A 59-year Roscommon woman died from carbon monoxide poisoning earlier this year.
An inquest heard she had fatal levels of the colourless and odourless gas in her bloodstream when her body was discovered in July.
Roscommon Coroner's court heard the woman lived alone and rarely left her home.
Her sister helped with shopping and she told the inquest the only time windows would be open was when the house was being cleaned to allow it to dry out.
The last contact with the woman was on the 14th of July, when she was described as being in good spirits, following a phone conversation.
However, efforts to speak to her three days later were unsuccessful - despite repeated attempts - and the woman's sister and husband went to her home to check in on her.
When they arrived, lights were on and so was the television and the curtains were closed.
They let themselves in and found her body with dried blood under her head but no visible sign of any physical injuries.
However, her face and hands were discoloured.
The range in the kitchen was still warm and the sofa was pushed up beside it.
Consultant pathologist Dr Helen Inglesby revealed the post mortem showed no sign of fractures or trauma. However, her blood had a fatal 59% saturation level of carbon monoxide.
Levels of between 50% and 70% are thought to be fatal.
The Doctor was also asked how long the carbon monoxide may have been present and she suggested it can happen over a period of hours and that people often have no symptoms but just feel a little sick.
The inquest heard the woman only burned coal in her range and she had a habit of opening it up for fuel, but leaving the top opening to the firebox open and smoke subsequently escaping into the room.
Her date of death was returned as the 14th of July and the cause was deemed carbon monoxide poisoning.
An open verdict was returned as there was insufficient evidence for any other verdict.
Sympathies were expressed to her family.
