How to distinguish between National 4 and National 5 standards?

[AliyahMarie]

National 4 and National 5 standards can be distinguished based on the production year. Here is an introduction to National 4: 1. Time: The National 4 standard was implemented starting in 2011. Vehicles produced after 2011 comply with either the National 4 or National 5 emission standards. 2. Definition: National 4 refers to the fourth phase of China's national standards for motor vehicle pollutant emissions. The main pollutants emitted by vehicles include HC (hydrocarbons), NOx (nitrogen oxides), CO (carbon monoxide), and PM (particulate matter). 3. Function: By applying technologies such as improved catalytic converter active layers, secondary air injection, and exhaust gas recirculation systems with cooling devices, the standard aims to control and reduce vehicle emissions below specified levels.