Safe design is about integrating hazard identification and risk assessment methods early in the design process to eliminate or minimise risks of injury throughout the life of the product (including buildings, structures, equipment and vehicles) being designed.
The model WHS Regulations, define the exposure standard for long term exposure to noise as the amount of sound energy, that is equivalent to a steady noise level of 85 decibels over an 8 hour shift. Whether this is exceeded depends on the level of noise involved and how long workers are exposed to it.
Safe Work Australia does not provide legal advice on the operation of the model Work Health and Safety laws. You must contact your work health and safety authority in your state or territory. PPE is one of the least effective safety control measures: you should not rely on PPE as a hazard control.