Diesel fumes and their risks are a source of great interest in the claims market currently, with interest in the class action against Volkswagen and the 'dieselgate' scandal, along with concerns about environmental exposure to harmful levels of air pollution in major cities such as London.

Earlier this year, Volkswagen's subsidiary in the United States resolved the first claim set to go to trial over the misleading sales of vehicles, and the October 26 deadline for English and Welsh consumers to lodge their claim for compensation looms large.

In the background to these headlines, is there a risk that the personal injury claims market will be polluted by significant numbers of diesel exposure claims?

There are currently steady numbers of claims from individuals who allege that they have suffered personal injury as a result of occupational exposure from diesel fumes.

As claims steadily increase, claimant representatives will be eager to exploit examples of successful outcomes and bring further claims. A well-publicised success could lead to an undercurrent becoming a tidal wave of claims.

We are therefore pleased to report that Clyde & Co has successfully defended a claim alleging that the Claimant's occupational exposure to diesel fumes and ammonia caused asthma. Our success demonstrates the scope there is to defend claims of this nature and that they should be rigorously assessed.


The Claimant alleged that he was exposed to diesel fumes in his role as a vehicle recovery agent over a 6 year period, which caused him to develop occupational asthma. The Claimant also alleged that ammonia was added to the diesel and that this was also causative of his asthma.

The Claimant alleged that our clients (the Defendants) had breached of the Control of Substances Hazardous to Health Regulations, failed to prevent his exposure to hazardous substances and provide personal protective equipment, as well as common law allegations of a failure to provide a safe place and system of work. The Claimant sought damages in excess of £300,000.

The claim was defended in both on liability and causation, with the Defendants responding that a safe system of work was in place throughout the Claimant's employment. The roadside vehicles were inspected and serviced periodically, then replaced every 4 to 5 years. An aqueous solution of urea known as AdBlue was also added to the exhaust system of the recovery vehicles (in line with standards) breaking down oxides of nitrogen into water, carbon dioxide and ammonia, ensuring that the vehicles would run clean.

Medical Evidence

Both parties obtained medical evidence from a Chest Physician, with the Claimant's expert supporting the Claimant's allegations. The Defendants' medical expert noted the diagnosis of asthma was made following Mannitol Provocation Tests, yet the Claimant's symptoms were not alleviated by high doses of inhaled steroids as expected. The expert concluded that the Claimant's breathlessness was in fact typical of hyperventilation syndrome.

Non-Medical Evidence

Both parties obtained evidence from an Occupational Hygienist. The Defendants' expert was firmly of the opinion that the Claimant's exposure was insufficient to have resulted in his alleged illness.

The experts confirmed that there is no occupational exposure limit for diesel engine exhaust fumes in the UK.

Moreover, the Defendants' expert was of the view that in the context of the Claimant's allegations, the Claimant's alleged exposure cannot be interpreted as a substantial concentration of diesel exhaust fumes. Whilst there is an occupational exposure limit for ammonia, the expert noted that the Claimant's exposure was likely to have been low, and much lower than the occupational exposure limit.

The Claimant's expert agreed that the gaseous components of diesel were generally found at low levels in the workplace. Addressing the use of AdBlue, the Claimant's expert stated the by-products of water, ammonia and carbon dioxide were relatively harmless.


We were firmly of the view that the evidence of both non-medical experts supported a denial of liability and causation, and that our medical expert had offered a credible alternative hypothesis for any medical symptoms the Claimant was experiencing.

We were therefore firmly of the view that the claim should be defended through to Trial. No concessions were made to the Claimant, who then discontinued his claim, representing savings to our insurer client in excess of £300,000.

What can we learn?

  • As awareness about the potential dangers of exposure to diesel fumes increase, it is anticipated that there will be more claims of this nature, albeit there is no current indication of a dramatic increase in claims of this nature currently. Nonetheless, as stated previously, there should not be complacency in handling these matters, at the risk of claimant successes leading to the floodgates opening for similar claims.
  • Whilst there is literature and warnings about the risks associated with exposure to diesel fumes, there is at present very little information to provide an indication as to an established safe threshold level. Notably there is no occupational exposure limit for diesel engine exhaust fumes in the UK. It therefore follows that the best practice will be for employers to put in place sensible safeguards in circumstances where there may be frequent exposure to diesel engine exhaust fumes, and for insurers to ensure that policyholders have these safeguards in place.
  • The Claimant's allegation that excessive ammonia had caused/exacerbated his illness was perhaps led by the knowledge that there are occupational limits on exposure to this material. In the absence of our expert evidence to refute this allegation, this may have presented a credible argument for the Claimant. Any further allegations of this nature will need to be closer examined and dealt with appropriately.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.