Hundreds of revellers at a swingers’ club in Germany were forced to evacuate after a carbon monoxide alarm went off.
Many guests at the party in the western town of Hattingen had to leave the premises in bathrobes.
Several said they did not feel well after the alarm went off late on Saturday night, authorities said.
Carbon monoxide, a poisonous gas which has no odour, taste or colour, can kill humans if they are exposed to it in large enough quantities.
There are around 60 deaths from accidental carbon monoxide poisoning in England and Wales each year.
Firefighters in the town of Hattingen, between Dortmund and Duesseldorf in North Rhine-Westphalia, told the dpa news agency around 300 swingers were brought to safety.
The swingers were taken on buses to be examined by first aid workers.
Around 10 who complained they felt unwell and required treatment.
The fire department said no dangerous levels of carbon monoxide were detected once they had arrived.
Around 160 emergency workers were involved in total.
Carbon monoxide travels into the bloodstream after it is inhaled where it combines with haemoglobin, the element of red blood cells which transports oxygen around the body, to form carboxyhaemoglobin.
When this occurs haemoglobin can no longer move oxygen around the blood, potentially leading to death.
Dozens of carbon monoxide alarms sold over Amazon and eBay were pulled off the shelves after they flunked safety tests last year.
Four alarms available for sale on the retail websites were not able to notice the gas, an investigation by Which? found.
Additional reporting by Associated Press
