Section 1: Definitions and general provisions

The provisions of this chapter apply whenever workers are exposed to a relative pressure of more than 100 hectopascals in the course of the following activities carried out with or without immersion: 1° Hyperbaric work carried out by companies subject to certification, the list of which is set by the order provided for in Article R. 4461-48, taking into account the nature and extent of the risk, including in particular…

The relative pressure considered by this chapter is the absolute pressure at the level of the worker’s airways, at the moment when it reaches its maximum value during the working time, less the local atmospheric pressure.