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

Working Safely in the Hazardous Zones of Industrial Machines

  •   March 16, 2017

Montréal, March 16, 2017 - The findings of a scientific study suggest some safety guidelines for workers carrying out maintenance or repairs on industrial machines operating in reduced speed and force mode (i.e., reduced energy). Section 189.1 (previously 186) of the Quebec Regulation respecting occupational health and safety (ROHS) provides a regulatory framework designed to prevent situations in which moving parts can cause serious or even fatal occupational injuries. Nevertheless, the provision does not indicate any specific speed, force, contact pressure or energy values to be met. The researchers began their study by assessing current knowledge about these values. They then visited 9 companies and studied 16 situations involving work on machines in order to understand how companies go about applying ROHS section 189.1.


The study provided an opportunity to conduct a survey of the speed, force, contact pressure and reduced energy values proposed in the literature (standards, guides, scientific papers) and present them with their references. The researchers found that machines are not always designed on the basis of the requirements of section 189.1 and that workers who enter hazardous or danger zones do not always use a hold-to-run control or an inching/jogging advance mode. In addition, while most machine speeds observed in factory settings are equal to or lower than the standards, some maintenance or repair jobs are done at production speeds. The reduced energy levels recommended in the literature depend on many factors, and the wide variety of possible situations means an in-depth risk analysis should be conducted. The application of ROHS section 189.1 is therefore an integral part of the risk assessment and reduction process for tasks where workers have no alternative but to enter the zone where machine parts are in motion.


“If the situation concerning the reduced energy levels to be used in a factory setting corresponds exactly to the context described in the literature, then workers may use those same values. On the other hand, when no reference is available, the determination of a tolerable energy level must be based on more extensive thought and analysis. Only a thorough comparison of the context of the proposals made in the literature and that of the real situation will allow extrapolation of the recommendations to comparable, but not identical situations,” noted lead author Yuvin Chinniah, an engineer and associate professor in the Department of Mathematics and Industrial Engineering at Polytechnique Montréal.

The study, published by the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST), can be downloaded free of charge from

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Jacques Millette
Public Affairs