Vehicles are the source of many pollutants discharged in the atmosphere, in addition to CO2. These pollutants affect the air quality. In high concentrations, they can be harmful to the environment and to human health. European standards define the legal limits for emissions of these pollutants. 

Pollutants and health problems

The main pollutants are:

• Carbon monoxide (CO): it causes asphyxia, respiratory and cardiovascular disorders.
• Unburned hydrocarbons (UHC): they are part of a broader category called "volatile organic compounds" (VOCs). They cause cancer and contribute to the formation of ozone in the atmosphere.
• Nitrogen oxides (NOX): they cause respiratory and cardiovascular disorders and contribute to the formation of ozone in the atmosphere.
• Particulate matter (PM): they cause respiratory and cardiovascular disorders.
• Sulphur dioxide (SO2): it causes acidification disturbing the fauna and the flora.

Pollutant emission standards

The emission of pollutants varies widely depending on the fuel used.

Petrol, for example, emits more carbon monoxide (CO) and unburned hydrocarbons (UHC), diesel on the other hand emits more nitrogen monoxides (NOX) and particulate matter (PM). In case of SO2 emissions, it depends on the sulphur content of the fuel. This content is legally fixed.

EURO standards define the legal limits of CO, UHC, NOx and PM that each vehicle must meet. They are regularly reviewed in accordance with the health requirements and technical advancement.

Specifically, since 2009, EURO 5 standards are mandatory for all vehicles. These standards have imposed a particularly low limit for the particulate matter (PM) emissions and have resulted in the widespread use of particulate matter filters.

In 2014, the subsequent EURO 6 standards are specifically targeting the nitrogen oxides (NOX).

Heavy metals

Lead, mercury, cadmium and hexavalent chromium are heavy metals, metals hazardous to health. Other than in a few specific parts, they are banned in cars.


When vehicles reach the end of life, they should be handled in specialised centres.

They are emptied of their pollutants (fuel, oil, etc.) and dismantled. Most of the vehicle is recycled. The remaining materials and substances are valorised as fuel and/or put in a landfill.

Who monitors the air quality in Belgium?

Regional authorities are responsible for the air quality and are therefore responsible for the concentrations of pollutants in the air.

• Flanders: The Flemish Environment Agency (VMM, Vlaamse Milieumaatschappij)

• Brussels: the Brussels Institute for Management of the Environment (IBGE-BIM, Institut Bruxellois pour la gestion de l’Environnement)

• Wallonia: Walloon Agency for Air and Climate (AWAC, Agence Wallonne de l’Air et du Climat)