Model fit summary.

One of the main causes of air pollution, particularly in large cities, is vehicles due to it continued use of hydrocarbon fuels. The understanding of nonlinear interactions of vehicle parameters uncovers more realistic relationships for enhancing formulation of strategies to address vehicle-related pollution. Thus, the study aims to evaluate the interaction and quadratic effect of vehicle parameters on Hydrocarbon (HC), Carbon dioxide (CO2), Carbon monoxide (CO), and Nitrogen oxide (NOx) emissions. The SV-5Q Vehicle Exhaust Gas Analyzer was used to collect emission concentrations data from one thousand and two (1002) light-duty petrol vehicles at three (3) government-accredited vehicle inspection sites in Accra, Ghana. Pollution control devices, maintenance frequency, and vehicle age were also collected. The linear regression analysis revealed that vehicle age showed a positive linear relationship with CO emissions. Maintenance frequency, on the other hand, demonstrated a negative linear relationship with both CO and HC emissions. The interaction between vehicle age and maintenance frequency positively impacted CO and HC emissions, while the interaction between vehicle age and emission technology had a negative effect on CO. Additionally, the combined effect of frequency of maintenance and emission technology significantly reduced CO emissions but increased HC emissions. Notably, the quadratic effect of vehicle age positively influenced CO emissions. Similarly, CO, HC, and NOx emissions were positively correlated with the squared effect of emission technology. Stricter emissions standards, encouraging frequent maintenance and testing of vehicular exhaust emissions, and doing away with over-aged vehicles are recommended to control and reduce vehicular exhaust emissions.机动车持续使用烃类燃料，是空气污染（尤其是大城市空气污染）的主要诱因之一。深入解析车辆参数间的非线性交互作用，可揭示更贴合实际工况的关联规律，助力优化车辆相关污染治理策略的制定。据此，本研究旨在评估车辆参数对烃类（Hydrocarbon, HC）、二氧化碳（Carbon dioxide, CO₂）、一氧化碳（Carbon monoxide, CO）以及氮氧化物（Nitrogen oxide, NOₓ）排放的交互作用与二次效应。本研究采用SV-5Q型车辆尾气分析仪，在加纳阿克拉的3家政府认证车辆检测站点，采集了1002辆轻型汽油车的尾气排放浓度数据，同时收集了车辆污染控制装置、保养频次以及车辆使用年限等信息。线性回归分析结果显示，车辆使用年限与一氧化碳（CO）排放呈显著正线性相关；而保养频次则与一氧化碳（CO）和烃类（HC）排放均呈显著负线性相关。车辆使用年限与保养频次的交互作用对一氧化碳（CO）和烃类（HC）排放产生正向影响，而车辆使用年限与排放技术的交互作用则对一氧化碳（CO）排放产生负向影响。此外，保养频次与排放技术的联合效应可显著降低一氧化碳（CO）排放，却会提升烃类（HC）排放。值得注意的是，车辆使用年限的二次效应对一氧化碳（CO）排放产生正向影响；同理，一氧化碳（CO）、烃类（HC）与氮氧化物（NOₓ）排放与排放技术的平方项呈显著正相关。据此，研究建议通过实施更严格的排放标准、鼓励车辆定期保养与尾气检测，以及淘汰超期服役车辆，来管控并降低机动车尾气排放。