Abstract

Levels of vehicular emission pollutants (CO, NO₂, and PM_2.5) 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: PM_2.5 (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 PM_2.5 (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 PM_2.5, 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 PM_2.5) 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.

摘要

在尼日利亚拉各斯的一条主要高速公路上使用不同的最先进的分析技术测量了车辆排放污染物（CO、NO ₂和 PM _2.5 ）的水平，而 BREEZE ROAD 扩散模型用于预测车辆对使用交通计数、车辆排放因子和气象数据、建模受体、交通和道路状况的空气流域。在研究路线沿线的 5 个采样点进行交通计数、气象和实际环境测量， 每天 12 小时，每个雨季和旱季连续 3 次。将色散模型结果与实际环境测量结果进行比较。预测平均值如下： PM _2.5 (112  µg/m ³; 76.4  µg/m ³ )、NO ₂ (52.68 µg/m ³ ; 37.63 µg/m ³ )、CO (2,141.3 µg/m ³ ; 2,834.3 µg/m ³ )，而测量水平显示 PM _2.5 (208.49 µg/m ³ ) ; 167.05 µg/m ³ )、NO ₂ (67.10 µg/m ³ ; 50.16 µg/m ³ ) 和 CO (6,489.47 µg/m ³ ; 10,115.88 µg/m ³ ) 沿研究路线分别在旱季和雨季. 模型和实际测量结果被用作基于小时分析和季节变化的百分位数分析的输入。一般来说，测得的 PM_2.5，由于其他来源的贡献，所有采样站的CO和NO ₂值均高于模型值。此外，由于降水量减少和风速较大，旱季测量的污染物值高于雨季。某些地点的污染物浓度低于其可容忍限度（PM _{2.5除外）。}然而，这些有害污染物在空气流域中的积累会改变气候条件，对环境造成威胁，并带来健康不良的伴随者。