‘Sudden Exposure’ NIHL Claims – An Emerging Area of Disease Law? McDonald v Indigo Sun Retail Limited [2021] SC EDIN 20


The All Scotland Personal Injury Court has awarded £241,277 (inclusive of hearing aids, loss of employability and solatium) in damages to a 24-year-old with noise-induced hearing loss (NIHL) and tinnitus.

In this feature article, we review judgment in the case of McDonald v Indigo Sun Retail Limited [2021] SC EDIN 20, which was first publicised by Sarah Ennis, a Solicitor at claimant firm, Digby Brown.[i]


On 12 December 2015, a tanning salon assistant was exposed to noise emissions from a fire alarm (known by management to activate without due cause) in her workplace for a 4-hour period (09:00 to 12:55). There was no fire and no one was aware as to why the alarm was triggered. Throughout her shift, she was instructed to remain in the salon. It was only mid-way through the incident that the manager arrived to muffle the noise with tape and call an engineer (leaving thereafter). For a total of 15 minutes during her shift, she stood on the pavement for auditory relief.

The noise was said to be ‘excessively loud’. It was heard by occupiers of other properties on the opposite side of the street and caused her to converse with customers by shouting. She also found it difficult to concentrate. Ensuing this event, she suffered a severe headache and had a painful ringing sensation in both ears (tinnitus). No prior training or information on how to deal with such an index event had been provided, nor had hearing protection been offered.

After the incident, she was not immediately aware of any hearing loss, but did perceive a ‘muffling effect’, which she attributed to her tinnitus.

This changed on 17 December 2016, when Consultant ENT Surgeon, Ms. Aidah Isa, diagnosed her with bilateral sensorineural hearing loss, having been referred by her GP several months beforehand.

Repeat audiometry, dated 22 February 2017, showed bilateral moderate-to-severe high frequency sensorineural hearing loss and some preservation of hearing in the lower frequencies.

Subsequently, she was referred to Consultant Otolaryngologist, Professor Malcolm Laing, whose working diagnosis was that she had sensitive inner ears and that most of her hearing loss had been caused by the exposure to noise.

In due course, a personal injury action was commenced by the salon worker against her employers.  

This being a post-Enterprise and Regulatory Reform Act 2013 claim, it was asserted that the defender was in breach of its common law duty to take reasonable care for the pursuer’s safety and not to expose her unnecessarily to risk of injury, as informed by Regulations 4, 5, 6 and 7 of the Control of Noise at Work Regulations 2005. There was no direct claim for statutory breach, pursuant to s.69 of the Act, though a reasonable employer would be expected to adhere to such obligations as commensurate with obligations owed under common law [see Gilchrist v Asda Stores Ltd [2015] CSOH 77]. It was also averred that the defender was vicariously liable for its manager’s negligence, which risked the pursuer’s safety.

Essentially, the pursuer’s case was that she had been exposed to conditions that, more likely than not, gave rise to a ‘significant and reasonably foreseeable risk of injury’ and that the history and development of her symptoms were consistent with there being a ‘causal link’ between the noise exposure and the damage sustained.


Acoustic Consultant, Dick Bowdler, assessed the average noise level in the salon to be approximately 87.5 dB pre-muffling and 82.9 dB post-muffling. On a daily noise dose basis (8hr TWA), the pursuer’s calculated noise exposure was 82.3 dB(A) Lep,d – above the ‘lower exposure action value’ of 80 dB(A) Lep,d [see Regulation 4(1)], triggering the defender’s duty to take positive steps to assess the risk of injury, to eliminate or reduce noise to as low a level as is reasonably practicable, and to ensure the availability of hearing protection.

Sheriff Mundy was satisfied that there was a ‘reasonably foreseeable risk of injury’ and that Regulations 5, 6 and 7 had been breached. No suitable and sufficient risk assessment was undertaken, no attempt was made to reduce or eliminate the risk from noise (e.g. by fixing the alarm or deploying an evacuation system) and no personal hearing protectors were afforded.

A ‘small step’ was taken to then establish liability at common law. The defender was also vicariously liable for the manager, who ‘ought reasonably to have instructed the pursuer to leave the premises when it became unsafe for her to remain’, but did not.

N.B. The defender was unsuccessful in advocating instead for a weekly personal noise dose, calculated at 75.8 dB (A) Lep,w – below the ‘lower action exposure value’. With Lep,d accepted as the ‘default position’, the threshold to depart [‘in duly justified circumstances’ – see Article 3(3) of Directive 2003/10/EC on the minimum health and safety requirements, regarding the exposure of workers to the risks arising from physical agents (noise)] was not met. Although the pursuer’s exposure varied markedly from one day to the next (exposure was rare), part-time workers (employed less than 5-days-per-week) were not subjected to the weekly measure and, in any event, no mitigating measures had been taken by the defender to keep noise exposure to a minimum [a precondition of Article 3(3)(b)].


In McDonald, medical evidence caused the ‘greatest difficulty’ in establishing a ‘causal link’.

Consultant Otolaryngologist, William McKerrow, examined the pursuer on 12 September 2018 and confirmed earlier diagnoses, but his medical report, which referred to the Guidelines on the Diagnosis of Noise Induced Hearing Loss for Medico-Legal Purposes by Coles, Lutman and Buffin (2000), acknowledged that not all of the requirements were met.

Whilst he claimed that R1 (high frequency hearing impairment) and R2 (noise exposure) were substantiated, he admitted that R3 (audiometric configuration) was ‘not classical’ for NIHL. Indeed, there was only evidence of notching at 6 kHz in the left ear. Regardless, Mr. McKerrow maintained that the absence of a notch or bulge in the right ear did not preclude the presence of NIHL having an atypical audiometric configuration, albeit he omitted to mention that this eventuality would generally fall below the balance of probabilities.

On cross-examination, the pursuer’s expert was forced to concede that, not only was R3 not satisfied, but also R2(a), seeing that the pursuer’s noise dose of 82.3 dB(A) Lep,d could not lead to a cumulative exposure of at least 100 dB(A) NIL. This irregularity was likely instigated by the fact that his report pre-dated the engineer’s report on noise levels.

Fundamentally, Mr. McKerrow still insisted that the pursuer’s hearing loss was attributable to the fire alarm, on the basis that ‘mathematical criteria were not the only … [variables] … to be taken into account’. The pursuer’s history, the circumstances surrounding the onset of her symptoms and her credibility were also treated as important, to such a degree that the expert concluded, with 95% probability, that the fire alarm caused her hearing loss. Before the pursuer’s exposure, aged 20, she demonstrated no tinnitus or hearing difficulties. Immediately after the exposure, she did.

On the other hand, the defender’s medical expert, Iain Swan, sought to discredit a diagnosis of NIHL without making a single reference to the CLB Guidelines. He considered that the pursuer was affected by progressive congenital hearing loss, unconnected to noise exposure.

The Consultant Otologist offered several theories to explain why the pursuer had developed high frequency sensorineural hearing loss for non-noise-related reasons, but many of the accusations posited, e.g. that the pursuer delayed seeking medical advice, that the pursuer had a ‘mild speech impediment’ consistent with childhood hearing impairment and that the pursuer was ‘unlikely’ to develop permanent deafness from the alleged exposure period, were ‘unsound’ and deserved to have ‘little weight’ attached.

What is more, the defender criticised Mr. McKerrow for his erroneous application of the Coles Paper, which called into question his ‘independence’ and ‘impartiality’ as an expert witness – a ‘deliberate attempt to mislead the court’? It was hoped that this fact could not be overlooked and, following Kennedy v Cordia (Services) LLP [2016] UKSC 6, Mr. McKerrow’s evidence would be excluded as inadmissible.

Again, though, the defender’s submissions were not favoured by the Court. On the whole, the pursuer’s expert exhibited his ‘many years of expertise in the field’ in a ‘satisfactory manner’ and, notwithstanding numerous concessions, his evidence was not judged to have been ‘fatally undermined’ by the opposing party.

In the round, Sheriff Mundy was persuaded that a ‘legitimate inference’ could be drawn that the pursuer’s exposure to noise, on 12 December 2015, was ‘the cause of her hearing loss and tinnitus and not merely the occasion for it’. He could find ‘no other credible explanation’ to account for the pursuer’s condition and the fact that Mr. Bowdler had not dismissed the prospect of sub-85 dB(A) Lep,d exposures causing NIHL as ‘insignificant’ compounded the pursuer’s argument.

N.B. It is clear from the above section that the pursuer was put to proof on causation and did so successfully.

In fact, the pursuer did attempt to reverse the burden of proof onto the defender by testing residual uncertainty over the full impact of the 2013 Act.

On this particular issue, Sheriff Mundy found that there is no onus upon the defender to disprove causation unless a breach of statutory duty arises and points prima facie to a ‘causal link’ – see Goldscheider v Royal Opera House Covent Garden Foundation [2018] EWHC 687 (QB).

The index case was not an action in which a prima facie case on causation could succeed. Applying the 3-stage test devised by Lord Reid, in Gardiner v Motherwell Machinery and Scrap Co. Ltd 1961 SC (HL) 1, alongside Mr. McKerrow’s concessions on R2(a) and R3, it could not be deduced that the pursuer’s exposure to noise from the fire alarm was ‘of itself’ likely to cause the disease complained of (the 3rd element of the Gardiner test).

In summation, Sheriff Mundy rationalised his findings on liability, at paragraph 119:

‘… the level of noise to which the pursuer was exposed was such as represented a reasonably foreseeable risk of injury in the form of tinnitus and hearing loss. While it cannot be established that it was at or above 85 dB(A), it was nonetheless above the “lower exposure action value” of 80 Db(A) set forth in regulation 4(1) of the 2005 Regulations in relation to which action required to be taken as previously outlined. Furthermore, while the level of noise was not such as of itself to make it more probable than not that damage would result, in light of the evidence in this case, and in particular the development by the pursuer of symptoms which are consistent with damage being caused on 12 December 2015, I have concluded as a matter of fact that it is more likely than not that the damage was caused by the exposure to noise and that the development was not mere coincidence. In other words, the pursuer has discharged the onus upon her to prove causation by the civil standard. The very risk that the regulations were designed to avoid eventuated and, as indicated, it is my view that the obligations in the regulations founded upon are within the compass of the employer’s duty to take reasonable care at common law’.

Full text judgment can be accessed here.


Ms. Ennis, of Digby Brown, described McDonald as a ‘particularly noteworthy’ case, which is perhaps an understatement.

She recognises the fact that ‘traditional’ NIHL or ‘industrial deafness’ claims ordinarily involve prolonged periods of exposure to excessive noise, but are becoming less common, due to employers’ growing awareness of the associated health risks. She does so as a means to subtly introduce McDonald-like cases, i.e. those concerning ‘sudden’ exposures, as an emerging area of law.

Of course, the legitimacy of this implication is necessarily dependent upon the whether the correct decision was made in the present Court ruling.

Interestingly, the Digby Brown article goes no further than to say that Mr. McKerrow’s methodology (use of Coles) was ‘criticised’ by the defender without consequence.

In reality, it is conceivable that the pursuer won her case because (1) there was a distinct lack of conflicting evidence adduced by Mr. Swan, (2) a copy of the CLB Guidelines was not produced in Court and/or (3) the individual facts of McDonald were distinguishable from most NIHL cases where there is a gradual development of the disease with more than one potential cause. Alternatively, Sheriff Mundy arrived at the wrong result.

What if, moving forwards, pursuers in Scotland and claimants in England and Wales are able to rely on McDonald as a binding authority? Might it be possible, on the facts, to circumvent Coles requirements that are not fully met and still establish a nexus between relatively short-term exposures and rapid development of sensorineural NIHL?

Defendants and defenders should be vigilant to opponents who argue, on the proviso that breach can be established and the risk of injury is foreseeable, that it is ‘wholly irrelevant in law that the 2005 [Noise] Regulations envisaged long-term hearing loss rather than an immediate onset of symptoms in the manner sustained by the pursuer[/claimant] – following Lord Reid in Hughes v Lord Advocate [1963] UKHL 8:

‘This accident was caused by a known source at danger, but caused in a way which could not have been foreseen, and, in my judgment, that affords no defence’.


[i] Sarah Ennis, ‘All Scotland Personal Injury Court awards substantial damages to a pursuer exposed to noise from a fire alarm’ (13 April 2021 Digby Brown) <https://s3.amazonaws.com/documents.lexology.com/ef2f3975-e73b-457e-ac36-589a33677f6e.pdf?AWSAccessKeyId=AKIAVYILUYJ754JTDY6T&Expires=1622811315&Signature=wo8qc%2BsdSrkbe%2FfAPd9NP3nx%2FXk%3D> accessed 4 June 2021.