Courtney, who was one of six children, suffered from asthma all her life but it had never been severe.
"I don't want to take away from victims on the frontline, but death by poor air quality needs to be known," said her sister Cherylleigh, 27.
"She was not a severe asthmatic. Mum and Dad are lost but they want other families to read this and take extra steps for asthmatics."
Courtney had hoped to go on to study youth work and spent much of her life working with young people in leadership camps.
"That night the smoke came in so heavy you could not even see the hospital across the road," her sister recalled.
The CEO of Asthma Australia has warned more lives will likely be lost.
"It is something we would like to focus on to better understand the number of people who have lost their lives due to respiratory issues triggered by the bush fires," Michele Goldman said.
Australians have been breathing dangerous levels of smoke and some particles are small enough to enter the lungs.
