| Abstrakt: |
Levels of vehicular emission pollutants (CO, NO2, and PM2.5) were measured along a major highway in Lagos, Nigeria using different state-of-the-art analytical techniques, while BREEZE ROAD dispersion model was used to predict the vehicular contributions to airshed using traffic count, vehicular emission factor, and meteorological data, modelling receptor, traffic and road condition. Traffic count, meteorology and actual ambient measurements were carried out at 5 sampling sites along the studied route for 12 h per day for three consecutive times per rainy and dry season. Dispersion model results were compared with that of actual ambient measurement. Predicted average values were as follow: PM2.5 (112 µg/m3; 76.4 µg/m3), NO2 (52.68 µg/m3; 37.63 µg/m3), CO (2,141.3 µg/m3; 2,834.3 µg/m3), while measured levels showed PM2.5 (208.49 µg/m3; 167.05 µg/m3), NO2 (67.10 µg/m3; 50.16 µg/m3), and CO (6,489.47 µg/m3; 10,115.88 µg/m3) along the studied route during the dry and wet seasons respectively. The model and actual measurement results were used as an input for the percentile analysis based on hourly analysis and seasonal variation. In general, the measured PM2.5, CO and NO2 values were higher than the model values at all the sampling stations due to contributions from other sources. Also, higher values were recorded for the measured pollutants during dry season than the wet season due to lower precipitation and greater wind speed. Concentrations of the pollutants were below their tolerable limits (except PM2.5) at some locations. However, accumulation of these harmful pollutants in the airshed will alter climatic conditions, pose threat to the environment with their ill-health attendants. [ABSTRACT FROM AUTHOR] |
