The exposure of workers with regard to the thresholds mentioned in Article D. 4163-2 is assessed after the application of collective and individual protection measures.
When the minimum duration of exposure is calculated in terms of the number of hours per year, exceeding the threshold is assessed by adding together the durations during which each of the actions takes place or during which each of the situations is observed.
When, for the application of article D. 4163-2, the employer assesses the exposure of a worker to night work, he does not take into account the nights worked in successive alternating shifts.