An Assessment of the Ambient Air Quality around Major Road Intersections within Warri Metropolis

Abstract

An evaluation of the ambient air quality of emitted gases and particles at major road junctions within Warri conurbation was carried out. The study was aimed at ascertaining if air pollution levels exceeded the acceptable limits during weekdays as well as attempt to target the root causes. Ambient air was monitored from strategic locations at eight major road junctions sparsely distributed within residential areas for in-situ measurement of NO2, SO2, CO and PM10 concentrations. Monitoring was done consecutively for a period of two weeks at four single-carriage and four dual-carriage roads to test the contributions of traffic on air quality. The averages of the minimum and the maximum daily observations over the entire sampling period ranged between 0.02452ppm and 0.05684ppm for NO2, while that of SO2 ranged between 0.00564ppm and 0.05654ppm, and that of CO ranged between 0.438ppm and 4.890ppm, whereas PM10 yielded 13.602μg/m3 as minimum and 122.124μg/m3 as maximum levels. As was expected, concentrations from all the single carriage roads were higher than those from the dual carriage roads owing to the heavy traffic congestions in single-lane roads. This study also revealed that only the NO2 values obtained around Robinson plaza and Warri main market junctions were perilously close to the specified FMENV levels for hourly exposure. This being that there were rapid oxidation of NO to NO2 from vehicular emissions. However, the presence of high levels of NO2 is synonymous to high ground level ozone production environment, consequently, a high oxidation region of free radicals which could lead to more particulate matter formation during advection.