A picture taken on August 25, 2018 shows the Steigenberger Aqua Magic hotel in Egypt's Red Sea resort of Hurghada where a British couple on holiday died within hours of each other a day before. Engineers have found no fault in the air conditioning unit or any other equipment in the  hotel room, the public prosecutor said today. (Photo by MOHAMED EL-SHAHED / AFP) (Photo by MOHAMED EL-SHAHED/AFP via Getty Images)
CNN  — 

A British couple died from carbon monoxide poisoning while on holiday at a luxury resort in Egypt after the room next door was sprayed with pesticide to kill bed bugs, a coroner has found.

John and Susan Cooper were staying at the Steigenberger Aqua Magic Hotel in the Red Sea resort of Hurghada in August 2018, when the room next to theirs was fumigated with a pesticide, ‘Lambda’, for a bug infestation, the UK’s PA Media reported. In some countries, Lambda is diluted with the substance dichloromethane, which causes the body to metabolize or ingest carbon monoxide.

The fumigated room, which was sealed with masking tape around the door, was connected to theirs with an adjoining door, according to PA.

The married couple returned to their room for the night but were found seriously ill the next day by their daughter. John Cooper, 69, was declared dead in the room, while his wife Susan, 63, died hours later in hospital.

John and Susan Cooper deaths. Kelly Ormerod speaks to the media outside Preston Coroner's Court after the pre-inquest hearing into the deaths of her parents, John and Susan Cooper, who died after becoming ill while staying at the Steigenberger Aqua Magic Hotel in the Red Sea resort of Hurghada on August 21 last year. Picture date: Wednesday May 1, 2019. See PA story INQUEST Egypt. Photo credit should read: Pat Hurst/PA Wire URN:42616564 (Press Association via AP Images)

Dr. James Adelely, senior coroner for the English county of Lancashire, ruled that the deaths were caused by carbon monoxide poisoning as a result of inhaling the vapor from spraying the pesticide which contained dichloromethane, PA reported.

“To this day, our family struggle to comprehend what happened,” the couple’s daughter Kelly Ormerod, who was on holiday with her parents at the time, said in a statement following the inquest.

“It should have never been allowed to happen”.

She said that “nothing would make up for the pain and loss we felt since that day,” adding: “The last few years have been the most traumatic and emotional time for all of us involved.”