What emissions does the EGR system primarily aim to reduce?

The EGR (Exhaust Gas Recirculation) system primarily aims to reduce nitrogen oxides (NOX) emissions. This system works by recirculating a portion of the engine's exhaust back into the combustion chamber. By introducing exhaust gases, which are relatively low in oxygen, the system lowers the peak combustion temperature and reduces the formation of NOX, which is produced at high temperatures.

NOX is a significant contributor to air pollution and can lead to the formation of ground-level ozone, which has harmful environmental and health effects. The EGR system effectively helps to meet regulatory standards for NOX emissions and is a crucial component in modern engine design aimed at reducing the environmental impact of vehicle emissions.