Introduced in 2019, it is now mandatory to exhaust your rangehood to atmosphere.
Kitchen (Rangehood) exhaust removes steam, smoke, and cooking odours from your home as well as removing grease particles that would otherwise build up on your walls and cabinetry.
The Building Code of Australia (BCA) enforces Australian Standard AS 1668.2-2012, which states a minimum extraction capacity of 50 litres per second for residential kitchens. Many designs are produced requiring a level closer to 90 litres per second.