STAFF at a Wiltshire chemicals company needed hospital treatment after a mistake caused a huge cloud of toxic gas to spread across the site.

An accidental chemical reaction caused chlorine to fill the GEA Farm Technologies UK factory in Warminster as well as the nearby yard and surrounding area on June 12 2019.

After investigating the incident, the Health and Safety Executive has now slapped the business with a hefty £40k fine for causing the dangerous hazard.

The gas cloud formed when an intermediate bulk container with 700kg of concentrated sulphuric acid was poured into a mixing vessel which already contained 1,600 litres of sodium hypochlorite solution.

The chemical reaction that followed caused what the HSE describes as "significant damage" to the factory, and resulted in staff being rushed to hospital with breathing difficulties because there was no clear evacuation plan in place for the on-site workers.

Luckily, none of the employees affected by the caustic cloud suffered long-term health issues.

Chlorine gas is irritating and corrosive to the eyes, skin, and respiratory tract. Anyone exposed to it will soon feel their eyes, nose, and throat burning, and it may make their airway and lungs tighten.

A Health and Safety Executive investigation found the incident happened because a dedicated mixing plant had not been brought back into service after maintenance work, and the company had failed to introduce effective records management for the temporary manual system.

CCTV footage showed the full extent of the gas cloud's reach.

GEA Farm Technologies (UK) Ltd is based on Watery Lane in Warminster.

Salisbury Journal: GEA's Warminster site. Picture: Google MapsGEA's Warminster site. Picture: Google Maps (Image: Google Maps)

A representative for the company pleaded guilty to breaching Section 2(1) of the Health and Safety at Work etc. Act 1974.

The firm was fined £40,000 and ordered to pay costs of £22,000 at Basingstoke Magistrates’ Court on October 4 2022.

Speaking after the hearing, HSE inspector Malcolm Whyatt said: “In this case, several workers were put at risk from a cloud of chlorine gas which drifted uncontrolled through their workplace.

“The company had previously designed their system to eliminate the possibility of human error - by reverting to a manual process, they created a situation where mixing incompatible chemicals was possible.

"Chlorine can have severe health effects at very low levels, and they were fortunate that no-one was more seriously injured.”

GEA describes itself as a leading supplier of complete lines and unit operations to the chemical industry, producing a wide range of bulk and specialty chemicals.