Diesel engine exhaust emissions (DEEEs) and non-road mobile machinery (NRMM) – the risk to construction (and other) workers

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Recent headline news has made us all too aware of the effects of air pollution on the climate and our health, and this is contributed to significantly by emissions from combustion engines installed in non-road mobile machinery (NRMM) – used extensively in the construction industry. The Mayor of London has responded by targeting the sector with the world’s first “ultra-low emissions zone” for NRMM and – nationwide – under the Clean Air Strategy, the government will be exploring the use of environmental permitting to address the problem.

Whilst “cleaner” engines have started to become available, those powered by diesel are still the most widely used on construction sites, and inhalation of diesel engine exhaust emissions (DEEEs) can cause a number of ill health effects – both short term and long term, including – evidence suggests – an increased risk of lung cancer. According to HSE statistics, each year, around 3,000 workers in construction suffer with breathing and lung problems they believe were caused or made worse by their work. That is 0.14% of workers in the sector, compared with 0.09% of workers across all industries.

So, what should be done to prevent this risk?

The below HSE guidance “Control of diesel engine exhaust emissions in the workplace” includes control measures which can be implemented quickly and easily on a construction site and in other workplaces, e.g. switching off engines when not required, and adopting a programme of regular engine maintenance.

But a reduction in pollution can also be achieved through the use of cleaner fuels. Alternatives include low sulphur diesel (LSD), ultra low sulphur diesel (ULSD), biodiesel, blends of biodiesel with petroleum diesel and emulsified diesel. Low sulphur diesel has sulphur content of 300 – 500ppm and reduces particulate matter (PM) by 10 – 20% compared to non-road diesel fuel (which has a sulphur content or 3000 – 5000ppm).

And pollution control equipment such as diesel oxidation catalysts or diesel particulate filters can be retrofitted directly onto an engines exhaust system.

Under CDM 2015, design decisions made during the pre-construction phase of projects should also be considered, as these too have a significant influence on the health and safety of everyone affected by the work. For example, lighter buildings, often delivered by low carbon building methods (with no increase in cost), can reduce on-site excavation and heavy machinery due to the requirement for smaller foundations. An example of this is the timber structure of Dalston Works in London which weighs a fifth of its concrete equivalent. And as most the construction was off-site, there were 80% fewer site deliveries than usual.

The below guidance can be downloaded by clicking the link: http://www.hse.gov.uk/pubns/priced/hsg187.pdf and more information is available on the HSE web page: http://www.hse.gov.uk/construction/healthrisks/cancer-and-construction/diesel-engine-exhaust.htm. Alternatively, please contact us on 07896 016380 or at fiona@eljay.co.uk, and we’ll be happy to help.

Control of diesel engine exhaust emissions in the workplace

Legislation

The law requires that a suitable and sufficient assessment of the risks to health which arise from exposure to hazardous substances is made, eg DEEEs. This is covered by the Health and Safety at Work etc Act 1974 and several other regulations, in particular the Control of Substances Hazardous to Health Regulations 2002 (as amended) (COSHH) and the Management of Health and Safety at Work Regulations 1999. Having completed the assessment, there is a further duty to take the necessary steps to prevent or adequately control exposure to the hazard, and to use and maintain the relevant controls.

Risk assessment (COSHH regulation 6)

The health risk assessment will help you to assess the risks to health from exposure to hazardous substances and identify the necessary steps needed for controlling these risks. As workload, frequency of work, and work practices may change over a period, it is necessary to regularly review the assessment. In all but the simplest cases, you should record the assessment.

For DEEEs, the aim of the health risk assessment is to decide on the level of potential exposure, and then on the preventive measures or the level of control which you will need to apply. For example, if there is obvious blue or black smoke in the workplace, the controls need to be more stringent. In some circumstances, such as if there are visible exhaust emissions or complaints of irritancy, the assessment may necessitate carrying out monitoring to assess the effectiveness of the controls.

In order to carry out a suitable and sufficient risk assessment you need to ask a series of questions, find answers and then come to a conclusion. These questions include:

  • How likely is it that exposure to DEEEs will happen?
  • Who could be affected, to what extent and for how long? How many people are potentially exposed to the DEEEs? Can the exposures be avoided?
  • Have there been any ill-health complaints from potentially exposed groups? If yes, what has been done about it?
  • Is the engine being operated at full speed or left idling? What is the purpose of running at idling speed or full speed. Can it be avoided?
  • What is the state of the engine, and how many miles or hours have been completed? Can the engine efficiency be improved, and can operating times and distances be reduced? Improving the efficiency of the engine will also bring financial benefits.
  • What happens to the exhaust emissions: do they enter directly into the workplace, or are they piped away or processed through a treatment system? Could they trigger your fire detection system?
  • Is there visible smoke near the exhaust point? What is the type of smoke, ie white, black or blue? How could it be avoided? Is there a visible haze in the workplace? Can it be avoided and how?
  • What controls are in place to comply with COSHH? Are they satisfactory?
  • Are there soot deposits in the workplace; how significant are they? What can be done to avoid them? What methods are in place for regularly cleaning the workplace?
  • How many engines are running at any one time? Are they all necessary?
  • Is it necessary to use diesel engines, or can alternative power sources be used?

Prevention and control of exposure (COSHH regulation 7)

The answers to the questions in paragraph 17 will guide you in deciding on the actions necessary to prevent or control exposure to DEEEs in the workplace. The control measures you choose need to be based on: the levels of risk and exposure; the type of workplace; present work practices; cost and benefit factors. Because of the variety of workplaces where exposure may occur, the potential exposure and the level of risk will be different. For example, there may be increased exposure where fork-lift trucks are being used in a warehouse all day for moving goods, whereas in a maintenance depot the exposure may be intermittent as the vehicles enter, stay there for maintenance, and then leave.

Prevention

Health and safety legislation requires you to prevent the exposure of employees and others to substances hazardous to health. You should be able to prevent exposure to DEEEs by adopting one or a combination of options, for example:

  • changing the method of work;
  • modifying the layout of the workplace;
  • modifying the operations to eliminate exhaust emissions inside the workplace; or
  • substituting diesel fuel with a safer fuel or alternative technology where practicable, eg compressed natural gas, battery powered vehicles.

Your risk assessment should take account of any other risks posed by these alternative fuels and technologies, for example the use of alcohols may generate greater quantities of aldehydes with possible accompanying irritancy.

Control

There will be situations where it may not be reasonably practicable for you to prevent exposure to DEEEs. In these situations, you should consider the circumstances individually and take the necessary control measures to reduce exposure. These may include:

Engineering controls

  • the use of lower emission or more fuel-efficient engines where possible, eg higher engine injection pressures to reduce particulates, fitting exhaust gas recirculation systems to reduce gaseous oxide emissions;
  • the use of cleaner fuels such as low sulphur diesel fuels;
  • enclosing the exhaust tailpipe from which DEEEs are emitted, for example by using a fixed flexible hose with a tailpipe exhaust extraction system (see Figures 2 and 3);
  • using partial enclosure with local extraction ventilation (LEV) as shown in Figure 4;
  • the use of diesel exhaust gas ‘after-treatment’ systems such as catalytic converters to oxidise organic substances and gases, and catalysed and non-catalysed particulate traps to remove particulate matter;
  • using a combination of LEV and sufficient general ventilation, eg tailpipe exhausts with open doors or roof extraction;
  • using sufficient general ventilation, eg manual or mechanical roof extraction;

Practice and administrative controls

  • using processes or systems of work which will help you to reduce the generation of DEEEs, for example switching off engines when not required for a substantial period of time and adopting a programme of regular engine maintenance;
  • where practicable, reducing the number of employees directly exposed and their period of exposure, eg ensuring that office staff working adjacent to DEEE areas are not exposed, job rotation; and

Respiratory protective equipment (RPE)

  • as exposure to DEEEs is best controlled at source or by other means as described previously, RPE should only be used as a last resort. The RPE chosen should be suitable for protecting against the gaseous and particulate components. The use of nuisance dust masks as worn by cyclists are ineffective against DEEEs and, therefore, should not be used as a means of control in the workplace. Detailed information on RPE for use in the workplace can be found in the HSE guidance book HSG53 Respiratory protective equipment at work: A practical guide.

Use of control measures (COSHH regulation 8)

You should ensure that any control measures are properly used or applied. Employees should make full and proper use of any control measure or personal protective equipment provided by the employer, and report any defects to management for immediate attention.

Maintenance, examination and the testing of control measures (COSHH regulation 9)

You should ensure that all the measures provided to control exposure to DEEEs in the workplace are maintained in an effective state, and kept in efficient working order and in good repair. Where engineering controls are used, they should be thoroughly examined and tested at suitable intervals. LEV, for example, should be thoroughly examined and tested at least once every 14 months.

With the exception of disposable filtering facepiece respirators intended for single shift use, RPE should not be used unless it has had a recent thorough examination and maintenance. The interval between thorough examination and maintenance should not be more than one month.

You should keep a record of such examinations and tests of LEV and RPE for at least five years from the date on which they were made. The record should be readily available for inspection by employees or their representatives, or by enforcement authorities.

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:

  • to determine if there is a failure or deterioration of the control measures which could result in an obvious health effect, eg irritancy from exposure to DEEEs;
  • to determine whether any workplace exposure limit (WEL) or any in-house working standard has been exceeded; and
  • 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.

Personal monitoring for exposure to DEEEs

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 six 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, for example:

  • processes or operations where exposures are likely to occur;
  • the number, type and position of sources from which the DEEEs are released; and
  • which groups of employees are most likely to be exposed.

Fixed place monitoring

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.

What substances to monitor

Levels of carbon dioxide (CO2 ) above 1000 ppm 8-hour TWA in the workplace, may indicate faulty, poorly maintained or inadequately designed control systems in particular LEV or roof extraction systems. As measurement of the CO2 level is easily carried out and because it is a useful indicator of the overall adequacy of control measures, it may be used as one of the steps in any assessment of the level of exposure to DEEEs.

Respirable dust levels may be measured to help you assess the particulate exposure if, for example, the workload is particularly heavy. However, the levels measured will include particulates from all sources and not just the DEEEs.

In situations where personal exposure to carbon monoxide (CO) may be high (such as at toll booths and in car parks where the majority of vehicles are petrol driven) measurement of CO will provide an indication about the adequacy of controls.

Irritancy

As the definite causes of irritancy are unknown, if any of your workforce complain of this health effect, it is important to look for better means of control rather than to monitor for other gaseous constituents of DEEEs.

Health surveillance (COSHH regulation 11)

Under COSHH, no formal health surveillance is required by employers of those exposed to DEEEs or related emissions. However, if employees are concerned about the short or long-term health effects of exposure to DEEEs, they should discuss the problem with management. If still not satisfied with the outcome, they should voice their concerns with their union representative if available or the works safety representative. Furthermore, if management notices that employees are suffering irritancy effects following exposure to DEEEs, it may indicate that the controls have failed and prompt action is required.

Employers must provide information on health and related matters to employees or their representatives in accordance with the Safety Representatives and Safety Committees Regulations 1977 and the Health and Safety (Consultation with Employees) Regulations 1996. Such information allows employees or their representatives to help employers develop control measures.

Information, instruction and training (COSHH regulation 12)

Adequate information, instruction and training should be given to employees on the health hazards associated with occupational exposure to DEEEs and on the proper use of control measures. This information should also be made available to employee safety representatives or other appropriate people.

The information, training and instruction should enable employees to recognise obvious deterioration in the controls used (such as poor maintenance of engines, damage to extraction equipment or ineffective general ventilation), so they can report to employers who would then take the necessary action to rectify the situation.

 

Contains public sector information licensed under the Open Government Licence v3.0.