Three workers were burned Tuesday afternoon when sodium hydroxide flashed during silo cleaning inside an Otay Mesa sugar refinery, according to Cal Fire. One victim is reportedly in critical condition, while the other two suffered moderate injuries, as the industrial accident forced a building evacuation that escalated into a shelter-in-place order during extreme heat.
The first call came in around noon reporting a hazmat situation with injuries, as reported by FOX 5 San Diego & KUSI News. The three burn victims had been cleaning a silo inside the refinery when sodium hydroxide flashed. City and county units also responded to the scene as the situation developed.
Evacuation Escalates as Temperatures Climb
What began as a building evacuation reportedly turned into a shelter-in-place order, one prompted in part by extreme heat in the area. The heat added another layer of risk for responders and anyone still near the facility.
Separate reporting from KGTV identified the cleaning chemical involved as sodium hydroxide, commonly known as lye or caustic soda. That outlet's reporting also updated the severity of the injuries, indicating one of the three workers suffered critical burns while the other two sustained moderate injuries — a somewhat different picture than the moderate-to-critical breakdown reported by Cal Fire to Fox 5 San Diego. The available reports do not identify what caused the flash.
What Cal/OSHA Rules Likely Apply
Cleaning industrial silos and storage tanks in California falls under permit-required confined space rules codified in Title 8 Section 5157 of the California Code of Regulations, which include a written permit program and attendant protocol, according to the California Department of Industrial Relations. Separately, Cal/OSHA's Title 8 Section 3314 requires facilities to follow strict lockout/tagout procedures during equipment cleaning to prevent accidental chemical or thermal discharges, per the same state guidance. It remains an open question whether the Otay Mesa refinery was following either protocol at the time of the flash reaction.
California facilities handling hazardous chemical releases may fall under HAZWOPER requirements under Title 8 Section 5192, depending on the standard's applicability and training thresholds. What specific catalyst triggered Tuesday's reaction has not been disclosed.
A Growing Industrial Corridor With a Recent History of Hazmat Emergencies
The incident lands in an industrial part of San Diego County. The incident also involved sodium hydroxide, an industrial chemical.
Otay Mesa has faced major hazmat emergencies before. In May 2024, a fire at the Gateway Energy Storage facility burned for 11 days, from May 15 to May 27, and involved extensive amounts of water pumped into the facility's sprinkler system. The fire triggered an evacuation warning for nearby areas and a shelter-in-place order for Donovan State Prison — a response Hoodline covered as it unfolded. That prolonged emergency unfolded over 11 days.
Industrial sugar processing facilities carry their own historical safety concerns. The available reporting does not establish whether a 2008 Georgia sugar refinery explosion involved hazards similar to those in Tuesday's incident. Whether similar hazards played any role in Tuesday's flash reaction has not been addressed by investigators.
The condition of the critically injured worker and the specific catalyst behind the reaction remain unresolved as of Tuesday evening. Cal Fire has not indicated whether a formal Cal/OSHA workplace safety investigation has been opened into the incident.
