Air Quality in Relation to Vehicular Traffic-Related Gaseous Emissions in two Selected Local Government Areas in South-Western Nigeria

摘要

The aim of this study is to determine the concentration of traffic related air pollutants at major and busy road intersections in two Local Government Areas of Ibadan, Nigeria. A descriptive cross-sectional design was employed for the study. Ibadan North and North East Local Government Areas (LGAs) were purposely selected based on their high traffic density. Thirteen sampling points were randomly selected from the 18 major road intersections within the two LGAs. Levels of sulphur dioxide (SO2), nitrogen dioxide (NO2) and carbon monoxide (CO) emissions in (ppm) were measured using calibrated SO2 NO2 and COmonitor. Traffic density was estimated via manual counting using tally system. Measurements were carried out in the morning (6am-8am), afternoon (12pm-2pm) and evening (4pm-6pm) for 12 weeks and results obtained were compared with WHO guideline limit. Data were analysed using descriptive statistics, ANOVA and Pearson correlation test at 5% level of significance. The mean gaseous emissions level were CO (38.6 ± 22.2ppm), SO2 (1.0 ± 0.7ppm), NO2 (0.2 ± 0.1ppm. These values exceeded the WHO guideline limit for CO (10ppm), SO2 (0.17ppm), NO2 (0.17ppm). There was a significant difference in the mean gaseous emissions level across measurement periods of the day (8am-10am, 12pm-2pm and 4pm- 6pm) (p 0.05). There was a significant positive correlation between SO2 and traffic density (r= 0.73).Gaseous emissions exceeded the WHO guideline limit for ambient conditions at the study locations. There is need for government to institute and enforce traffic emission control and air quality management programmes in Nigeria.