What are the main items tested in vehicle exhaust emissions?

[HeidiLynn]

Vehicle exhaust emissions testing primarily examines carbon monoxide, nitrogen oxides, hydrocarbons, photochemical oxidants, and smoke density. The following are reasons for excessive vehicle exhaust emissions: 1. Aging of vehicle components: Due to prolonged use, various parts may deteriorate, leading to noticeably reduced performance and differences in exhaust emissions compared to before. Additionally, older vehicles may have been manufactured using processes that met standards at the time but now fall short due to advancements in production technology and stricter emission regulations, making them more prone to exceeding emission limits. 2. Poor fuel quality: The quality of fuel also impacts vehicle exhaust emissions. Imported vehicles, especially high-end models, often require higher-quality fuel. However, fuel quality in some remote areas of the country may not meet the necessary standards. Long-term use of substandard fuel can easily result in excessive emissions, leading to failure in annual vehicle inspections.