It has been known for decades that it is virtually impossible to guarantee adequate protection from hearing protectors at noise levels above c 95dB(A). Consequently, it should not have been news that research by the Health and Safety Laboratory (report RR720) proved that the common assumption that PPE is a reliable “solution” to hearing damage risk problems is simply untrue. This assumption has left many personnel at risk and companies are open to claims if their hearing conservation policy is based on PPE use. Some of the key findings of the research are:-
The inadequacy of PPE performance in many real-world situations is also born out by the continuing tidal wave of hearing damage claims of £400 million in one year (2014 - IFA UK deafness working party), despite (or even because of) the over-reliance on PPE without understanding the performance limitations away from the lab. This also brings into sharp focus the need to reduce noise levels to reduce risk, even when the levels cannot be reduced to below 85dB(A).
As a rule of thumb, provided effective (and time-consuming) management systems are in place, most good quality PPE can be made to work up to noise levels of around 95dB(A). Above this level, it becomes increasingly difficult to guarantee sufficient protection and above c 100dB(A) it becomes virtually impossible.
The key (and very often missing) factors necessary to improve real world protection are:-
In conjunction with the above, most organisations can cut risk by 50% - 90% at little or no cost (or even at a profit) by introducing very low-cost engineering noise control measures to reduce noise to levels at which PPE can be made to work. For example, reducing noise by 3dB from 97dB(A) down to 94dB(A) halves the risk (and PPE is more effective). Reduce the noise by 6dB and the risk falls by 75%.
There is more on the topic of self-financing noise control, including a White paper here.