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Diesel Engine Exhaust Emissions - The Complete Guide
Posted 15th January 2020

Diesel Engine Exhaust Emissions (DEEE's) contain a complex mixture of gases, vapours, liquid aerosols and particulate substances. You may be exposed to diesel fumes if you work where diesel operated heavy vehicles are being used, or where motor vehicles are generating diesel fumes such as when coming into and out of car parks or when passing toll booths. You may also be exposed to diesel fumes if you are working in tunnels or on construction sites where diesel operated stationary power sources are being used.


Common side effects of diesel exhaust exposure include irritation of the nose and eyes, lung function changes, respiratory changes, headache, fatigue and nausea. Chronic exposures are associated with cough, sputum production and lung function decrements. There are also observations supporting the hypothesis that diesel exhaust fumes are an important factor contributing to the allergy pandemic and hence increasing general sensitisation to other substances.


Diesel emmissions as a whole do not have specific workplace exposure limits (WEL's) and therefore any exposure assessment monitoring strategy must cover the main constituents that are know to have adverse effects on health. 

Typical chemical constitutes generated from engine emmissions and there exposure limits (WEL's) are as follows:


  • Carbon Soot (4mg/m3)
  • Carbon monoxide (23mg/m3)
  • Carbon dioxide (9150 mg/m3)
  • Oxides of nitrogen (NO 2.5 mg/m3, NO2 0.96mg/m3)
  • Formaldehyde, Acrolein,Glutaldehyde, Acetaldehyde (2.5mg/m3, 0.05mg/m3, 0.2mg/m3, 37mg/m3)
  • Benzene, Toulene, Ethyl Benzene, Xylene (3.25mg/m3, 191mg/m3, 441mg/m3, 220mg/m3)
  • Polycyclic aromatic hydrocarbons (No WEL's assigned)


Exhaust emissions from diesel engines are usually more visible than those emitted from petrol engines because they contain over ten times more soot. In general, diesel engines produce less carbon monoxide than petrol engines but more oxides of nitrogen, sulphur oxides, aldehydes and particulate matter.


The soot particulates in DEEEs have hundreds of organic substances adsorbed onto their surface, some of which are potentially more harmful to health than others. The soot content in DEEEs varies from 60% to 80% depending on the fuel used and the type and condition of the engine.



Under the Control of Substances Hazardous to Health Regulations (COSHH), you should make a suitable and sufficient assessment of the risks to health if you are exposed to diesel fumes. You should then take the necessary steps to prevent or adequately control exposure in the workplace. Where exposure cannot be prevented, you will need to consider the use of a combination of specific control measures including:


  • workplace air extraction fans;
  • tailpipe exhaust extraction systems;
  • the use of filters attached to tailpipes;

    and more general control measures such as:
  • turning off engines when not required;
  • keeping doors and windows open where practicable;
  • installing air vents in the walls and ceiling;
  • job rotation;


You should only provide respiratory protective equipment as a last resort when other means of control are not suitable.

The presence of soot on the walls and other surfaces or a visible haze in your workplace is a useful indicator that diesel fumes are not being adequately controlled. In addition to the control measures described in the preceding paragraphs, you should also ensure that:


  • any engineering controls used are properly maintained and checked regularly;
  • where necessary, exposure to diesel fumes is monitored (see following section);
  • you are provided with the necessary information on the risks of exposure to diesel fumes;
  • you are provided with instruction and training on the safe use of the control measures and any personal protective equipment that you are using.


Monitoring for exposure to DEEEs in the workplace (COSHH regulation 10)

Under regulation 10 of COSHH, monitoring at the workplace may be required for the following reasons:


  1. To determine if there is a failure or deterioration of the control measures which could result in an obvious health effect, i.e irritancy from exposure to DEEEs;
  2. To determine whether any workplace exposure limit (WEL) or any in-house working standard has been exceeded; and
  3. When necessary to check the effectiveness of a control measure provided, eg particulate filter, LEV and/or general ventilation.

The health risk assessment will help you decide if it is necessary to carry out monitoring, for example, to judge the effectiveness of controls. A suitable monitoring strategy, as determined by a competent person such as an occupational hygienist, will indicate whether personal monitoring, fixed placed (static) monitoring, or both are required. It will show which site(s) require monitoring, when and how often, and which sampling and analytical methods would be appropriate.

You may need to carry out personal monitoring to determine the extent of inhalation exposure to DEEEs, and hence the level of risk. Personal monitoring samples should be collected in the breathing zone of the employees. Such samples should be collected where there is a significant potential for exposure during their working shift and include peak exposures, eg while repairing or testing/maintaining an engine, while driving a fork-lift truck or during lashing in ro-ro ferries.


The duration of sampling depends on the workplace situation, such as the nature of the work and the type of monitoring. However, to collect sufficient material from the workplace air and determine the time-weighted average (TWA) exposure, sampling periods will mainly be between four and eight hours. In some instances though, depending on the circumstances, short-term measurements may be all that is required to make decisions on the risk of exposure and level of control. The number of people you decide to sample at each location will depend on the nature of exposure and size of the exposed workforce.


Fixed place monitoring is appropriate in those areas of the workplace where it is impractical to collect personal samples, eg outside a toll booth. Such fixed sampling is useful for determining the effectiveness of your control measures and for measuring background concentrations of DEEEs.


How Euro Environmental can help

If you don’t know where to start with your workplace risk assessment, we can help! Our specialist team can visit your workplace and carry out an appropriate exposure assessment.

Contact Us or call 01302 311131



If you need any further assistance or would like to know more please get in touch and we will get back to you as soon as we can.

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