On Thursday, August 27, 2026, MIT Emergency Management announced the closure of Building 18 after a graduate student self‑reported exposure to a hazardous material—dimethyl mercury—in a second‑floor chemistry lab. Emergency responders worked overnight to secure the site, and the institute launched specialized decontamination procedures. Support resources for the affected student and the broader community were made available (e.g., https://doingwell.mit.edu/support/ and https://health.mit.edu/mit-mit/employees/employee-support-programs).
By August 28, decontamination was still underway and the building remained closed. Officials stressed that the incident was isolated to a single individual, the use of the compound was unauthorized, and, based on assessments by industrial hygienists, MIT Health medical experts, and external consultants, the risk of secondary or tertiary exposure was very low.
An update on August 29 reported that the student had presented to a local emergency department, where blood tests showed no evidence of mercury exposure. Laboratory decontamination was largely completed, and the student remained under medical supervision. High‑touch surfaces in the surrounding residence hall were professionally cleaned, and the sealed unit in the residence hall continued to be decontaminated, though the hall itself stayed open. Baseline testing was offered to individuals who had been in proximity to the lab on August 26; community members who did not enter the lab were not advised to undergo testing.
At 10:16 p.m. on August 30, MIT announced that all decontamination work was finished and that Building 18 would reopen at 6 a.m. on Monday, August 31. The sealed residence unit had also been cleared, and the residence hall remained in normal operation. A campus map is available at https://whereis.mit.edu.
Review: This incident highlights MIT’s robust safety, emergency response, and cross‑department coordination protocols. Even when a potentially high‑risk chemical spill is suspected, the institute swiftly isolated the area, deployed professional decontamination, provided medical monitoring, and kept the community informed, thereby minimizing secondary exposure risk. Future improvements could focus on tighter control of chemical authorizations and encouraging proactive self‑reporting to prevent unauthorized synthesis attempts.