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Diesel Fumes

AWARE19/10/2012
Disease Aware Issue 1

Although diesel engine fumes were defined by IARC as probably carcinogenic to humans (group 2A) in 1989, an advisory group had repeatedly called for a re-evaluation since 1998. This reclassification elevates the status of diesel fumes to the same potentially deadly category as asbestos, arsenic and tobacco. This conclusion was reached on the basis of research showing that regular exposure to diesel fumes is as likely to cause cancer as passive smoking.

The experts were unanimous in their conclusions, which were based on 'compelling' scientific evidence’. They urged people to reduce exposure to diesel fumes as much as possible. The evidence of harmful health effects from exposure to diesel fumes, particularly for people exposed to high levels in the course of their employment, has been accumulating for many years. Even so, the overall number of lung cancers caused by diesel fumes is likely to be a fraction of those caused by smoking tobacco.

Is this a case of improved under-standing of the effects of diesel fumes or has something changed?

Potential reasons for the apparent increase in harmful health effects from diesel fumes were postulated by IARC, including: (i) the popularity of diesel cars in the developed world where tax advantages have encouraged technological advances and more demand; and (ii) the exposure of large populations on a worldwide basis to diesel exhaust in everyday life, whether through employment or environmental factors.

The diesel engine, refinery and emissions control technology industries have already invested heavily in research into strategies to reduce emissions based on ultra-low sulphur diesel fuel and virtually zero emissions for nitrogen oxides, hydro-carbons and particulate matter. IARC said it had considered these recent advances but added that further research was needed to understand how they might translate into health effects. Obviously there will be a time lag in noticing any improvements to health in that existing fuels and vehicles/equipment without modifications will take many years to be replaced.

Which categories of employees are at risk?

Most directly at risk will be diesel mechanics and those working in the proximity of processes and/or machinery producing diesel exhaust e.g. power plants, hydraulics systems, locomotives and farming equipment etc. Other risks to health from exposure to diesel fumes: where exposure is short-term, the health risks are usually minimal whereas long term exposure can cause serious complications that may be fatal. The symptoms associated with longer term exposure to diesel fumes cover a wide range of effects including:

  • Bodily irritation: including eye or respiratory tract inflammations: these are typically mild and short lived
  • Dermatitis: characterised by reddened, swollen and itchy skin: those already sensitised to these substances may experience an outbreak or exacerbation of dermatitis upon further exposure
  • Shortness of breath and coughing: if exposure continues for long enough, the effects can become chronic and lead to more serious health issues
  • Lung disease, heart disease and other immune system problems: all of these conditions have been implicated with varying degrees of proof, with lengthy exposures to diesel fumes.

The reduction of risk

The control of risk in respect of exposure to diesel fumes is governed by the Control of Substances Hazardous to Health Regulations 2002 (as amended) (COSHH) which requires employers to make suitable and sufficient assessments of the risks to health in the context of exposure to diesel fumes.

Having identified a risk the employer should then take the necessary steps to prevent or adequately control the exposure in the workplace. Where exposure cannot be prevented, the employer must consider a combination of control measures including air extraction fans, tailpipe exhaust extraction systems, and the use of filters attached to tailpipes and catalytic converters.

More common sense control measures would include turning off engines when not required, keeping doors and windows open where practicable, installing air vents in the walls and ceilings, job rotation and providing suitable personal protective equipment (suitable gloves should be worn when handling hot and cold diesel fuel). The employer should also ensure that employees are provided with necessary information on the risks of exposure to diesel fumes and any personal protective equipment that is required to be used.

Threshold levels

Despite an abundance of leaflets and cautionary warnings about the risks associated with exposure to diesel fumes, there exists very little information to suggest what a ‘safe’ threshold level for exposure might be or indeed, if such levels are even measurable in the environments in which exposure is likely to occur. Employers must work on the basis that any regular exposure to diesel fumes constitutes a risk, and take precautions.

Legal implications

English law requires causation to be established on a ‘but for’ basis i.e. but for the tort (the exposure to diesel fumes), the claimant would probably not have suffered the injury complained of: in other words, that the relevant exposure caused or materially contributed to the development of the lung cancer. Difficulties can arise: (i) where there is more than one potential cause for the condition in question and only one of those potential causes arises from the negligence of the defendant (which certainly applies to the aetiology of lung cancer); and (ii) where the causative association is weak.

The effect of the IARC reclassification in respect of diesel fumes will be to enable any claimant, who is able to prove relevant exposure over a sufficiently long period of time, and who subsequently develops lung cancer, to establish: (i) that the exposure was capable of causing the lung cancer; and that: (ii) absent any competing and more compelling causes e.g. smoking, that the exposure did in fact cause the lung cancer on a balance of probabilities. This raises the prospect of some very interesting causation arguments, including having to address the issue of the ‘multiplication of risk factors’, e.g. when a claimant has been exposed to more than one significant risk factor (say exposure to diesel fumes and smoking), each factor which alone would have been sufficient to explain the cause of his lung cancer, but which together have acted to disproportionately increase the overall level of risk. Complications such as this will not arise where there are no obvious alternative candidates for causation and these cases should be more straightforward, assuming that exposure and breach of duty can be established.

Will the reclassification give rise to more litigation?

The WHO has calculated that 71% of lung cancers on a worldwide basis are associated with smoking and it remains to be seen how exposures to diesel fumes might be factored into these causation figures. By way of contrast in 2010 there were 2,285 deaths from mesothelioma in the UK. On the basis that it will now be much easier to prove the causation of lung cancer where a claimant can establish exposure to diesel fumes on a regular and prolonged basis, it probably won’t be too long before lawyers looking to discover new avenues for litigation identify the possibilities created by this new development.