Is white noise safe to use in my nursery?

How old is your baby?

The use of any noise/music is not a known risk for Sudden Unexpected Death in Infancy (SUDI)
Red Nose does not have any specific information about use of white noise machines.
There have been some concerns expressed in relation to safety, particularly related to batteries in any soft toy that my have the playing device in the soft toy.
Are the batteries in the machine safely secured?
There are Mandatory Standards from Product Safety Australia about storage/use of button batteries.
https://www.productsafety.gov.au/products/electronics-technology/button-batteries

Ensure any soft toys are not placed in the sleep environment of baby less than 7 months of age.
Ensure large or multiple soft toys are not in baby’s sleep space.

Keep the cot free of large soft toys, pillows, bumpers, activity centres and anything else that could be ‘stacked’ to assist a young child/toddler to climb out of the cot.
https://rednose.org.au/article/can-my-baby-have-a-soft-toy