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  • The Australian Institute of Occupational Hygienists (AIOH) have issued an updated guidance on diesel exhaust particulate and health risks. The document retains the original recommendation that levels of DPM should be controlled to; below 100µg/m³, as an 8 hour average value, measured as submicron elemental carbon (EC).
    In South Africa, the regulatory authority (Department of Minerals and Energy) for Mine Health and Safety would normally promulgate regulations controlling the exposure of the workforce to below a specified Occupational Exposure Limit (OEL), which has a similar definition to a TLV.  Under the Mine Health and Safety Act (Act 29 of 1996) a Guideline for a Mandatory Code of Practice on the use of diesel engines should also be considered from a health and explosion prevention perspective. The South African Bureau of Standards (SABS) also publishes engine performance standards that can be made legally binding to OEMs and industry when referred to in legislation.
    There are currently no personal occupational exposure limits or legally binding tailpipe emissions standards in South Africa for DPM.  Mining companies are however obliged to conduct risk assessments in terms of Section 11 of the Mine Health and Safety Act (Act 29 of 1996) on all factors that could adversely affect the health and safety of the workforce and institute appropriate mitigation measures, where no local regulations exist, international best practice should be utilised. OEMs are also required to provide a full disclosure, in terms of Section 21 of the Mine Health and Safety Act (Act 29 of 1996) of the health and safety impact of the equipment being sold to a mining company and advice on appropriate measures that can be taken to eliminate or reduce the risk.
    The Group Environmental Engineers “GEE” committee recognise that several International Agencies have imposed limits for DPM, but also that these limits have been developed in countries where:

  • Higher quality diesel fuel with low sulphur content is used;

  • Latest generation diesel engines are used;

  • Maintenance staff is adequately trained and available for employment to work on these units; and

  • Exhaust purification systems are used extensively.

To this extent, the GEE’s recommendation for action is to introduce an interim DPM exposure control value and gradually lower this exposure control value by means of a “phased-in” approach as follows:

  • A DPM exposure control value of 350µg/m3 (TC) up to 31 December 2013

  • A DPM exposure control value of 250µg/m3 (TC) for 01 January 2014 to 31 December 2014

  • A DPM exposure control value of 200µg/m3 (TC) for 01 January 2015

  • As from 01 January 2016 a DPM exposure control value of 160ug/m3 (TC) will be adopted.  This level is however subjected to review should new knowledge on the risks associated with excessive exposure to DPM become available.

  • Currently, exposure limits are legislated in Australia, Canada, United Kingdom and United States of America.  These limits are based on the measurement of particulate constituents as indicated in the table below:

  • Regulatory/Agency               Exposure Guidelines/Limits              Substance Measured
    Canada (Ontario province       400µg/m³                                             Total Carbon (TC)                                        
    US MSHA                               160µg/m³                                              Total Carbon (TC)
    Australia                                  160µg/m³                                              Total Carbon (TC)
                                                    120µg/m³                                              Elemental Carbon (EC)
     
    Internationally, DPM is regulated via two mechanisms i.e. Occupational Health and Safety Standards and Tailpipe Emission Standards. Where diesel engines are used in confined spaces, their operation is regulated by occupational health standards in addition to tailpipe emissions.