Recently OSHA rescinded all their previous LOIs regarding how to calculate your HHC in your process when it is NOT in pure form. Since then I have fielded dozens of phone calls and countless emails asking questions about OSHA’s change and how it impacts their process. OSHA’s new enforcement policy is as follows:
In determining whether a process involves a chemical (whether pure or in a mixture) at or above the specified threshold quantities listed in Appendix A, the employer shall calculate:
(a) the total weight of any chemical in the process at a concentration that meets or exceeds the concentration listed for that chemical in Appendix A, and
(b) with respect to chemicals for which no concentration is specified in Appendix A, the total weight of the chemical in the process at a concentration of one percent or greater. However, the employer need not include the weight of such chemicals in any portion of the process in which the partial pressure of the chemical in the vapor space under handling or storage conditions is less than 10 millimeters of mercury (mm Hg). The employer shall document this partial pressure determination.
So how does this apply in real-life?
So in 1910.119 Appendix A, OSHA uses 44% ammonia in a solution as the concentration threshold. Meaning that if your solution had more than 44% ammonia in it, then you would have to calculate the weight of the Ammonia in the solution AND if the weight of ammonia ONLY exceeded the 15,000 pounds threshold, your process would be covered.
EPA’s RMP follows the similar methodology, but their concentration for an Ammonia solution is only 20% with a Threshold of 20,000 pounds. In EPA’s RMP rule there are four (4) toxic substances that have listed concentrations:
- hydrochloric acid — 37% or greater;
- hydrofluoric acid — 50% or greater;
- nitric acid — 80% or greater; and
- ammonia — 20% or greater.
If you have any of these substances in a solution AND their concentration is LESS than the listed concentration, you do NOT need to consider them at all. This means that if I had 1 million gallons of 19% Ammonia solution, it matters NOT how many pounds of ammonia I have in that 1 million gallons; but if the ammonia was at 21% then I would have to determine the weight of the ammonia in the solution and use that to calculate the quantity present. If that quantity is greater than the threshold, the process is covered.
For example, aqueous ammonia is covered at concentrations above 20%, with a threshold quantity of 20,000 pounds. If the solution is 25% ammonia, you would need 80,000 pounds of the solution to meet the threshold quantity of 20,000 pounds. (e.g, 80,000 X 0.25= 20,000);
If the solution is 44% ammonia, you would need 45,455 pounds of the solution to meet the threshold quantity of 20,000 pounds. (e.g. 45,455 X 0.44 = 20,000.2)
Weight X % Concentration = amount of HHC/EHS
So what does OSHA’s newly released LOI on concentration mean?
Refer back to “(b)” above – this is what OSHA changed. Any chemical that is NOT assigned a specifically listed concentration, the employer must assume the solution to be an HHC chemical if the HHC is present in the solution in concentrations GREATER THAN 1%.
So it is easier for me to list those chemicals that have an assigned percentage as there are only eleven (11) of them:
- Ammonia solutions (>44% ammonia by weight) = 15,000 pounds
- Cellulose Nitrate (concentration >12.6% nitrogen) = 2,500 pounds
- Diacetyl Peroxide (Concentration >70%) = 5,000 pounds
- Ethyl Methyl Ketone Peroxide (also Methyl Ethyl Ketone Peroxide; concentration >60%) = 5,000 pounds
- Hydrogen Peroxide (52% by weight or greater) = 7,500 pounds
- Methyl Ethyl Ketone Peroxide (concentration >60%) = 5,000 pounds
- Nitric Acid (94.5% by weight or greater) = 500 pounds
- Oleum (65% to 80% by weight; also called Fuming Sulfuric Acid) = 1,000 pounds
- Peracetic Acid (concentration >60% Acetic Acid; also called Peroxyacetic Acid)= 1,000 pounds
- Perchloric Acid (concentration >60% by weight) = 5,000 pounds
- Peroxyacetic Acid (concentration >60% Acetic Acid; also called Peracetic Acid) = 1,000 pounds
For these eleven solutions, when concentration of the HHC within the solution is LESS THAN the assigned concentration it is NOT a Highly Hazardous Chemical.
As for the other 130+ HHC’s that do NOT have an assigned concentration with their listing in Appendix A, we have to evaluate the solution when the solution has 1% or more of the highly hazardous chemical.