Four ambulances and a hazardous area response paramedic called to the Drum Road house at 06:46 BST on Tuesday.
The ambulance service said three people were treated at the scene. The woman’s husband, who is in his 70s, was taken to hospital where he is stable.
Firefighters who took gas readings from inside the house found significant levels of carbon monoxide.
Gas readings were also taken from neighbouring houses and two properties were evacuated for a short time as a precaution.
Neighbours said the couple had lived at the house for decades.
In a statement, police said the woman’s death at a house on Drum Road was “not being treated as suspicious”.