Abstract: Volatile Organic Compounds (VOCs) impacts negatively on human health and the environment globally. Information on transport induced VOCs emission from urban roads is scanty. This study therefore determined the ambient concentration of VOCs and examined its spatial and temporal variations along urban roads in Ilorin, Nigeria. Multi-stage sampling techniques were used to select sites for emission measurement. Multi-rae plus was used to determine the concentration of VOCs at 0, 250 and 500 meters from selected road junctions in the morning (0730 – 0930 Nigerian Local Standard Time, LST), afternoon (1130 – 1400 LST) and evening (1430 – 1800 LST) of each day of the week of survey at the seven selected road junctions. A total of 441 air samples were taken and analysed in situ. Measured real time concentrations of VOCs were analyzed using descriptive statistics and Analysis of Variance. The result showed that the overall concentration of VOCs emissions averaged 1.600 ±1.600 ppm. Mean concentrations of VOCs varied as 1.494 ±1.714 ppm, 1.101 ±1.101 ppm and 1.005 ±1.417 ppm, at 0, 250 and 500 meters, respectively from the road junctions. The mean concentration of Volatile Organic Compound in the morning (0.957 ± 0.899ppm), afternoon (0.670 ±0.762ppm) and evening (1.973 ±2.251ppm) thus reveal ‘peaks’ and ‘off-peaks’ of traffic. The highest concentration (1.588ppm) was recorded at the Post office junction. Significant spatial variations existed in the mean concentration of VOCs across the various junctions F (6.434) p<0.05). The study associated variations in VOCs emission to traffic flow in the study area, and concluded that VOCs emission can be reduced if traffic flows are controlled.
Key words: Emissions, Off peak, Peaks of traffic, Spatial variations, Peaks of traffic, Off peak, Spatial variations