Assessment of vehicular emission contributions to ambient air quality along high and low density traffic routes in Lagos and Ile-Ife, southwestern Nigeria.
No Thumbnail Available
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Chemistry, Faculty of Science. Obafemi Awolowo University.
Abstract
The study characterized air emissions from vehicles in Lagos and Ile-Ife, determined theground-level concentrations of associated pollutants along with the ambient air quality levels of selected air pollutants and evaluated the vehicular emissions using the results obtained above. These were with a view to assessing the vehicular emission contributions to ambient air quality along low- and high-density routes in Ile-Ife and Lagos. Four sampling points were established during dry and wet season periods over an
averaging period of 24-hour, while traffic count, meteorology, and ambient measurements were carried out simultaneously at each of the sampling points. The vehicle emission measurement which is one of the inputs for predicting ground level concentrations using the BREEZE ROAD Model was carried out using Infra-Red gas analysers for CO, NO2, and SO2 concentrations and handheld aerosol real-time particulate matter (PM2.5) sampler for PM2.5 concentration. Ambient PM2.5 concentrations were measured using Air metric particulate matter sampler, while ambient gaseous concentrations of CO, NO2, SO2, O3, and volatile organic compounds (VOC) were measured using CO data logger, Ogawa sampler, and 3 M air monitor badge. The samples collected using the Ogawa sampler and 3 M air monitor badge were analysed using Gas Chromatography Flame Ionization Detector. The measured ambient mean PM2.5 concentration in Lagos was 152.58± 61.65 µg/m3 while that of Ile-Ife was 93.13±2.24 µg/m3. The measured concentrations of NO2 in Lagos ranged from 21.98 to 64.95 µg/m3and that for Ile-Ife ranged from 10.00 to 55.04 µg/m3. Sulphur dioxide concentration ranged from 20.56 to 58.09 µg/m3 in Lagos and 16.35 to 60.69 µg/m3 in Ile Ife. Carbon monoxide concentrations in Ile-Ife sampling points ranged from 1,030.68 to 3,000.42 µg/m3 while that of Lagos sampling points ranged from 1,030.68 to 3,664.64 µg/m3.Comparative high average level (40.02± 8.5 µg/m3) of VOC was recorded in Lagos than Ile-Ife with an average value of 17.33± 5.46 µg/m3. However, all ambient pollutant values were below Federal Ministry of Environment (FMEnv) and World Health Organization (WHO) limits except PM2.5 and SO2. The predicted mean ground level vehicular concentrations of PM2.5, NO2, SO2, and CO for Lagos were 117.00 ± 25.46, 33.87 ± 5.32, 16.78 ± 13 and 1885.7 ± 565.69 µg/m3respectively while that of Ile-Ife were 86.50 ± 3.54, 13.17 ± 7.98, 15.61 ± 10.97 and 1028.60 ± 969.73 µg/m3respectively. Generally, the average percentile contribution of major vehicle criteria pollutants on the airshed along low and high-density traffic routes were 31 and 42% respectively. The study concluded that the pollutant concentration values obtained, apart from those of PM2.5 and SO2 which were below FMEnv and WHO limits, could cause adverse health by those having regular impacts of the parameters investigated.
Description
xviii, 212p.
Keywords
Citation
Joshua, O.H.(2021) Assessment of vehicular emission contributions to ambient air quality along high and low density traffic routes in Lagos and Ile-Ife, southwestern Nigeria. Obafemi Awolowo University.