Health Risks

Abstract

Ambient particulate matter (PM) pollution remains a critical global environmental and public health challenge, particularly in rapidly urbanizing regions of developing countries. Exposure to PM pollution poses significant health risks, yet fine-scale temporal variations in PM_2.5 and PM₁₀ concentrations are often overlooked. This study investigates the spatiotemporal dynamics and associated health risks of PM pollution in Douala, Cameroon, from April to November 2023. Using a Temtop M2000 monitor at commercial, residential, and suburban sites, hourly concentrations of PM_2.5 and PM₁₀ were measured. The analysis employed spatiotemporal variation assessments, PM_2.5/PM₁₀ ratios, and exceedance factor (EF) techniques. Results revealed that PM concentrations consistently exceeded WHO guidelines, with hourly levels ranging from 2.0 to 120 µg/m³ for PM_2.5 and 3.3 to 190 µg/m³ for PM₁₀. Distinct diurnal, weekly, and monthly patterns were observed, with pronounced peaks during morning (7:00–9:00) and evening (17:00–21:00) rush hours, reflecting the influence of traffic emissions (TE) and human activities. The mean PM_2.5/PM₁₀ ratio of 0.62 indicated a dominance of fine particulates linked to anthropogenic sources such as TE, industrial activities, and biomass burning. Relative risk assessments revealed an average risk of 1.006 (95% CI: 0.99804–1.0147) for all-cause mortality due to PM_2.5 exposure, highlighting significant health risks for vulnerable populations, including children, the elderly, and outdoor workers. Critical time windows of elevated PM exposure were identified, particularly during rush hours, weekends, and the rainy season, underscoring the need for targeted air quality management strategies. Integrating advanced analytical techniques, including positive matrix factorization (PMF) and meteorological data, this research provides a high-resolution understanding of PM pollution in a tropical urban environment, offering actionable insights for mitigating air pollution and protecting public health.