An Assessment of Vehicular Emission in the Vicinity of Selected Markets in Owerri, Imo State, Nigeria

This study assessed pollutants concentration at selected markets in Owerri. These markets were purposively selected after careful consideration of all major markets in the study area;the selected markets were considered to be more congested during the day as a result of open assess to road junctions coupled with a high density of vehicular movement, presence of offices, residential buildings, and human activities. Five air pollutants from vehicular emissions were monitored, namely: carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), particulate matter (PM 2.5) and particulate matter (PM 10). Assessments were carried out within 3 hours per dual diurnal section using approved standard methods which were converted to a 1-hour mean for the morning and afternoon period of sampling 7-10 am and 2-5 pm. These periods are known for the peak of human and vehicular movement within the study area. Results show that the highest level of CO concentration (0.293 - 0.387 ppm) was recorded at Alaba market and is less than the permissible limit of 35 ppm given by national ambient air quality standard (NAAQS). The highest range of CO2 (1153 - 1875 ppm) was recorded from Alaba market which is higher than the ambient standard of 314 ppm. The highest level of NO2 (0.116 - 0.297 ppm) was recorded from Relief market which is also higher than the permissible limit (0.100 ppm) of NAAQS. The highest range of particulate matter of PM 2.5 and PM 10 was recorded from Relief market (0.011 - 0.029 μg/m3) and (0.065 - 0.172 μg/m3) respectively and is far lower than the permissible limit (150 μg/m3) of NAAQS and WHO (base on target 1) standards. The study, therefore, concludes that there is a significant impact of emission from vehicles in the selected markets in Owerri metropolis as result indicates a high risk of health problems in the markets due to the high level of CO2 and NO2. It, therefore, recommends that an adequate mechanism should be put in place to decongest traffic density in the city especially near markets so as to have a substantial reduction in vehicular emissions and improve the livability of the citizens.