Swimming pool evacuated after handyman mistakenly releases mustard gas

A handyman who accidentally created mustard gas and sparked the evacuation of a university gym and pool was fairly dismissed, a tribunal has found.

Anthony Brown, who worked for seven years for Pinnacle FM Limited, a facilities management company, challenged his 2024 dismissal over the incident, but an employment judge found he “wilfully breached health and safety rules”.

On 12 October 2024, Mr Brown was in charge of topping up chemicals and testing pool water at the University of Hertfordshire, a client of the firm.

While doing this, he “wedged open” the chlorine tap with a piece of wood before answering a phone call and stepping outside. Upon returning, Mr Brown discovered the tank had overflowed.

He continued his duties before discovering another spillage in a different room, this time containing sodium bisulphate.

Mr Brown attempted to clean up both spillages using a vacuum cleaner designed for liquids, draining and flushing it with water.

During this process, Mr Brown started a chemical reaction, with an employment tribunal hearing that he “inadvertently made mustard gas”.

After feeling the side effects, Mr Brown notified his manager, resulting in the fire service being called and the pool and gym being evacuated, while Mr Brown was checked by paramedics.

A short time later, it was declared safe and was reopened.

Following an internal investigation, a report concluded Mr Brown had attempted a “good deed” but had actually “increased the risk of harm to himself and others”.

The investigation found that although Mr Brown had a “long, unblemished service”, he was guilty of a serious breach of health and safety – which could have been avoided. He was subsequently dismissed on 26 November, 2024.

The tribunal found that Mr Brown did not have adequate training in how to deal with spillages, amounting to “essentially one paragraph in a 200-page handbook”, with no direct teaching or training ever carried out on chemical leaks.

But it found that by propping open the valve and walking away, Mr Brown’s actions were the “catalyst” for the chain of events and his conduct amounted to a “deliberate and wilful breach of health and safety rules”.

The tribunal dismissed his claims of wrongful and unfair dismissal on 4 September 2026.

A Pinnacle spokesperson said: “The safety of our colleagues, clients and customers is our absolute priority. Following this incident, a full investigation was undertaken.

“At the conclusion of that process, this colleague’s employment was terminated. We take incidents of this nature extremely seriously and are committed to maintaining the highest standards of health and safety across our operations.”