Swimming Pool Evacuated After Worker Accidentally Makes Mustard Gas

A maintenance worker in England was fired after he accidentally created a dangerous gas at a university swimming pool, forcing an evacuation. Anthony Brown had worked for seven years for a company called Pinnacle FM Limited, which manages buildings and facilities for other businesses. The incident happened on October 12, 2024, at the University of Hertfordshire. A court later ruled that his firing was fair.

Brown was responsible for adding chemicals to the pool water and making sure it was safe. While doing this, he used a piece of wood to prop open a chlorine tap so it would keep flowing. He then answered a phone call and stepped outside, leaving the tap running without anyone watching it. When he returned, he found that the tank had overflowed onto the floor.

After cleaning up the first spill, Brown found a second one in another room. This spill involved a chemical called sodium bisulphate, which helps control the chemical balance of pool water. Trying to help, Brown used a wet vacuum cleaner to suck up both spills. He then rinsed the vacuum with water, not knowing what would happen next.

Mixing chlorine and sodium bisulphate inside the vacuum caused a dangerous chemical reaction. The tribunal heard that Brown had accidentally made mustard gas, a toxic substance that can seriously hurt the lungs, eyes, and skin. Brown began to feel the effects of the gas and told his manager right away. The fire service was called, and the pool and gym were evacuated while paramedics checked on Brown.

Firefighters inspected the building and declared it safe a short time later, and the pool was reopened. An internal investigation found that Brown had been trying to help by cleaning up the spills. However, the report said his actions had actually made things more dangerous for himself and others. The investigation also noted that Brown had a clean work record during his seven years at the company.

Brown challenged his firing at an employment tribunal, saying he had not been given enough training. The tribunal agreed his training on chemical spills was very poor — just one paragraph in a 200-page handbook, with no hands-on practice. Even so, the judge found that propping open the valve and walking away was a deliberate and wilful breach of health and safety rules. His claims of wrongful and unfair dismissal were rejected on September 4, 2026.

Pinnacle FM Limited released a statement after the ruling, saying the safety of its workers and customers is its top priority. The company said it takes incidents like this extremely seriously and is committed to keeping high health and safety standards. The case serves as a reminder of how important proper chemical training is for anyone working with hazardous materials. Even good intentions can lead to serious consequences when safety steps are skipped.