SPATIO-TEMPORAL ANALYSIS OF CARBON MONOXIDE CONCENTRATIONS AT MAJOR ROAD JUNCTIONS IN OWERRI, NIGERIA: EVALUATING THE IMPACT OF TRAFFIC CONGESTION AND ENGINE IDLING

Abstract

Carbon monoxide (CO) poisoning is a seamless and dangerous problem in developing countries like Nigeria. Chronic exposure to low or moderate concentrations of CO cause harm to the body and can lead to death when the concentration is high. This study conducted an analysis of CO levels at three strategic high-traffic intersections within the Owerri Municipal, two high concentrated junctions; Control Junction, and Ama J.K., and one mild-concentrated junction (Rock View Junction) using a Crowcon Gasman electrochemical sensor. Data were collected simultaneously across three diurnal time blocks over a five-day period to capture peak commute fluctuations. The results reveal that CO concentrations significantly peak during morning rush (08:00–11:00) and evening peak (16:00–19:00) rush hours, driven primarily by high traffic density, prolonged engine idling, and the prevalence of poorly maintained second hand vehicles. Control Junction recorded the highest mean concentration of 54.67 ppm, with peak values reaching 58.1 ppm. Ama J.K. junction recorded a mean value of 46.33 ppm, with a peak value of 56.5 ppm, while Rockview recorded a mean value of 38.27 ppm with a peak value of 47.9 ppm The concentrations obtained significantly exceed the updated WHO (2021) safety thresholds for urban environments.