Background Information

Even though the federal OSHA Permit Required Confined Space Entry Standard (PRCS), 29 CFR 1910.146, contains specific requirements for pre-entry and follow-up atmospheric monitoring people continue to die in confined spaces due to oxygen deficiency and / or exposure to hazardous atmospheres. One only has to look at the Weekly Fatality / Catastrophe Reports on the federal OSHA website ( for evidence. The question is, why?

Having worked in the industry for over 40 years I have and continue to see major problems with companie's Confined Space Entry Atmospheric Monitoring Programs, both in the United States and abroad. The problems generally fall into one (1) of three (3) categories:

  1. Use of defective monitors or ones that have not been correctly calibrated

  2. Incorrect use of the equipment

  3. Failure to correctly interpret the results of the monitoring

In almost every case the root cause is the lack of training on the part of the monitor users, their supervisors and managers.

What constitutes an effective gas testing training program? That's a good question. The OSHA PRCS standard is silent on this issue. The ANSI / ASSE Z117.1-2009 Standard1, "Safety Requirements for Confined Spaces", states, "Training shall include the selection and proper use of appropriate atmospheric monitoring instruments based on a current hazard assessment." The explanatory note further states, "It is important for individuals conducting atmospheric tests to possess adequate knowledge of the proper operation of monitoring equipment as well as its limitations associated with anticipated conditions (such as inaccurate measurement readings for flammable gas when the oxygen level is below 16% for certain equipment). Similarly, these individuals should have information about the related process to anticipate potential atmospheric contaminants, such as a nearby reactor containing a highly toxic substance which could endanger the entry team in the event of a leak or release."

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