Assessment of particulate matter (PM10, PM5, PM2.5, and PM1) concentrations at significant intersections in Douala-Cameroon city using low-cost sensors

Abstract

The uneven PM exposure in urban areas poses problems and gives rise to models of detrimental health impacts. Low-cost sensors like the OC-300 Laser Gas and Dust Particle Detector allow for the continuous and simultaneous measurement of the particle concentration at different places within the study area. Measurements of ambient PM were conducted from January to March 2023 in order to assess the temporal and geographical variability of PM as well as the relative importance of traffic in relation to the concentration of outdoor PM in Douala. The analyses were performed using statistical methods. The study found that, on an hourly and daily average, PM₁, PM_2.5, PM₅, and PM₁₀ concentrations, in particular, range 24–127 µg/m³, 44–210 µg/m³, 48–225 µg/m³, and 50–240 µg/m³, respectively. Diffuse concentrations are found at locations with significant concentrations of pollutants, according to spatial mapping (Q3, Carrefour Ndokoti; Q5, Carrefour PK14). PM₁₀ and PM_2.5 particle air quality indices fall into the bad and extremely poor categories. For Q3 and Q5, the PM_2.5 air quality index is 660.86% and 580.46%, respectively. In contrast, Q3 and Q5 PM₁₀ levels are 264.97% and 231.37%, respectively. While Q5’s high concentrations are caused by the phenomenon of re-suspension brought on by the presence of unpaved roads, Q3’s high concentrations are the result of the area’s significant traffic. According to the study, the levels of PM_2.5 and PM₁₀ are five and eleven times higher, respectively, than the most recent WHO limits for daily exposure. This study provides important information on the pollution levels in Douala, which should be considered since they could be a major cause of illness in the area.