Why Level B is the MINIMUM for 1st Entry

It comes from this requirement in OSHA’s HAZWOPER standard and has sound logic behind it… (emphasis by me)

I spend anywhere from 2-3 hours in a 24-hour Tech course. In my 40-hour Tech course I spend an additional hour just on Respiratory Protection because this single OSHA requirement is rarely fully understood by those attending a Tech level course.  I teach this concept by asking…

What are the four (4) pieces of atmospheric-related data we MUST know to go from a Positive-Pressure SCBA (APF=10,000) used in LEVEL A and B ensembles down to a LEVEL C ensemble that uses an Air-Purifying Respirator (operating in a negative mode and has an APF of 50)? 

Quite the change from an APF of 10,000 to 50, so we MUST fully understand these four (4) bits of data to assess the needed RP…

#1 – The hazardous substance involved

This may be easy to obtain in many cases due to the container labeling.  But without proper labeling, this is 100% an UNKNOWN.  In some cases, where I see a contradiction between how the HAZMAT is behaving once it exits its container and what the container label is saying, I will ALWAYS manage this as an UNKNOWN and an UNKNOWN environment is ALWAYS managed as an IDLH environment (1910.134(d)(1)(iii))

#2 – The concentration of the hazardous substance involved

This was NEVER known to us upon arrival!  Even if the process area has fixed detectors, we NEVER utilize the reading from those fixed detectors (which could be 30′ in the air) when assessing our RP needs.  Those detectors are part of a Safety Instrumented System (SIS) to activate alarms and engineering controls to alert personnel of a leak and aid in controlling the concentration within the space.  The ONLY means we should rely on, and even then we MUST understand the limitations of our meter, is to measure the atmosphere with a CALIBRATED and BUMP-TESTED handheld meter that can read what we believe the SPECIFIC hazardous substance is involved.

#3 – The concentration of the hazardous substance involved is BELOW its IDLH limit

I always teach my techs, look up the IDLH limit for said substance from at least THREE(3) REPUTABLE SOURCES and stamp it into your brain!  NEVER EVER LOSE SIGHT of that IDLH.  I tell them this on day one and I openly tell them that on Day 3/5 they will walk the plank to death in their scenario/drill if they lose sight of the IDLH.  Why is this bit of data so critical? 

1. The MUC formula ONLY works when we are below IDLH (1910.134(d)(3)(i)(B)(2)
2. The ONLY RP allowed in an IDLH atmosphere is a positive pressure self-contained breathing apparatus (1910.134(g)(3)(vi)(A)

If we lose sight of the IDLH while using the MUC formula, that formula WILL equate such that we could be fooled into wearing the wrong RP in an IDLH atmosphere.

#4 – The atmosphere has at least 19.6% Oxygen

To wear something less than a positive pressure self-contained breathing apparatus, we have to KNOW the O2 levels, as the GREATEST LIMITATION of an APR is that it does not provide Oxygen – it merely filters the KNOWN contaminant.  And for the record, there is NO WAY IN HELL that I would wear an APR if my O2 readings are anything less than 20.5% (Normal at sea level being 20.8%).  Since I would NOT do this myself, there is even LESS chance I would send someone else into such an atmosphere!

So ask yourself…

When you arrive at the release, maybe you can see the hazardous substance and IDENTIFY it by labeling and its behavior outside of its primary containment.

We will NOT know #’s 2-4. 

To obtain this data, we must ENTER the HOT ZONE with proper instrumentation to obtain #2 and 4. 

#3 will be obtained from the NIOSH pocketguide, SDS, recognized software data, etc.

If we do NOT have ALL four (4) pieces of this data, we can NOT wear LEVEL C (an APR for RP).  The minimum LEVEL is B, which is an SCBA FOR RP.

Then we have to decide on LEVEL A or B and that is another dioscussion for another day.