Miguel Tato Diogo

Department of Mining Engineering,Faculty of Engineering,University of Porto,Porto 4200-465,Portugal

Keywords:Nitrogen monoxide Nitrogen dioxide Carbon monoxide IOELVs European Directive 2017/164 Underground mining Tunnelling

ABSTRACT Directive(EU)2017/164 establishes a fourth list of indicative occupational exposure limit values(IOELVs)to protect workers from risks of exposure to hazardous chemicals.It states that in underground mining and tunnelling,Member States may benefit from a transitional period regarding IOELVs for nitrogen monoxide,nitrogen dioxide,and carbon monoxide,during which the existing established IOELVs may be applied.The European Advisory Committee on Health and Safety at Work questions the technical feasibility of the proposed IOELVs in underground mining (CO,NO and NO2) and tunnelling (NO and NO2).Challenges arise concerning the availability of measurement methodologies for compliance with proposed IOELVs (NO2) in underground mining and tunnelling environments.

1.Introduction

In 1989,the Council of the European Communities adopted the Directive 89/391/EEC of 12 June,in the introduction of measures to encourage improvements in the safety and health of workers at work.It establishes general principles concerning the prevention of occupational risks,the protection of safety and health,the elimination of risk and accident factors,the informing,consultation,balanced participation and training of workers and their representatives.Regardless of previous Directives,Council Directive 89/391/EEC set a landmark on occupational health and safety of workers,often referred to as the ‘‘framework directive” and the‘‘basic law” on occupational safety and health in the European Union [1].

There are nineteen individual Directives within the scope of Article16 paragraph 1 of the Framework Directive that are currently in force,namely Directive 1998/24/EC of 7 April on the protection of the health and safety of workers from the risks related to chemical agents at work,which is the fourteenth individual Directive.This Directive aims to lay down minimum requirements for the protection of workers from risks to their safety and health arising,or likely to arise,from the effects of chemical agents that are present at the workplace or because of any work activity involving chemical agents.

Directive 1992/104/EEC of 3 December on minimum safety and health protection of workers in the surface and underground extractive industries:This Directive aims primarily to improve the safety and health protection of workers in the surface and underground extractive industries that are considered as a sector of elevated risk for the workers’ health (twelfth individual Directive).Risk management and decision-makers face demanding challenges when taking into consideration particular and endogenous needs,as within the mining industry [2].

Mining and the miners’ safety have always been a concern.International Labour Organization(ILO)Safety and Health in Mines Convention (C176)in 1995 concerning Safety and Health in Mines states ‘‘Considering that workers have a need for,and a right to,information,training and genuine consultation on and participation in the preparation and implementation of safety and health measures concerning the hazards and risks they face in the mining industry (...).” [3].

Regulatory approaches are an essential starting point regarding prevention.In 1997 the South African Department of Minerals and Energy (DME) introduced Directive B7,Health and Safety Conditions at Continuous Miners in Coal Faces and it ‘‘led to the significant positive changes to dust control systems employed in South African coal mines” [4].

Related to chemical agents and the protection of workers against risks to their health and safety,including the prevention of such risks,arising or likely to arise at work from exposure to chemical,physical and biological agents considered harmful,Council Directive 80/1107/EEC of 27 November 1980 was published(no longer in force) [5].In this context,‘‘agent” means any chemical,physical or biological agent present at work and likely to be harmful to health.

In 1998,regarding the protection of the health and safety of workers from the risks related to chemical agents at work,the Council of the European Union,adopted the Council Directive 98/24/EC.It lays down minimum requirements for the protection of workers from risks to their safety and health arising,or likely to arise,from the effects of chemical agents that are present at the workplace or as a result of any work activity involving chemical agents.

The Commission Directive of 29 May 1991 established indicative limit values (ILVs) by implementing Council Directive 80/1107/EEC on the protection of workers from the risks related to exposure to chemical,physical and biological agents at work(91/322/EEC) [6].

In 2000,a first list of indicative occupational exposure limit values (IOELVs) in implementation of Council Directive 98/24/EC on the protection of the health and safety of workers from the risks related to chemical agents at work was published through the Commission Directive 2000/39/EC of 8 June 2000 [7].

The Commission Directive 2006/15/EC of 7 February established a second list of indicative occupational exposure limit values in implementation of Council Directive 98/24/EC and amending Directives 91/322/EEC and 2000/39/EC [8].

A third list of IOELVs was established in 2009 by Commission Directive 2009/161/EU of 17 December,in implementation of Council Directive 98/24/EC and amending Commission Directive 2000/39/EC [9].

Currently,the Commission Directive (EU) 2017/164 of 31 January 2017 established a fourth list of indicative occupational exposure limit values set at Union level,to protect workers from risks arising from exposure to hazardous chemicals,pursuant to Council Directive 98/24/EC and amending Commission Directives 91/322/EEC,2000/39/EC,and 2009/161/EU.All the established Council Directives are shown in Fig.1.

2.Methods

The present work aims to present a brief review of the European legal framework(published Directives and related documents)concerning underground mining and tunnelling within the scope of the Commission Directive (EU) 2017/164 publishing a fourth list of IOELVs and the established transitional period,as stated in its Article 6 for underground mining and tunnelling environments.Member States can benefit from a transitional period ending at the latest on 21 August 2023,concerning the application of the limit values for nitrogen monoxide,nitrogen dioxide,and carbon monoxide.

3.Discussion

3.1.On occupational exposure limit values

Dust concentration in mining environments has been a demanding and unavoidable research topic.From the workers’health point of view,respirable dust inhale can have an adverse effect,and very simple yet effective measures such as water spray systems have been used for dust suppression [10].

First established definition through Council Directive 80/1107/EEC of 27 November 1980 on the protection of workers from the risks related to exposure to chemical,physical and biological agents at work as it states in its Article 2,‘‘limit value” means the exposure limit or biological indicator limit in the appropriate medium,depending on the agent.

In 1998,Council Directive 98/24/EC set definition for occupational exposure limit value(OELVs)‘‘means,unless otherwise specified,the limit of the time-weighted average of the concentration of a chemical agent in the air within the breathing zone of a worker in relation to a specified reference period.”What is also mentioned in Article 3 is that the Commission shall evaluate the relationship between the health effects of hazardous chemical agents and the level of occupational exposure through an independent scientific assessment of the latest available scientific data.These limit values shall be established or revised,taking into account the availability of measurement techniques.

There are two different types of OELs set at EU level:

Fig.1.European legal framework.

(1) Firstly,the Indicative Occupational Exposure Limit Values(IOELVs) are established in accordance with the Chemical Agents Directive.IOELVs are health-based occupational exposure limit values that are derived by SCOEL from the most recent scientific data available and adopted by the Commission,taking into account the availability of measurement techniques.They are threshold levels of exposure below which,in general,no detrimental effects are expected for any given chemical agent after short-term or daily exposure over a working lifetime.They constitute Union objectives and are designed to assist employers in determining and assessing risks and in implementing preventive and protective measures following Directive 98/24/EC.

(2) Secondly,Binding Occupational Exposure Limit Values(BOELVs) are established under the Chemical Agents Directive and the Carcinogens or Mutagens Directive.A BOELV for asbestos is set in the Exposure to Asbestos at Work Directive (2009/148/EC).BOELVs may be assessed at Community level and,in addition to the factors considered when establishing IOELVs,shall comprehend feasibility factors while maintaining the goal of health of workers at work.

3.2.Transitional period

The Commission Directive (EU) 2017/164 establishes a transitional period,as stated in Article 6 ‘‘In underground mining and tunnelling,Member States may benefit from a transitional period ending at the latest on 21 August 2023,as regards the limit values for nitrogen monoxide,nitrogen dioxide,and carbon monoxide”.Furthermore,during the regulatory transitional period,Member States may continue to apply the existing established IOELVs instead of applying the limit values established in the Annex of the above-mentioned Directive.Such prerogative comprehends two scenarios:(1) nitrogen monoxide(NO):the existing limit values established under the Annex to Directive 91/322/EEC; and (2)nitrogen dioxide (NO2) and carbon monoxide (CO):national limit values in force on 1 February 2017.

As an example of national limit values in force on 1 February 2017(in respect of nitrogen dioxide and carbon monoxide) the United Kingdom EH40,or EH40/2005 Workplace Exposure Limits,refers to the environmental hygiene guidance note issued by the United Kingdom’s Health and Safety Executive (HSE) [11].The guidance note contains a list of workplace exposure limits(WELs)(Table 1).It refers that during the transitional period,limits for the underground mining and tunnelling industries will be as follows:(1)for nitrogen monoxide a WEL of 30 mg/m3as an 8-hour TWA will be used;and(2)for carbon monoxide WELs of 35 mg/m3as an 8-hour TWA,and 232 mg/m3short term(15-minute TWA)are to be used.

These values will remain in place until the end of the 5-year extended transitional period (21 August 2023),when the lower value of 2.5 mg/m3for nitrogen monoxide,0.96 and 1.91 mg/m3for nitrogen dioxide and 23 and 117 mg/m3for carbon monoxide will be applied.

3.3.On the consulted parties

3.3.1.Advisory Committee on safety and health at work (ACSHW)

ACSHW,set up by Council Decision 2003/C 218/01 of 22 July 2003,has the task of assisting the Commission in the preparation,implementation,and evaluation of activities in the fields of safety and health at work.In its Proposal (Doc.819/15,adopted on 21/05/2015)on the preparation of a Directive establishing a 4th list of Indicative Occupational Exposure Limit Values(IOELVs),supplementing the one adopted by the (ACSH) on the 27/11/2014 (Doc.1893/14) [12].The Commission has been informed of challenges regarding measurement methodologies for NO2in mining and tunnelling environments and is checking the suitability of available approaches.

Within the ACSHW,the Employers Interest Group comments mentioned that in some countries the regulatory level of acceptability requires to be able to measure concentration below 1/10 of the OEL which is not compatible with the Limit of Detection(LoQ) of existing analytical methods.In this respect,the ACSHW acknowledges that there are issues related to the technical feasibility of the proposed IOELVs in underground mining and tunnelling–for nitrogen monoxide and nitrogen dioxide and underground mining–for carbon monoxide.

3.3.2.Scientific Committee on occupational exposure limit values(SCOEL)

The published Recommendation from the Scientific Committee on Occupational Exposure Limits for Nitrogen Monoxide -SCOEL/SUM/89 June 2014,presents the proposal for nitrogen monoxide(NO) [13]:(1) 8-hour TWA:2.5 mg/m3and (2) 15-minute STEL:not applicable.This Recommendation is based on compilations by WHO (1997) and the National Research Council of the National Academies (2012).Nitrogen monoxide has an Indicative Occupational Exposure Limit at EU level set in Directive 91/322/EEC (8-hour TWA:30 mg/m3).

SCOEL/SUM/89 states that‘‘(...)the major problem in deriving a recommended OEL for NO from occupational field studies is that NO reacts with air to form NO2,which is more toxic than NO due to local irritation of the pulmonary system.At occupational settings,both nitrogen oxides occur together,besides other components such as dust or Diesel particles.This complicates the interpretation of available occupational field studies,as it is difficult to determine the effects of a single exposure component separately.”

Recommendation from the Scientific Committee on Occupational Exposure Limits for Nitrogen Dioxide -SCOEL/SUM/53 June 2014 presents a proposal value for nitrogen dioxide (NO2) [14]:(1) 8-hour TWA:0.995 mg/m3and (2) 15-minute STEL:1.91 mg/m3.This Recommendation is based on compilations by WHO(1997),DECOS(2004),US EPA(2008),DFG(2005 and 2010),ACGIH(2012) and National Research Council of the National Academies(2012).

SCOEL/SUM/53 considers that ‘‘available human data on NO2obtained in working populations are reliable for recommending an 8-hour OEL,as these are seconded by both experimental human studies of shorter duration and experimental animal studies.”Further,it admits that‘‘in essence,with the presently available standard instrumentation the occupational exposure limit(OEL)of 0.995 mg/m3NO2,as recommended here,may not be adequately controlled in underground coal mines.”(SCOEL/SUM53,2013,pp.4).

Table 1 Comparative values for the new proposed limits and the existing ones.

The published EG/SUM/57 (October 1995) Recommendation from the Scientific Expert Group on Occupational Exposure Limits for Carbon Monoxide presents values for CO[15]:(1)8-hour TWA:23 mg/m3and (2) 15-minute STEL:117 mg/m3.

3.3.3.Standing working Party on the extractive industry (SWPEI)

To ensure continuity concerning questions previously dealt with by the Mines Safety and Health Commission,a Standing Working Party(SWP)on the Mining Industry has been established within the Committee(Article 5(4),of the Council Decision 2003/C 218/01).

According to Doc.754-EN/16 SWPEI -Meeting on 19th/20th April 2016,Luxembourg,Final Draft ‘‘NO2and NO values are dependent and depending on the mine,mining methods&machinery and on ventilation possibilities,optimisation can be achieved but a comprehensive solution is required.It was also stressed that we compete in a global commodities market and the state in of the various mines across the EU is very different.”

The SWPEI position for CO ‘‘Not to take CO on the fourth list of OELs or to include a footnote that the proposed value is not applicable to the extractive industry.Creation of a working group to compile the technical,economical and social effects of the SCOEL recommendation for NO,NO2,CO”.

3.3.4.Sectorial social dialogue Committee,extractive industries (SSDC EI)

At sectorial level,the social dialogue underwent an important development in 1998,when the Commission decided on the establishment of sectorial dialogue committees promoting the dialogue between the social partners in the sectors at European level(Commission decision of 20 May 1998–98/500/EC).

The Joint Opinion of the SSDC-EI on the Draft Recommendations of the SCOEL for occupational exposure limits on the workplace for NO2and NO,published in 2014,explains that‘‘There are currently no devices available for use in underground mines that could ensure a reliable,state-of-the-art mobile and permanent monitoring of occupational exposures at the level of the SCOEL recommendation for NO2.” [16].

As for CO,the SSDC-EI position is:‘‘Scientific evaluation is not conclusive; modification relates only to groups exposed to special risks; preferred value approach; technically and economically not feasible; consider the special conditions in mining with regard to the employees.”

4.Final remarks

Such an open and complex issue does not comprise simple final remarks,without further comprehensive research and analysis.The Opinion of the Sectorial Social Dialogue Committee for the Extractive Industry on the Draft Recommendations of the Scientific Committee on Occupational Exposure Limits (SCOEL) for occupational exposure limits on the workplace for NO2and NO,published a few recommendations that can be taken into account as final remarks for the present legal framework review.

Answering the question:‘‘Are there any important or critical publications that have not been taken into account?”,the document identifies available epidemiological studies,such as the two studies conducted in the German potash and coal mining industry respectively.Also the study carried out for the exposure situation of German hard coal miners for the components nitrogen monoxide and nitrogen dioxide by Dahmann et al.has been recognised as a leading study [17].

Further epidemiological studies(at date of publication)for concentrations on a higher level will be conducted in the near future.

To the question ‘‘Is there any other relevant information?” the joint opinion document sums that when SCOEL published its recommendations,the Commission and the tripartite advisory committee should specifically ‘‘consider the practical risk management alternatives which are feasible in different types of industry where nitrogen dioxide occurs.” Furthermore,according to(Directive 98/24 from 7 April 1998),limit values shall be established or revised,taking into account the availability of measurement techniques.

Preventive and protective measures such as ventilation in underground mining and tunnelling environments should be approached as effective.Alongside regulatory procedures,R&D findings can as well be preventive measures such as threedimensional computational fluid dynamic (CFD) models to assess methods for mitigating dust dispersion to ensure a safe working environment in the mine [18].Similar studies provide some new design concepts for a cost-efficient underground mine ventilation system to control oxygen supply and hazardous gas emission,due to diesel engines,as major sources of hazardous gases (CO,CO2,NOX,SO2)posing relevant danger to miners and mining operations [19].

In 2000,and with a scope of 15 years,a Dust Monitoring Program(DMP)started within member companies from the European Industrial Minerals Association (IMA-Europe).The resulting database,built on personal exposure measurements,can be a tool to protect workers from health risks resulting from exposure to respirable dust and quartz [20].

And Council Directive 98/24/EC states in Article 6-Specific protection and prevention measures,No.2,(b) ‘‘application of collective protection measures at the source of the risk,such as adequate ventilation and appropriate organizational measures”; Council Directive 92/104/EEC publishes in Article 7 -Ventilation,7.1.‘‘All underground workings to which access is permitted must be ventilated in an appropriate manner.”