Seasonal Monitoring of Criteria Air Pollutants and Noise Levels across Six Selected Housing Estates in Ogun State, Nigeria

ABSTRACT; Levels of criteria air pollutants (CAP) between Dry and Wet seasons vary, this could be indicated when assessed and compared with the thresholds. Their seasonal variations were assessed in six chosen housing estates for possible air pollution on the inhabitants, whose intention is to live in an area that is conducive. Six CAP and noise levels were assessed across the selected housing estates in Ogun State to evaluate their levels for two dry and wet seasons. The CAP (CO2, CO, NO2, H2S and SO2, volatile organic compound (VOC)) and noise levels were quantified using calibrated handheld equipment; hung 1.5 m above ground. Sampling was done 8hrs/ day, once a week for three months in each dry (starting from June) and wet (starting from November) season. Obtained data were subjected to descriptiveand inferential statistics at p 0.05 level of statistical significance. There were indications that levels of CO2and CO in the dry seasons were 3-folds the wet seasons while NO2in 10-folds, levels of both H2S and SO2were below the detection limits in the wet seasons but exceeded the limits in dry seasons. Levels of VOC and Noise were not different in the two seasons. Order of percentage influence of the CAP was CO2> SO2> SPM > CO > VOC across the sampling seasons: CO2> CO > VOC > NO2 > SPM in the wet season but SO2> SPM > VOC > CO2> CO in the dry season from Linear regression equation. Season was observed to dictate CAP unlike noise levels.

摘要：标准空气污染物（Criteria Air Pollutants，CAP）在旱季与雨季的浓度水平存在差异，该差异可通过与限值对比评估得出。本研究选取尼日利亚奥贡州6个选定住宅区，评估CAP的季节变化特征，以分析其对居民的潜在空气污染影响——居民往往期望居住在环境宜居的区域。
研究针对上述6个住宅区，测定了6项CAP及噪声水平，以评估旱季与雨季的污染物与噪声水平。本次测定的CAP包括二氧化碳（CO₂）、一氧化碳（CO）、二氧化氮（NO₂）、硫化氢（H₂S）、二氧化硫（SO₂）以及挥发性有机物（Volatile Organic Compound，VOC），同时测定噪声水平；所有测量均采用校准后的手持式设备，设备悬挂于地面上方1.5米处。
采样工作于每个季开展：旱季（始于6月）与雨季（始于11月）各持续3个月，每日采样8小时，每周采样1次。采集得到的数据采用描述性与推断性统计方法进行分析，显著性水平设定为p=0.05。
分析结果显示，旱季的二氧化碳与一氧化碳浓度分别为雨季的3倍，二氧化氮浓度则为雨季的10倍；硫化氢与二氧化硫在雨季的浓度均低于检出限，但在旱季则超出限值。而挥发性有机物与噪声水平在两个季节间无显著差异。
基于线性回归方程的分析结果显示，CAP的百分比影响权重在全采样周期内排序为：CO₂＞SO₂＞SPM＞CO＞VOC；其中雨季的权重排序为CO₂＞CO＞VOC＞NO₂＞SPM，旱季则为SO₂＞SPM＞VOC＞CO₂＞CO。与噪声水平不同，季节是影响CAP浓度的决定性因素。