How would it help urban air quality if I retrofit my truck or my bus ?

Diesel engines are the main power system for heavy-duty and non-road vehicles in Europe. These reliable, fuel-efficient, high torque engines power many of the world's heavy-duty trucks, buses, and non-road vehicles such as construction and agriculture machineries.

While diesel engines have many advantages, they have the disadvantage of emitting significant amounts of toxic particulate matter (PM) and nitrogen oxides (NOx) into the atmosphere. Health experts have concluded that those pollutants adversely affect human health and contribute to acid rain, ground-level ozone and reduced visibility. Studies have shown that exposure to diesel exhaust causes lung damage and respiratory problems and there is increasing evidence that diesel emissions may cause cancer in humans.

Based on a comparison of vehicles of early 90's and future Euro VI (2013-14) standards, European legislation will have led to emissions reductions for heavy-duty engines of 97% on NOx and PM in less than 25 years. Thus new vehicles become clean but the legacy fleet of old heavily polluting vehicles still largely contributes to urban air pollution issues since fleet penetration appears to be a 15 to 20 year process and limits rapid progress to the targeted air quality benefits.

A research project was conducted in 2006 for the European Commission on how the EU can support the greater use of technical measures such as emissions control systems that can help reduce the emissions of particulates and NOx from existing heavy duty and captive fleets.

Low Emissions Zones are progressively implemented in many urban areas in Europe and these request diesel vehicles to meet a satisfactory level of exhaust emissions before they are allowed to drive inside the zone.

Companies that manufacture emission control devices have responded to the challenge of reducing the air pollution from diesel engines. Through their efforts, cost-effective retrofit technologies have been developed to reduce harmful emissions. Within the various mobile source sectors (e.g., trucks, urban buses, construction, mining and materials handling machines), diesel retrofit technologies have demonstrated their ability to significantly reduce unwanted emissions at reasonable costs without jeopardizing vehicle or machine performance.