This is an investigative report of the March 16, 2016 hydrogen/oxygen explosion at the University of Hawaii at Manoa campus (UH), in which a postdoctoral researcher lost her arm and sustained burns to her face and temporary loss of hearing. The postdoctoral researcher was working in a laboratory at the Hawaii Natural Energy Institute in the Pacific Ocean Science and Technology (POST) building. The University of California Center for Laboratory Safety, in its capacity as an independent third party review team, was contracted to investigate the circumstances that led to this laboratory accident. The report is separated into two sections. The immediate cause of the accident was traced to the digital pressure gauge which acted as a path to ground for a static charge that ignited the hydrogen/oxygen gas mixture contained within a 13 gallon (50 liter) pressure tank. Extensive analytical testing of an identical gas tank/pressure gauge system did not reproduce a stray electrical current within the digital pressure gauge suggesting that the initiation event was due to a static discharge generated in the tank or the researcher. The explosive gas mixture was most likely ignited when the statically charged researcher touched the metal housing of the gauge and a charge transfer occurred causing a corona or brush discharge within the gauge stem. While the likely point of initiation of the explosion was determined to be due to static discharge through the digital pressure gauge, it should be emphasized that there are numerous means by which a hydrogen/oxygen gas explosion can be initiated. It is imperative that, hydrogen/oxygen gas mixtures in the explosive range should not be stored, and experiments using hydrogen/oxygen gas mixtures, such as the culture of hydrogen-oxidizing bacteria, should undergo rigorous hazard analysis and mitigation efforts to eliminate possible sources of ignition.
This accident at the UH laboratory showcases once again the challenges that academic research laboratories face in addressing physical hazards of experimental processes and recognizing potential hazardous consequences when experimental procedures are changed. In scientific research the experimental outcome often becomes the driving force and overrides risk considerations. In this respect, the UH lab explosion is similar to the explosion at Texas Tech University and the fire at UCLA. Based on the report of the explosion at Texas Tech University by the Chemical Safety Board (CSB), OSHA has amended its regulatory standards by establishing non-mandatory recommendations regarding physical hazards in the laboratory including combustible liquids, compressed gases, reactives, explosives and flammable chemicals, as well as high pressure/energy procedures, sharp objects and moving equipment.
The key lessons identified in the CSB report are directly applicable to UH and are included as several of the safety recommendations to UH. This report was written to serve as a direct call to action for researchers, administrators and EHSO staff not only at the UH, but at all institutions of higher education that conduct research. The recommendations and lessons learned contained herein should be understood and addressed at all universities in order to help prevent laboratory accidents.
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