From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> on behalf of James Kaufman <jkaufman**At_Symbol_Here**LABSAFETYINSTITUTE.ORG>
Date: Monday, March 28, 2022 at 1:29 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Subject: [DCHAS-L] Recent Lab Accident

Accident Date: 2022-02-17
Injuries? A researcher (with ca. 8 years of research experience) was injured. She was not working on the experiment at the moment of the explosion but she was standing close to the glove box where the explosion occurred. Injuries include: some wounds on her face/neck, a tooth avulsion and the mobility of other 7 teeth, the fracture of the left lamina of the 6th cervical vertebra, maxillary sinus fracture. The researcher was taken to the ER and hospitalized for one week. Surgical intervention was provided the night of the accident to close the wounds and clean them (several tiny glass pieces were all over her face and hair and clothes). Luckily the wound on the neck did not impact the blood vessels, vocal cords and trachea. Also the researcher was wearing her personal eyeglasses, which probably protected her eyes. She is fine now, still wearing a neck brace (the prognosis was 45 days). Provisional splinting was applied to mobile teeth, while an implant will be necessary to replace the avulsed tooth.

The injured researcher is also the author of this report.
Accident Description: The researcher was conducting an experiment to test the activity of a catalyst for the oxygen reduction reaction (for application in fuel cells). The catalyst is composed mainly of carbon and some metal traces and it is deposited as a thin film on the tip of a rotating ring disk electrode. The electrode is immersed in an electrochemical cell together with other two electrodes. The cell contained an aqueous solution 0.1 M KOH. Since the goal of the exp was to evaluate the durability of the catalyst, the test was supposed to last for a few days, therefore the exp was conducted inside a glove box (called in the lab "wet box" because the use of solvents and water was permitted inside it, differently from traditional dry boxes). The electrodes were connected through cables to a potentiostat located outside the box. Inside the box there was also a magnetic stirrer that was on all the time, mixing some closed vials containing (non flammable) solutions of another student in the group. The glove box is under constant N2 flow. The researcher started the experiment in the morning. The first step implies the use of hydrogen gas that was delivered from a cylinder in the room to the electrochemical cell. The solution in the electrochemical cell is saturated with H2 to measure the potential of the reference electrode. The second step implies the use of O2 gas: the solution in the cell is saturated with O2 and the activity of the catalyst is measured. The researcher completed these steps in the morning, noticing though a noisy electrochemical signal in O2 and a measured potential of the reference electrode that was 40-50 mV off her expectations. She shared what she noticed with other people in the group. Since she had also to help a student with another experiment, she stopped her experiment at around 11 am (H2 and O2 cylinders were both closed and only N2 was flowing in the box) with the intention of restarting in the early afternoon. After lunch at around 1.30 pm she was close to the wet box trying to decide how to proceed, when an explosion occurred inside the box. The researcher has no memories of the moment of the explosion and she was alone in the room at that moment. The first memory is immediately after the explosion: she was a bit farther from the box, but still standing, she realized that there was blood running on her face and that she was alone, but in that moment a student of the group entered so she asked to call the ambulance and walked to the nearby small office to sit down on a chair where she remained until doctors arrived. She always remained conscious. Her colleagues didn't call immediately the ambulance because they first try to reach by phone the professor and older group members. A technician of the department called the ambulance.

An investigation is still open, so the precise causes are not yet officially defined. However, such an explosion is likely caused by the presence of hydrogen and oxygen inside the box. It is unclear why the gases remained inside the box for hours and what was the ignition source.