How can employers demonstrate due diligence for diesel fume exposure?

Employers demonstrate due diligence by showing that diesel exhaust exposure has been properly identified, assessed, and managed rather than ignored or assumed to be “low risk.” In practice, this starts with recognising diesel exhaust as a hazardous substance under COSHH and acknowledging that modern enforcement treats it as a serious health issue, not a nuisance exposure.

A key step is commissioning diesel exhaust exposure monitoring where diesel-powered vehicles, plant, or generators are used indoors or in partially enclosed areas. Monitoring provides objective evidence of exposure levels rather than relying on judgement alone. Alongside this, employers should document risk assessments, control measures (such as ventilation, engine upgrades, or operational changes), and staff training.

Regular reviews are also important. If work activities, engine types, or shift patterns change, exposure assumptions may no longer be valid. Keeping records of reassessments shows an ongoing commitment rather than a one-off exercise.

From an enforcement perspective, regulators such as the Health and Safety Executive look for evidence that risks were anticipated and managed proportionately. Having monitoring data, written assessments, and clear actions taken off the back of results is often what separates due diligence from reactive compliance.