The figures compared with just 10% of males of the same age not exposed to occupational noise, the inspectorate said in its latest safety alert.
“The risk of noise-induced hearing loss is high for mine workers as a lot of mining equipment is large and noisy,” it said.
“Long work shifts result in prolonged noise exposure with insufficient time for sensitive parts of the ear to recover before the next shift.
“NIHL gradually worsens with continuing exposure to noise and most workers are unaware of their hearing loss until it becomes obvious to other people and by then the hearing loss is severe.”
The inspectorate recommends employers should develop effective hearing conservation programs for their workers which involve noise level monitoring, training and education and measures to control noise.
Workers should also remain vigilant to exposure to noise and ensure that ear plugs are properly inserted to provide adequate protection to the ears.
“As a rough guide, if you must raise your voice to communicate with someone standing a metre away, the noise level is almost certainly too high and may be damaging your hearing,” it said.
“Hearing protection, which can be plugs or earmuffs (both provide adequate protection for most noisy situations if correctly worn), should be used until other measures can be considered.
“While hearing loss is permanent, it will not worsen over time if further exposure to excessive noise is avoided.
“Therefore it is important that everyone, even those with some hearing loss already, take all possible care to avoid excessive noise exposure.”
The inspectorate said ear plugs couldn’t provide sufficient protection if only partially inserted so it was important they were inserted correctly.
“Firstly, to prevent ear infection, ensure that hands are clean to avoid introducing dirt and grease into the ear canal,” it said.
“Then, roll the plug into a thinner cylinder and with the opposite arm over the top of the head, pull the ear backwards to straighten the ear canal.
“Insert the rolled plug well into the ear canal and hold in place for 30 seconds.
“The plug will expand to its former size, forming an effective seal. Repeat with the opposite side. Only the tip of the plug should be visible.”