My question relates to 85dB emanating from an alarm fixed to the inside of the roof next to my left ear that rises and falls in pitch in a confined space such as a cab of a truck. The alarm is activated when the tipping body is raised and in most cases raised for up to 15minutes in a 30/40minute round trip on a 12hr shift. Would this be an acceptable exposure for a safe working procedure as was explained to me as the company's health and safety procedure? Safe or Unsafe for the preservation of Hearing.
I thank you for your time.
Reply from Noise Help:
It's great that you're checking the numbers to make sure that your hearing is kept safe!
Based on your description, your maximum exposure to the 85-decibel alarm would be for six hours during a twelve-hour shift. The occupational limits in Australia allow for eight hours of 85-dB noise during a 24-hour period, so your maximum exposure from this alarm falls under that limit. (Australia's occupational limits
are more conservative than federal occupational limits in the US
, the UK
, and Canada
If you are exposed to any other sounds that are at 85 dB or higher during the same 24-hour period, they would need to be added in to get your total noise exposure. Ideally, during the rest of the time, your ears should not be exposed to sounds louder than 70 dB. Be sure to consider sounds you're exposed to outside of working hours as well, and use hearing protection
as needed. Here's a chart with decibel levels of everyday sounds.
The safety limits are based on what the vast majority of people experience, but different people's ears have different susceptibilities to damage from noise. A small percentage (about 3%) of people who experience daily noise levels at the maximum limit of the legal exposure every day for their entire working lives may sustain slight hearing damage. So nothing is guaranteed safe, but the exposure you describe falls within acceptable legal risk limits.