TITLE:
High-Temporal-Resolution Characterization of PM2.5 and PM10 in Contrasting Urban Environments of Korhogo, Northern Côte d’Ivoire
AUTHORS:
Aka Jacques Adon, Sekou Keita, Julien Bahino, Gnamidjo Soro, Sylvain Gnamien, Doumbia Madina, Alima Dajuma, Marcellin Adon, Siélé Silué, Véronique Yoboué
KEYWORDS:
PM2.5, PM10, Diurnal Variability, Low-Cost Sensors, Urban Air Pollution, Korhogo, Côte d’Ivoire
JOURNAL NAME:
Open Journal of Air Pollution,
Vol.15 No.4,
October
30,
2026
ABSTRACT: Particulate matter pollution remains poorly characterized in secondary cities of West Africa, particularly in northern Côte d’Ivoire. This study investigated PM2.5 and PM10 concentrations and their diurnal variability during sequential dry-season monitoring at three contrasting urban sites in Korhogo: UPGC, Kassirimé, and Petit-Paris. Measurements were performed using a SENSIT RAMP monitor at 15-s resolution and processed following quality-control procedures. Measurements from the two particulate matter sensing channels were averaged and aggregated to hourly concentrations. A field calibration model incorporating relative humidity was then applied to PM2.5, whereas PM10 was retained as an uncorrected sensor-derived concentration estimate because no independent reference-based PM10 calibration was available. Daily means were retained when at least 75% hourly coverage was available. Mean daily corrected PM2.5 concentrations were 31.0 µg∙m−3 at UPGC, 25.2 µg∙m−3 at Kassirimé, and 24.7 µg∙m−3 at Petit-Paris, while corresponding uncorrected PM10 concentrations were 28.1, 20.0, and 20.4 µg∙m−3, respectively. The UPGC deployment exhibited both the highest concentrations and the greatest day-to-day variability, although differences in daily means between deployments were not statistically significant (Kruskal-Wallis, p = 0.056). During all three deployments, PM2.5 and PM10 displayed pronounced bimodal diurnal patterns, with morning and evening peaks separated by lower midday concentrations. Weekday-weekend contrasts differed among the three site-period deployments: Kassirimé showed markedly higher peak concentrations on weekdays, whereas Petit-Paris generally exhibited higher peaks during weekends; however, weekday-weekend differences in daily mean concentrations were not statistically significant, and the weekend profiles rested on a few days. The PM2.5/PM10 ratio, calculated from paired uncorrected sensor-derived estimates, was highest at Petit-Paris (0.85), intermediate at UPGC (0.81), and lowest at Kassirimé (0.79); it is interpreted only as a relative sensor-derived metric and not as a direct particle-size measurement. Overall, the results highlight substantial dry-season particulate pollution in Korhogo and demonstrate the value of high-temporal-resolution monitoring for characterizing short-term pollution dynamics in contrasting urban environments.