Ventilation and smoke removal of public underground car parks

Car Park Gas Monitoring  


As managers of public car parks, you must comply with several regulatory standards regarding the ventilation and smoke removal of premises. These regulations are defined by the technical instruction of 3 March 1975. They impose ventilation measures intended to:

  • Limit the concentration of harmful or flammable gases in your car parks;
  • Avoid stagnation that could endanger staff or users.

The standards to meet for your parking lots

  • The instantaneous carbon monoxide content should not exceed 150 ppm;
  • The average exposure value (AEV) to carbon monoxide shall not exceed 20 ppm;
  • The threshold limit value – short-term exposure (TLV-STEL) is 100 ppm.

These values must be respected regardless of the carbon monoxide content of the air to be sampled inside. In parking lots that can accommodate diesel vehicles on over 30% of their surface area, the setting of a limit value may also be imposed for other pollutants.

With regard to gas detection, industry professionals must follow the opinion of 14 December 1998 published in BO number 99/7. The latter recommends limit values for carbon monoxide and nitric oxide concentration:

CO content​​​
Instant value 150 ppm
About 15 minutes 90 ppm
About 30 minutes 50 ppm


As a parking operator, you are responsible for these goals. There are several solutions that can help you answer this, including the installation of a gas detection system with control unit and detectors controlling ventilation and the triggering of an emergency signal.

Gas detection: what obligation for car parks?

Underground and public car parks subject to the regulation of classified facilities are obliged to install carbon monoxide detectors, as well as nitrogen oxide detectors for infrastructures hosting over 500 vehicles.

Whether or not you are affected by this obligation, installing an automatic detection system is highly recommended to improve the safety and operation of the processes in comfort and smoke removal mode for car parks. Teledyne Gas and Flame Detection devices perfectly meet these requirements, whether it be our carbon monoxide detectors, or our nitric oxide detectors.​​​​​