Abstract

The establishment of occupational exposure standards for hazardous substances, specifically permissible exposure levels (PELs), has been a major factor in preventing occupational disease. However, these standards were developed on the basis of a traditional work schedule of eight hours per day, five days per week. In order to ensure that all workers enjoy the same level of protection, the IRSST asked group of toxicologists to develop a PEL-adjustment method for non-traditional work schedules. To facilitate the real-world application of these adjustments by industrial hygienists, the toxicologists defined the conditions under which adjustment is appropriate and provided a structured approach to the adjustment of exposure limits, and a calculation method.