Tests have revealed the amount of Carbon Monoxide recorded in a home where three people died was 20 times the fatal dose.
The bodies of John Cook, his wife Audrey and their daughter Maureen were found in a static home at the Tremarle Park in Camborne on Saturday.
Today Cornwall Fire and Rescue Service said they would have been 'unconscious within minutes'.
All homes at the park use gas for heating and cooking. Inspectors are examining the family's cooker.
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A light breeze winds across the region, with clouds and rainy spells. There may be mist or fog in places.
Tonight will see light winds across the region, accompanied by cloudy skies, outbreaks of rain and mist and fog spreading north overnight.
Campaigners fighting the abuse chose Bristol bus station to try to educate the public on a growing problem.