If we spend enough time in chemical plants, we will encounter a widespread, albeit severe, human failure regarding a “safety-critical instrument.” I am referring to the IMPROPER placement of personal gas monitors. Nine times out of 10, where do we find these personal gas monitors on the worker’s body? I am betting your experiences are similar to mine and you would answer “back of the worker’s hard hat”. The problem with this convenient location is that it is NOT in the worker’s “breathing zone.”
What is our “breathing zone”?
OSHA and NIOSH DEFINE and QUANTIFY the “breathing zone” as:
Breathing zone (i.e., in a hemispheric area forward of the shoulders within a 6-to-9-inch radius of a worker’s nose and mouth…”
Source: OSHA Technical Manual (OTM), Section II: Chapter 1
As we can see from the OSHA image, wearing an air sampling device on the back of a hard hat is OUTSIDE the worker’s breathing zone. Even some of the more common hard hat adapters I am seeing these days, albeit an improvement over the back of the hard hat, clip the meter onto the side of the hard hat, which could be located outside the worker’s breathing zone. AND YES, I may be splitting hairs (as some would call it), but this is why we DEFINE and QUANTIFY safety-critical measures! And I think most of us are familiar with the old saying… “give them an inch, and they’ll take a mile.” I’m just saying inches matter!
Using one of my favorite resources from MSA, we see the “placement” as specified:
Source: https://us.msasafety.com/fgfd-gas-detection-handbook?locale=en
So where are these devices to be worn?
The only place we ever permitted was on the front collar area. Not even on a pocket, as that too is OUTSIDE of the prescribed “breathing zone.”
Another acceptable location is on the shirt’s placket BETWEEN the top button and 1st button, as shown below:
