NO_X emission deterioration in modern trucks: Evidence from remote sensing

Area of Science:

• Environmental Science
• Transportation Engineering
• Atmospheric Chemistry

Background:

• Diesel trucks are significant sources of nitrogen oxides (NOx) emissions.
• Understanding NOx emission deterioration is crucial for accurate air quality modeling and regulation.
• Euro V and Euro VI emission standards aim to reduce NOx pollution from heavy-duty vehicles.

Purpose of the Study:

• To analyze the deterioration of NOx emissions in Euro V and Euro VI ABC diesel trucks.
• To quantify NOx emission rates and trends with increasing mileage.
• To identify and characterize high-emitting trucks and their contribution to overall pollution.

Main Methods:

• Utilized remote sensing data from Belgian and Swiss highways.
• Classified trucks into rigid, tractor-trailer, and articulated types.
• Analyzed NOx emissions and NOx/NOx ratios considering temperature and mileage, focusing on data between 15-25°C.

Main Results:

• NOx emissions increase linearly with mileage; the NOx/NOx ratio decreases polynomially.
• Euro VI ABC tractor trailers show a deterioration rate of 0.09-0.15 g/kg fuel per 100,000 km, a 60-70% increase over 700,000 km.
• A subset of high emitters (Euro V >20 g/kg fuel, Euro VI >7 g/kg fuel) increases highway NOx emissions by 30-50% and their proportion grows with mileage.

Conclusions:

• Most trucks remain compliant, but high emitters significantly impact air quality.
• Findings support updates to emission factors for improved inventorying and regulation.
• Addressing high emitters is key for achieving air quality goals under Europe's Zero Pollution Ambition.