INRS emphasizes prevention to fight against the cost of work stress and seeks to develop methods and tools objectification stressful situations. The social cost of workplace stress would represent 10 to 20% of the expenses of the branch for employment injuries / occupational diseases of the Social Security According to a survey by the European Agency for Safety and Health at Work conducted in 1999, stress is the cause of 50 to 60% of all lost working days. The cost of occupational stress assessed by INRS represent 830 million euros in 2000 in France.