Family narrowly avoids fatal disaster after using a barbecue as a heater in Sydney unit

A Sydney family have narrowly escaped with their lives after suffering carbon monoxide poisoning from using an outdoor barbecue as an indoor heater.

Firefighters said the family had brought a charcoal barbecue inside from their balcony in an effort to stay warm at their unit on Wentworthville Avenue in Wentworthville overnight.

But the family-of-five were overcome with carbon monoxide fumes more than four times the dangerous limit.

Firefighters rushed to the scene and found three people unconscious and moved the family onto the balcony to begin medical treatment about 4.15am today.

Paramedics then arrived and took three adults and one child to hospital for further treatment while firefighters ventilated the unit.

Carbon monoxide is a colourless, tasteless and odourless gas that can overwhelm and cause death without its victims being aware of the impact.

The near-fatal accident has sparked a public warning.

"There's nowhere for the poisonous fumes to go if they build up indoors," Fire and Rescue NSW Commissioner Jeremy Fewtrell said.

"Using charcoal bead cookers, BBQ's and outdoor heaters inside creates an extreme risk to you and your family.

"We understand that as the weather is particularly cold at the moment, families may be tempted to use alternative heating sources, but these types of items will risk the lives of you and your family rather than making you warm and comfortable in your homes."

Fire crews will return to the unit block today to provide safety advice to neighbours.