Employers are not liable for exposure to noise below 90dB(A) if the exposure took place before the risks became generally known (around 1990).
The series of cases sometimes called "the Nottinghamshire & Derbyshire Deafness Litigation" has now ended in victory for the employers (by a narrow, 3 to 2 margin) in the Supreme Court. The cases concerned liability of employers in the knitting industry for their employees' hearing loss due to exposure to noise at a lower level than that which had in the past generally been recognised as giving rise to liability.