Lake Illawarra blaze prompts firies to issue warning

A portable gas camping burner used as an "unconventional heater" was blamed for sparking the fire in the double-storey home on Pur Pur Avenue late Wednesday.

Fire & Rescue NSW Duty Commander Illawarra Andrew Erlik said it was lucky the occupants were awake and watching the football when the fire broke out, as it could have been fatal if they were asleep.

"Never use unconventional means of heating ... they can emit carbon monoxide which can be lethal and cause fatalities," he said.

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Inspector Erlik advised to never use outdoor heaters indoors, nor should you use barbecues or charcoal pits inside the home for heating

While all indoor heaters should have a metre clearance from any other objects.

Fire and Rescue NSW crews from Warrawong and Shellharbour were called to the address at 10:26pm to find the second level alight and battled the blaze for around an hour.

The unit sustained fire, heat and smoke damage to both levels.

NSW Ambulance paramedics attended the incident and treated four people for smoke inhalation.

It's understood two females and the baby were taken to Shellharbour Hospital for further treatment.

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With the onset of winter, Inspector Erlik said he was especially concerned for low-income earners who may be putting themselves at risk - such as the elderly or residents on welfare - and urged them to ask friends, family or charities for assistance.

"It is a concern and probably more widespread through the community than we actually know," he said. "People can't afford electricity so they look for cheaper means of heating."

It comes as a family of five - including an 18-month-old baby girl - were hospitalised in Sydney's southwest on Monday after trying to use barbecue heat beads to warm their home.

The Cabramatta family fell ill and were rushed to hospital for carbon monoxide poisoning.