Westminster Magistrates’ Court heard that on 4 September 2015, 30-year-old Paul Tilcock was found dead by the owner of house in Mitcham on the bathroom floor.

The adhesive used to fix the flooring contained a large amount of dichloromethane.

An HSE investigation found that contractor T Brown Group Ltd had not implemented any systems or procedures adequately to control the risks to its employees from working in an enclosed space with a substance known to be hazardous to health.

The decision on whether to wear face masks or on what type of respiratory protection should be used was left up to employees.

When Tilcock’s body was found he was wearing a completely ineffectual face mask.

Altro Limited, the flooring company who supplied the adhesive, was found not to have ensured so far as reasonably practicable that the product supplied was safe to use at all times.

T Brown Group Ltd of Ewell, Surrey pleaded guilty to a safety breach and was fined £250,000 and ordered to pay full costs of £23,936.

Altro Limited of Letchworth, Herts also pleaded guilty and was fined £500,000 and ordered to pay full costs of £34,773.

After the hearing, HSE inspector Peter Collingwood said: “This tragic incident which has had a devastating effect on a young family was wholly avoidable.

“It is important that companies have an appreciation of their duties, (whether to its employees or its customers) and have effective systems and procedures in place to ensure that those duties are fulfilled”.