A university swimming pool and gym had to be evacuated after a handyman accidentally made a gas used in warfare, a tribunal found.

Anthony Brown was asked to top up chemicals and test pool water at the University of Hertfordshire when the incident occurred in October 2024.

While doing this, he ‘wedged open’ the chlorine tap with a piece of wood before answering the phone and stepping out.

When he returned, he discovered the tank had overflowed and sodium bisulfite – a chemical used to keep shrimp fresh – had spilt in another room.

But when attempting to clean up both messes with a vacuum designed for liquids, he ‘inadvertently’ made mustard gas, a tribunal heard.

Brown, who had been employed by the firm for seven years, was dismissed the following month and challenged the decision in court.

The tribunal heard that Brown began to feel the side effects of the agent, so alerted his manager and phoned 999.

Sulphur mustard gas is an amber-coloured fluid that causes severe burns to the skin, eyes and lungs.

The fire brigade evacuated the university swimming pool and gym.

‘They were quickly satisfied that there were no casualties (except the claimant himself, who required paramedic surveillance) and that the pool could be reopened to the public,’ the tribunal judge said.

Brown’s employer, the facilities management company Pinnacle FM Limited, investigated and found his ‘good deed’ increased the ‘risk of harm’.

‘The investigation report concluded that the incident could have been avoided, including the fact that the Claimant had inappropriately jammed open the handle, allowing the overfilling of the chloride day tank,’ the tribunal said.

Employment Judge Cowen concluded that Brown’s training for dealing with chemical spills was ‘essentially one paragraph in a 200-page handbook’.

The tribunal dismissed Brown’s claims of wrongful and unfair dismissal last month.

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.’

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