Noise is one of those topics that most of us have a bit of an idea about when the noise is hazardous or not. But you don’t really know for sure. That is unless you have some sort of system of knowing when it’s exceeded a certain threshold.
There is a bit of a rule of thumb when it comes to managing or identifying noise hazards that people have used over the years.
If you have trouble hearing someone from 1 metre away because of background noise, that’s a good indication that the noise is starting to get close to or exceeding the threshold for when it becomes hazardous.
These days you can use smartphone apps to measure decibels for noise. You never rely on those as our definitive noise assessment because there’s going to be a lot of variability. You can’t really rely on the microphone in a smartphone as your primary identifier of noise. But it does give you a nice idea of when you should proceed to the next level of proper noise identification.
Once you make that call that "yes, this is getting too loud", you need to do an appropriate assessment.
You need to make sure that if you’re doing a proper noise assessment you have use calibrated equipment to identify the actual decibel rating.
If you’re doing a comprehensive assessment you probably should use an expert as well. So, an occupational or industrial hygienist is usually the profession to use.
When you're trying to work out what is excessive noise, you need to know what the decibel rating of that noise is.
The workplace standard for noise is that you’re not allowed to be exposed to more than 85 dB over an 8-hour period.
But what does that mean for shorter periods of exposure?
What this image means is that as the decibel rating goes up the exposure time goes down quite dramatically.
Once you go to 88 decibels, your allowable time goes down to 4 hours. Then at 91 decibels, 2 hours and so on.
You can use a standard risk assessment for managing noise. You will find that you don’t really need to do a comprehensive risk assessment.
If the noise level has been measured and it's been determined as hazardous, you can just skip straight to noise control. This is we know that it's excessive and we know what the appropriate controls are going to be.
When it comes to control, use your hierarchy of controls to make sure that we reduce that noise at the source where appropriate.
You consider the type of equipment that you use and try to either eliminate the use of that equipment.
Alternatively, you can substitute it with a less noisy device.
For example, if you’re using an old, loud piece of equipment and you replace it with a nice new piece of equipment that does the same job but has a much lower noise rating, that’s a big advantage.
The old one might have been working at say, 88 decibels, the new one might be working at 80 decibels. That’s a huge change there because all of a sudden, we don’t require noise control.
There’re some engineering options that you can use. If you don’t replace the equipment, you might use certain sound proofing ideas or mufflers to reduce the impact of the noise.
Administrative controls are going to be mostly looking at exposure times for workers.
If you know that you’ve got something that’s 85 decibels you can have it up to 8 hours. You need to make sure that workers are not working for more than 8 hours in that environment. Therefore, task rotation or moving workers through loud areas is sometimes an administrative control that can be used.
Personal Protective Equipment
But if you've made your equipment as quiet as it can be and you've made sure you're minimising their exposure time, there may still be excessive noise. Some equipment is just loud.
Once that happens, you need to make sure that you’re using personal protective equipment. It’s the bottom of the hierarchy of control but it is really important.
You need to consider the rating the hearing protection has.
You need to make sure that that rating is high enough to reduce the sound level enough so that you’re working in a safe level of noise here.
You have different options as far as the rating is concerned.
There are 5 classes. The higher the class, the higher the rating and the greater the sound level reduction is.
For example, for class 5 equipment that will reduce by 26dB or more.
In another example, for 100 to 105 decibels, you will need to use a class 4 hearing protection device.
Other considerations that you need to take into account when selecting hearing protection are going to be things like hygiene.
Earplugs tend to get a little bit dirty, messy and you’re not going to want to put them in your ears lots of times, so earmuffs tend to work a little bit better in that situation.
Another consideration is eye-ware or glasses. If people are using that and they're using earmuffs, that can reduce the effectiveness. You need to make sure that you are choosing the appropriate hearing protection for people that wear glasses as well.
- You need to identify the sources of noise where it’s becoming a little bit excessive.
- When you’re approaching the noise limit you need to do a comprehensive noise assessment to make sure you know what that noise level actually is.
- You need to make sure is that you control that noise at the source where possible by using substitution or engineering controls.
- When you choose hearing protection as your primary control, you need to make sure you consider the rating and other aspects such as hygiene and just general use and comfort of the hearing protection that you’ve chosen.