Why are diesel vehicles subject to different emissions standards than gasoline vehicles?

Diesel vehicles are subject to different emissions standards compared to gasoline vehicles primarily because diesel engines produce different types and quantities of pollutants. Diesel combustion leads to the formation of nitrogen oxides (NOx) and particulate matter (PM) at levels that can be significantly higher than those from gasoline engines. These emissions can have different impacts on air quality and public health, thus necessitating distinct regulatory standards to address the specific challenges posed by diesel exhaust.

The unique combustion characteristics and fuel composition of diesel contribute to its distinct emission profile. As a result, regulatory agencies establish tailored emissions standards that reflect the specific environmental and health concerns associated with diesel pollutants, ensuring they align with efforts to improve air quality and protect public health.