There was a real risk of ash dropping onto the bed, or the person "nodding off".
It was also a reminder to have working smoke alarms. Miss Borell had only moved into the house two days before the fire, and didn't have any smoke alarms.
Specialist fire investigator Stu Craddock told the inquest that the fire had been recorded as undetermined but that there was only one possible cause of the fire identified - that she may have been smoking in bed and accidentally dropped the cigarette onto the bed then fallen asleep.
Mr Craddock said fire crews were confronted with a "well-involved" fire when they went into the house and said by the time they found Miss Borell's body, lying face down partially in the wardrobe, it was obvious she had died.
He said others in the house had tried to extinguish the fire in the bedroom with pots of water, but were unsuccessful.
Detective Constable Russell Bell said toxicology results showed there was a 20 per cent saturation of carbon monoxide in Miss Borell's blood.
The cause of death was established as smoke inhalation and extensive burns.
Miss Borell's partner and two other family members were at the hearing, but did not speak.
Dr Bain reserved his findings.