Yesterday, I spoke to around 180 professionals about emergency response and anhydrous ammonia. My presentation’s core was how they could distinguish between an “incidental release” and an “emergency response.” But it was one statement I made in an hour that brought nearly a dozen of those in attendance to come up after my talk to inquire about it. Yep, it was my reference to 1910.120(q)(3)(iv) which states:
Employees engaged in emergency response and exposed to hazardous substances presenting an inhalation hazard or potential inhalation hazard shall wear positive pressure self-contained breathing apparatus while engaged in emergency response, until such time that the individual in charge of the ICS determines through the use of air monitoring that a decreased level of respiratory protection will not result in hazardous exposures to employees.
All but one (the Regional OSHA guy!) came up to see me and wanted to know precisely where this requirement resided and what it required. It was as if this was the FIRST time they had heard of this requirement. All were surprised to hear me say that it was an OSHA REQUIREMENT that they be donned in AT LEAST LEVEL B the first time into their hot zone.
This requirement goes back to the fundamental principle of working in hazardous atmospheres. An unknown atmosphere is an IDLH atmosphere, and the ONLY respirator permitted to be worn in an IDLH atmosphere is a SUPPLIED AIR, most often an SCBA; however, an airline is permitted WITH THE ADDITION of the 10-minute BACK-UP (“hip-air”).
We may know the chemical that is being released and we may even have some indicators of the concentration of said chemical in the general release area; however, I would NEVER ADVISE anyone to use fixed area detectors in this manner! What we do NOT know is the Oxygen Concentration in the release area!
I like to remind my students that there are FOUR (4) pieces of data that we MUST have in order to safely make the call on respiratory protection:
1) Chemical
2) Chemical Concentration
3) Oxygen Concentration
4) IDLH level of the chemical
Without these four (4) pieces of data, there is NO WAY any respectable IC would ever go from a LEVEL B ensemble to a LEVEL C. We must remember that the MUC equation ONLY works when the atmosphere is BELOW the IDLH; once we have entered an IDLH atmosphere, ALL BETS are OFF, and an SCBA (or air-line with hip air) is REQUIRED. SAFTENG Members can read my article from several years ago, “What type of respirator do I need?” in which I lay out the proper use of OSHA’s MUC from 1910.134(d)(3)(i)(B).
So yes, it is a FACT that anyone responding to an UNCONTROLLED RELEASE of a hazardous substance that is indeed an EMERGENCY RESPONSE MUST be donned in no less than LEVEL B PPE. Once they have entered the atmosphere AND they have proper air monitoring equipment in which they can MEASURE their exposure(s), then, and ONLY THEN, can the IC make a REASONABLE assessment of the proper level of respiratory protection, just as 1910.120(q)(3)(iv) tells us.