IRSST - Institut de recherche Robert-Sauvé en santé et en sécurité du travail

Utility for the adjustment of TWA

This computer-based tool allows users to calculate the adjusted average exposure value (AAEV) based on unusual work schedules. The AAEV is calculated from the TWA as defined in the Québec Regulation Respecting Occupational Health and Safety Health.

The adjustment principles are described in the Guide to the Adjustment of Permissible Exposure Values (PEVs) For Unusual Work Schedules (document T-22). It should be noted that, according to these principles, only the TWA should be adjusted. Simple asphyxiants and regulated substances with ceiling values, short-term exposure values or no permissible exposure values are not affected by the adjustment process. However, an adjustment category is also available for these substances to allow users to adapt the adjustment principles to their own limit value system.

Additional Information

  • Daniel Drolet
  • Thierry Petitjean-Roget
Publication no.: UT-011
Version: 2019
Language: French, english
Online since: September 01, 2007
Format: Application / Website