When an entrant is at an LEL, they are usually way beyond the PEL/TLV/STEL

When we talk about Lower Explosive Limits, most people imagine a flash-fire hazard (as they should!). But when a worker is in a flammable atmosphere, they are also being WAY OVER EXPOSED. Take the following OSHA PRCS fatality case, where the worker died from being overexposed to organic vapors. The Atlantic City Fire Department Confined Space Rescue Team had measured approximately 3% the LEL for these vapors at the time they removed the deceased from the tank.

The LEL of Toluene/Xylene is 1.1% or 11,000 ppm. 3% of 11000 is 330 ppm. The PEL for Toluene is 200 ppm, and Xylene is 100 ppm. So we can say this was a gross overexposure event. Add that the worker may have been working 12-hour shifts, rather than the normal 8 hours on which the PELs are based. The medical examiner’s report stated that death was caused by an overexposure to organic vapors consistent with those found in the paint formulation (MiBK, Toluene, Xylene).

An employee was painting the interior of a 15,000-gallon water storage tank with epoxy primer paint. An airless spray was being used for this task. An organic vapor air purifying respirator was in use and three small exhaust fans were drawing from the 12-in. pipe openings in the tank. The employee was found dead at the bottom of the section of the tank that was used for initial filling and settling. There was no confined space program or procedure in place at the time of the incident and the employee was working alone without the knowledge of the supervisor(s). The medical examiner’s report stated that death was caused by an overexposure to organic vapors consistent with those found in the paint formulation (MiBK, Toluene, Xylene). The Atlantic City Fire Department Confined Space Rescue Team had measured approximately three of the LEL for these vapors at the time they removed the deceased from the tank.