An 84-year-old man and two women have been treated for the possible side effects of breathing in carbon monoxide from a faulty boiler at a house in Littlebury.
Two fire crews were called to a detached cottage in Walden Road on Wednesday morning after the ground floor filled with smoke and the boiler produced noxious fumes.
The man and the two women, who were aged 21 and 25, were all treated at the scene and are now fully recovering.
An Essex County Fire and Rescue Service (ECFRS) spokesman said: “When crews arrived the ground floor of the property was smoke logged. They located the source of the smoke to a boiler on the ground floor.
“Crews administered oxygen therapy and first aid and the casualties were then placed in the care of the ambulance service.”
Carbon monoxide is invisible to the naked eye and has no taste or smell so is almost impossible to detect without specific devices.
The dangers are so great that ECFRS has issued safety advice on many occasions.
The spokesman added: “Carbon monoxide (CO) poisoning is a serious threat that people need to be aware of. Educating people on the dangers can significantly reduce the health risk as well as save lives.
“Although everyone needs to be aware, older people are more susceptible than others.
“It is important that gas appliances are serviced by competent engineers.”
The signs to look out for are yellow or brown staining around or on appliances, pilot lights frequently blowing out, increased condensation inside windows and yellow rather than blue flames.
Low levels of carbon monoxide poisoning can be confused with flu symptoms, food poisoning or other illnesses and can have a long-term health risk if left unattended.
Among the symptoms are a shortness of breath, mild nausea and headaches. Carbon monoxide alarms are readily available from most DIY stores and should be fitted in accordance with the manufacturer’s instructions.