Seven people are in a serious condition at the Royal Hobart Hospital suffering from carbon monoxide poisoning after an open charcoal grill was used inside.
Eleven people were taken from the scene on Hillborough Street, South Hobart to the RHH in the early hours of Tuesday morning.
Two adults and five children are in a serious condition. Four other children are being monitored. The children range in age from two months to 17 years.
Police Commissioner Darren Hine said an emergency service response to carbon monoxide poisoning was rare in Tasmania.
Four Ambulance Tasmania units attended a triple zero call about 2.15am and paramedics treated the 11 patients at the scene before transporting them to the RHH.
Hobart Fire Brigade conducted gas monitoring at the scene and recorded carbon monoxide levels at least four to five times above what is regarded as safe.
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The elevated readings were caused by a solid fuel barbecue being used inside for cooking, causing carbon monoxide to build up in the room over several hours.
Firefighters remained on the scene for about an hour ventilating the house and making the scene safe while paramedics attended to the patients.
Acting deputy regional chief Phil Smith said barbecues and grills were designed for outside use and should never be used inside.
"[They] should never be used inside because they need adequate ventilation to allow toxic fumes to escape," he said.
"Cooking that requires the use of solid fuel or gas should only be performed outside unless the appliance is specifically designed to be indoors.
"Carbon monoxide is a flammable and volatile gas, and in addition to the health risks associated with inhaling the toxic gas, there was a real risk of an explosion if the gas was ignited by a spark."
Public Health director Mark Vietch said people should never use things like barbecues inside unless they were installed to take gas away from the burning site.
"Gases can accumulate and spread through a home, they're not detectable and you can't smell them," Dr Vietch said.
He said carbon monoxide poisoning could cause brain damage and death.
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