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Partner Jim Byard looks at the murky issue of diesel engine emissions, the risks of exposure and offers advice to businesses.

As London launches an Ultra Low Emissions Zone and studies show that ‘fresh air’ is harder to come by than we might think, Partner Jim Byard looks at the murky issue of diesel engine emissions, the risks of exposure and offers advice to businesses..

Diesel fumes are a mixture of gas and particulate substances, some of which are known to have carcinogenic and mutagenic properties. Those working in environments where diesel operated heavy vehicles are used, or where vehicles are generating diesel fumes pass by regularly, are likely to be considered ‘at risk’.

The particles in diesel fumes are extremely small and fine - with a diameter of less than 2.5 micro-meters (one thousandth of a millimetre) – which makes them very easy to inhale. The composition of particles can vary depending on the engine size of the vehicle and whether the vehicle is accelerating, decelerating or idling.

Exposure to diesel fumes has been linked to a number of conditions such as lung and bladder cancer, asthma, chronic obstructive pulmonary disease (COPD) and the aggravation of pre-existing respiratory conditions. Recent studies also show an increased risk of cardiovascular disease.

Reports on the adverse health impacts of air pollutions appear on almost a daily basis across the media and are now becoming embedded in the public consciousness.

A study released in 2019 linked air pollution to mental health issues in young people for the first time. It found that 17 year olds living in areas with higher levels of nitrogen oxides – derived from diesel car emissions - had a 70% chance of experiencing psychological issues, such as hearing voices or intense paranoia. These findings are interesting but we must remember that other forms of pollution such as noise, light etc could also be key contributors to mental health issues in young people.

This isn’t the first time a link has been made between air pollution and ill health, as a study last year published in BMJ Open found an association between dementia and exposure to nitrogen dioxide and microscopic particles known as PM2.5. Another study claimed that air pollution could damage placenta in pregnant women. 

This month, London’s ultra-low emission zone (ULEZ), comes into force. Diesel cars manufactured before 2015 are likely to fall foul of the rules, and those emitting an excessive level of emissions will be charged £12.50 in addition to the £11.50 congestion charge. This will be expanded into some residential areas in 2021, and we may see other major cities follow suit.

The most important piece of current legislation applicable to diesel engine exhaust fumes are the COSHH Regulations (2002). These regulations require employers to control exposure to hazardous substances to prevent ill health, and protect employees and others who may be exposed.

So, do diesel engine exhaust fumes constitute a ‘substance(s) hazardous to health’?

In short, yes – so the employer must take action to ‘protect its employees’. 

It’s worth noting that the COSHH Regulations only define a general nuisance dust and fume limit of 5 mg/m3 over an eight hour working day, rather than a specific workplace exposure level for engine exhaust fumes.

The impact of diesel emissions is likely to be felt for several decades both in terms of its impact on health but also in financial terms amongst employers, local authorities and manufacturers.

On one view this appears difficult to reconcile - given the improvements we have seen both in industrial pollution and falling sulphurous emissions largely due to both a decline in the manufacturing industry and improvements to extraction and treatment processes.  

However, the weight of evidence suggests, that the decline in industrial pollution has been replaced or offset by rising levels of nitrogen dioxide and particulate matter which will often impact upon the poorest in society living in the denser conurbations.

Tackling these problems seriously, will come at a cost for the tax payer, the Government and local authorities. In the short to medium term, public transport as a ready alternative to Diesel car use will be placed under increasing strain.

Employers are best advised to follow the COSHH and HSE Guidance and to consider, firstly, where practicable, what alternatives there are to diesel powered engines both in industrial applications and in vehicles. All levels of particulate matter/nitrogen dioxide should be monitored and where exposure cannot be controlled by other means, provide respiratory prot'ection for staff.

Attributing respiratory or other conditions specifically to occupational exposure will remain difficult given the varying factors of environmental pollution and an individual’s smoking habits. For those reasons alone, the issue of diesel emissions is unlikely to become ‘the new asbestos’ for businesses. However, further claims in this space are likely given the growing awareness of the adverse health impacts caused by poor air quality, so employers should do all they can to ensure they clear the air..

Jim Byard is a Partner specialising in occupational disease at national law firm Weightmans LLP

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