S Chelhaoui
email: samira.chelhaoui@ineris.fr

P Serre Combe
email: pierre.serre-combe@cea.fr

Overview of European and international regulation and standardisation activities

Keywords: hydrogen, fuel cells, regulation, standards, safety

International technical committees have been created insi de the ISO and IEC organisations so as to facilitate the world-wide industrialisation and commercialisation of hydrogen systems and fuel cells. The working group ISO TC 197 entitled Hydrogen Technologies has already published international standards and is very active in the edition of standards for all the hydrogen chain from production to end use. The working group IEC TC 105 focuses on fuel cell technologies. It is also currently drafting many standards for fuel cell applications (mobile, stationary, portable and micro fuel cells). At an international level, the UNECE is actively working for the publication of two Global Technical Regulations for vehicles fuelled with gaseous or liquid hydrogen. And, finally, many European projects intend to facilitate the implementation of a harmonised and well-adapted regulation and standardisation framework.

Introduction and definitions

Hydrogen based economy and associated energy converters fuel cell systems are meant to be part of the response to increasingly worrying ecological and economical issues embodied by either global warming or the depletion of fossil energy sources. Indeed, hydrogen shows many benefits in the field of air pollutant as its combustion reduces pollutant and greenhouse gas emissions (carbon dioxide…). Besides, energy conversion yields seem to be better and finally it allows fossil fuels dependant economy to rely on other energy loops. Hydrogen can virtually be produced from a wide variety of domestic sources. It can also provide a storage medium for intermittent and seasonal peak energy needs.

Hydrogen can be used as an energy carrier for many traditional technologies such as cars (direct combustion engines using hydrogen or hydrogen based mixtures, fuel cell systems), electrical plants, systems that provide heat and electricity for buildings, remote power unit systems, backup systems… .

Hydrogen technologies are under test across Europe (stationary power units, boats, city buses, cars…). Different challenges are being faced: technological, hydrogen production, hydrogen storage,… . Along with public acceptance, authorities legal approval for demonstration projects need to be gained.

In this context, regulation and standardisation will have to make their way to ease hydrogen technologies implementation.

A regulation could be a national or European statutory text that set compulsory expectations. It provides rules that are adopted by governmental bodies so as to regulate a particular kind of activity. Whereas standards do not have any legally compelling power, unless a regulation refers to this standard (harmonised standards).

Regulations are a mean to preserve public interests (health & safety or environmental issues for instance). Standards could suggest technical mean to fulfil legal expectation that serves public interests or could be for instance a way to standardised products and interface in order to ensure their world-wide technical compatibility.

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Standardisation related to hydrogen and fuel cells

General overview

Standardisation related to Hydrogen systems is in the hands of t he International Standardisation Organisation, which initiated in 1990 the ISO TC 197 dedicated to fuel cells. The scope of ISO TC 197 working group in order to develop and edit standards in the field of systems and devices for the production, storage, transport, measurement and use of hydrogen. As for fuel cell systems, they are considered as an electric device and therefore fall within the scope of the International Electrotechnical Committee. This Committee created in 1996 the IEC TC 105 dedicated to fuel cell systems with the purpose of preparing international standards regarding fuel cell (FC) technologies for all FC applications such as stationary FC power plants, FC for transportation, FC propulsion systems, auxiliary power units or portable FC power generation systems.

International standards, which are published by IEC and ISO should be transposed by CENELEC 1 and CEN 2 respectively and then would be applied at a national level. The illustration below shows the interfaces between International, European and national standardisation levels.

Illustration 1: liaisons between international, European and national standardisation

Each country can participate to the ISO and IEC standardisation activities:

Whether as a P-member, in this case it can vote drafts which circulate for vote, Or as an O-member, in this case it can only participate to meetings without voting.

ISO TC 197 P-members include Belgium (IBN), Denmark (DS), France (AFNOR), Germany (DIN), Italy (UNI), Netherlands (NEN), Spain (AENOR), Sweden (SIS), USA (ANSI), United Kingdom (BSI), Norway (SN), etc.

Among IEC TC 105 P-members, we can find Canada, Germany, China, France, Denmark, Italy, United Kingdoms, United States, Japan, Netherlands, Spain, etc.

European standardisation activities

European Hydrogen and Fuel Cell Technology Platform (EHP)

The main goal of the European Hydrogen and Fuel Cell Technology Platform (EHP) is to facilitate and accelerate the development and deployment of cost-competitive, world class European hydrogen and fuel cell based energy systems and component technologies for applications in transport, stationary and portable power. The platform is steered by a high level Advisory Council. The establishment of the HFP has been facilitated by the European Commission The structure of the EHP is illustrated below. 9/11

Regulation related to hydrogen and fuel cells

General overview

Up to now, in Europe, there is no specific regulation (Directive or International rule) dedicated to hydrogen and/or fuel cell systems.

Stationary applications

Regarding stationary applications, systems should comply with relevant European Directives Among these Directives, we can list:

Directive Reference

Low In France, there are many regulatory texts related to systems, using hydrogen as a chemical product depending on the context of use. Indeed, hydrogen systems safety requirements concern various regulation areas: health & safety at work, pressure vessels, electrical devices, transportation, industrial hazards etc. Most of these regulations evolve from European directives.

As far as stationary applications are concerned such as Hydrogen refuelling stations, fuel cell cogeneration unit, etc they should (among others) comply with industrial hazard related regulations. The Directive 96/61/CE related to major accidents (or its equivalent at national level) is therefore applicable. This Directive dedicated to industrial risk reduction, also known as he SEVESO Directive, concerns hazardous industrial plants. Hazardous plants are ranked in accordance with a formal list of activities and products and related thresholds. Hydrogen production falls within this list (Annex I -activity n°4.2).

It is interesting to point out that this Directive mentions that research / demonstration activities do not fall within the scope and constraints of its scope. This could concern for instance hydrogen refuelling stations built in the framework of a demonstration project.

Mobile applications

Today, there is no legislation, specifically dedicated to fuel cell and hydrogen vehicles. Nevertheless, hydrogen vehicles must be at some point approved so as to run on public roads with passengers onboard.

In this context, the UNECE (United Nations Economic Commission for Europe) aims at providing a regulation for hydrogen vehicles. The GRPE7 of the WP298 in Geneva works on it. The GRPE created an ad-hoc working group to publish regulations dedicated to hydrogen vehicles. These regulations are based on consensus between countries' members. Besides, there should not be contradictions with standards under development. Draft regulatory texts come from the EIHP project.

This ad-hoc group will propose two regulations dedicated to hydrogen vehicles and their components (liquid and gaseous) in the framework of the 1998 Agreement, which includes almost all countries (Europe, Japan, United States, China, Canada).

GTRs9 should concern vehicles equipped with: a fuel cell fuelled by hydrogen, or a hydrogen internal combustion engine, and/or auxiliary power units running on hydrogen, and/or hydrogen storage equipment (gaseous, liquid, solid). These GTRs will be made available in the next decade. There will not be any intermediate step with the introduction of an ECE regulation. In this perspective, the European Commission plans to publish a European Regulation on Hydrogen vehicles that compiles the two ECE draft Regulations. There will be two: documents: a political one for discussion and adoption in the European Parliament and in the Council and a technical one discussed and adopted at Commission level .

European projects dealing with RCS activities

In Europe, there are projects that deal specifically with regulation, codes and standards related to hydrogen and fuel cell systems. These projects aim at undertaking prenormative research towards harmonised regulations and standards. Projects' examples are given below.

HySociety project

HySociety is an European FP610 project aims to support the introduction of a safe and dependable hydrogen-based society in Europe. by. It addresses not only non-technical barriers such as codes and standards for infrastructure implementation, public safety concerns, social and economic impacts, but also the changing trends in industrial structures and in the European economy. It aims at analysing gaps and needs in the field of regulation, codes and standards for hydrogen systems and promotes international cooperation and dissemination for hydrogen regulation, codes and standards.

HarmonHy project

HarmonHy project is an European FP6 project which intends to make an assessment of activities on hydrogen and fuel cell regulations, codes and standards on a world-wide level. On this basis gaps will be identified and propositions to solve fragmentation will be made. It intends to realise the state of the art of current RCS activities related to hydrogen, as an energy carrier and of prenormative research (on the basis of current demonstration projects for hydrogen and fuel cell systems). Finally, HarmonHy intends to elaborate a proposal for action plan and roadmap for further work towards regulations, codes and standards harmonisation on an international level.

4

  The glossary will be available as Edition 2 of IEC/TS 62282-1 IEC 62282-2 (2004-07) English and French Fuel cell technologies -Part 2: Fuel cell modules IEC 62282-3-2 (2006-03) English and French Fuel cell technologies -Part 3-2: Stationary fuel cell power systems -Performance test methods IEC/PAS 62282-6-1 (2006-02) English Fuel cell technologies -Part 6-1: Micro fuel cell power systems -Safety

IEC standards European standards (EN) ISO IEC CEN CENELEC

  During the standardisation process, several steps have to be made before the publication of a new standard as an International Standard. These steps are listed in the table below.

	Stage		Contents	Voting period
	Proposal	A new work item proposal (NP) is submitted for vote by the members of the relevant TC/SC 3 to determine the inclusion of the work item in the	3 months
		programme of work
		A working group is set up Successive working drafts (WD) may be
	Preparatory	considered until the working group is satisfied that it has developed the
		best technical solution to the problem being addressed.
		First committee draft (CD) is available, it is registered by the ISO
	Committee	Central Secretariat. It is distributed for comments and, if required, voting, by the P-members of the TC/SC. Several CD may be required	3 to 6 months
		until consensus is reached.
	Enquiry	A Draft International Standard is proposed and voted. If DIS is disapproved, a new one circulates for vote	5 months
	Europe F. International Approval	UTE ISO & AFNOR Final DIS circulates for final vote. If FDIS is disapproved, a new one circulates for vote	compulsory voluntary 2 months
	G.B.	BSI	BEC	National standards -Examples :
	All.	DIN	VDE	Standards NF -BS -DIN, Standards NF-EN, BS-EN, DIN-EN,
	E.U.	ANSI	ANSI	Standards NF-ISO, BS-ISO, DIN-ISO,
	CA.	SCC	SCC	Standards DIN/DKE-CEI, BS-CEI,
	Deliverable	Type	Contents
			Normative
	Standards (IS)	Consensus at	Standardisation in a specified technological field
			international level
			Normative
	Technical Specification	Consensus within the	Similar to the standard but international consensus is not
	(TS)		technical committee	reached or standardisation is not possible yet
			or subcommittee
			Informative	An informative document containing information of a
	Technical Report (TR)	Consensus within the	different kind from that normally published in a normative
			TC or SC	document.
	Publicly Available Specification (PAS)	Normative Consensus within the working group	It is published to facilitate the development of a technology, before IS is published.
	1 European Committee for Electrotechnical Standardization
	2 European Committee for Standardisation

Publication

The final text (with minor editorial changes, if necessary) is sent to the ISO Central Secretariat which publishes the International Standard. 2 months Review All International Standards are reviewed at least once every five years by the responsible TCs/SCs. P-members vote if the IS should be confirmed, revised or withdrawn Table 1: Main stages of standardisation process

As the duration to obtain international standards for Hydrogen and Fuel Cell systems may be quite long whereas sometimes standardisation can be an urgent need for new systems, intermediate documents can be produced by the standardisation technical committee (ISO or IEC) before international standards are made available. All, these documents facilitate deployment of new Hydrogen or FC systems. The table below lists these standardisation committees output documents.

Table 2 :

 2 Main deliverables of ISO and IECThe following table proposes an update of ISO TC 197 working groups, activities and progress.

	Reference

3 Technical Committee and Sub-Committee

4/11

The illustration below illustrates the standards development processes and associated deliverables.

Illustration 2

2.2. ISO TC 197 activities

2.2.1. Published standards

Table 5 :

 5 Documents published by IEC TC 105The following table makes an update of activities of each WG of IEC TC 105.

	stacks and systems

4

FCTESTNET is a European Project (achieved in 006) which aimed at compiling and harmonising testing procedures for fuel cells,

Table 7 :

 7 Directives that can be applied for H 2 and FC systemsThese Directives are «New Approach»Directives. They set safety objectives. Means to reach these requirements are detailed in « harmonised standards ». Up to now, there is no «harmonised standard» for hydrogen and fuel cell systems.

	voltage73/23/EEC
	Simple pressure vessels	87/404/EEC 90/448/EEC
		89/336/EEC
	Electromagnetic compatibility	92/31/EC
		98/13/EC
	Machine98/37/EC
	Equipment intended for use in potentially Explosive Atmospheres (ATEX)	94/9/EC
	Pressure equipment97/23/EC
	Gas appliances90/396/CE

International Council Code (Etats-Unis)

National Fire Protection Association (Etats-Unis)

Working Party on Pollution and Energy (GRPE)

World Forum for Harmonisation of Vehicles Regulations (WP29)

Global Technical Regulations

Framework Programme (EU)

Illustration 3: EHP structure

The main objective of the Initiative Group on Regulation Codes and Standards is to accelerate the implementation of harmonised regulations and standards for hydrogen and fuel cell systems, commensurate with requirements for public safety and use for hydrogen and fuel cell technologies in the European Union. The IG RCS aims also at providing guidance and recommendations to the Advisory Council (AC) and competent bodies at EU level and providing inputs to the Steering Panels of the Strategic Research Agenda (SRA) and Deployment Strategy (DS).

The long-term objective is to develop and adopt a European regulation well adapted for hydrogen and fuel cell technologies. IG RCS works in close collaboration with:

European projects dealing with regulation, codes and standards (HYSAFE, HarmonHy, HySociety, etc.), International, European and national standardisation committees (ISO, IEC, CEN, CENELEC, ICC 5 , NFPA 6 , etc.), The other Initiative Groups of the Platform.

2.5. Joint Working Group CEN/CENELEC: Gas appliances -Fuel cell gas heating appliance -Fuel cell gas heating appliance of nominal heat input inferior or equal to 70 kW (prEN 50465)

This working group was initiated by Germany in order to accelerate the edition of a European standard on fuel cell systems. This under progress standard will be published as a European one and will then be proposed at international level.

HYSAFE Network of Excellence

The European Network of Excellence HYSAFE -Safety of Hydrogen as an Energy Carrier -is a FP6 programme which started in 2004 for a 5 years duration. The HySafe network focuses on safety issues relevant to improve and co-ordinate the knowledge and understanding of hydrogen safety and support the safe and efficient introduction and commercialisation of hydrogen as an energy carrier of the future, including the related hydrogen applications. The overall goal of HySafe is to contribute to the safe transition to a more sustainable development in Europe by facilitating the safe introduction of hydrogen technologies and applications. Among its main objectives, HySafe shall provide contributions to EU safety requirements, standards and codes of practice. A work package co-ordinated by INERIS is specifically dedicated to this activity.

Main missions of this WP consist in:

Ensuring by active participation to targeted standardisation (ISO, IEC) / UN ECE groups that consensual knowledge on hydrogen safety is adequately taken into account in the process of building new standards and regulatory requirements, Promoting consensus within EC countries on safety related standardisation / regulatory aspects, Following progress of appropriate RC&S related to hydrogen technologies, Following and report on the progress made by the European Hydrogen and Fuel Cell Technology Platform (EHP) and the HarmonHy project, Providing up to date information to HySafe partners on the status of standardisation and UN ECE regulatory development through our webpage, Reporting on standardisation and regulatory development and related WP16 contribution to the HySafe partners. HYSAFE WP16 intends also to work in close co-operation with other EU and international projects in the field of prenormative research.


D Carson

S Chelhaoui
email: samira.chelhaoui@ineris.fr

S Chaudourne

M Guerraz

M Latroche

A Percheron Gueguan

French Project PLUSPAC: Development of a hydrogen storage unit for an optimisation of stationary FC systems SAFETY OF METAL HYDRIDES

Keywords: Metal hydrides, safety, reactivity 1 The French PLUSPAC Project

One of the objectives of the French project PLUSPAC (Local Production and hydrogen Storage Unit for an optimisation of Fuel Cell stationary systems), coordinated by the Energy Research Centre of Veolia Environment is to evaluate the performances of hydrogen storage in metal hydrides for the energetic optimisation of a stationary fuel cell system. INERIS was in charge to assess the safety of metal hydrides as a storage mean. As very few information is available regarding the safety of intermetallic compounds developed within PLUSPAC project, experimental tests have been performed so as to get information about the reactivity of the powder (reaction with air, with water, thermal decomposition). Tests have been performed on activated (15 and 30 cycles) and no activated powders, and also on an other intermetallic compound, which is supposed to be reactive. Nevertheless, none of the tests have shown any adverse reaction, neither with air, nor with water, nor when exposed to high temperatures. Today, it appears that metal hydrides tested have a safe behaviour when exposed to air, water and high temperatures. Further tests would be necessary to investigate other materials.

2/11 associated with a fuel cell, would meet both the power and thermal energy variable requirements of a stationary site.

One of the project objectives was to show the feasibility of a hydrogen buffer tank within this kind of CHP unit, and then to develop and test this storage under laboratory conditions. A constant hydrogen production would allow the reformer to run in an optimal way. However, the hydrogen consumption of the fuel cell is variable according to the energy demands of the user. A buffer tank flattens out the energy loads, thus improving the performances of the system.

Metal hydrides have been selected as hydrogen storage materials for the buffer tank for several reasons. First, they allow to store hydrogen safely (due to low equilibrium pressures at room temperature), with reliability and energy profitability (with no compression and a temperature close to the ambient one). On the other hand, these metal hydrides can also absorb most of the hydrogen at constant pressure, which enables the storage of a significant amount of hydrogen for a given lowpressure range. Furthermore, due to their volume capacities, metal hydrides have a very good compactness in comparison with other storage technologies ( liquid hydrogen, gaseous hydrogen under very high pressure).

As a first step of the project, specifications were determined by Schneider Electric and the Energy Research Centre of Veolia Environment on the basis of an analysis of the thermal and power needs of a representative site. On this basis, CEA has worked on a model of the thermal and mechanical behaviour of the hydrogen solid storage. Simultaneously, CNRS developed a metallic powder, which matches up to the defined specifications. The powder was tested by INERIS under various conditions (reaction to air, water, and coolant on a wide temperature range), with the final objective of filling in a tank developed by CEA with this powder. Then, the fitted tank has been tested on a load under laboratory conditions. This energy storage would eventually be used for other applications. Currently, the development of a secured and environmentally friendly tank is one of the keys of hydrogen economy breakthrough. Energy storage turns out to be essential for any decentralised hydrogen production system: using intermittent renewable energy sources or fuel cell based emergency power source.

The hydride

For this study, LaNi5 substituted derivatives (AB5-type compounds) have been chosen as hydrogen storage materials to fulfil the criteria related to the specific application. In order to adapt the thermodynamic properties of LaNi 5 compound, the substitutions of tin for nickel or of mischmetal for lanthanum (Mm stands for mischmetal, a mixture of lanthanum, cerium, neodymium and praseodymium) have been investigated. Several studies report that the substitution of a small amount of tin for nickel in LaNi 5 -type intermetallic compounds modifies the thermodynamic properties of the resulting hydride phase (decrease of the plateau pressure, hydrogen storage capacity and hysteresis ratio) [START_REF] Luo | Thermodynamic and degradation studies of LaNi 4.8 Sn 0.2 -H using isotherms and calorimetry[END_REF][START_REF] Luo | Thermodynamic studies of the LaNi 5-x Sn x -H system from x = 0 to 0.5[END_REF]. In addition, tin significantly improves the cycle life under hydrogen gas cycling [START_REF] Lambert | Investigation of hydriding properties of LaNi 4.8 Sn 0.2 , LaNi 4.27 Sn 0.24 and La 0.9 Gd 0.1 Ni 5 after thermal cycling and aging[END_REF][START_REF] Bowman | The effect of tin on the degradation of LaNi 5-y Sn y metal hydride during thermal cycling[END_REF]. Chemical replacement of the La by Mm in order to achieve cost reduction is of interest for a commercial application. For comparison, a Mn substituted compound was also investigated in the present work as Mn substituted sample is expected to be highly reactive.

Two intermetallic compounds (La 0.9 Ce 0.05 Nd 0.04 Pr 0.01 Ni 4.63 Sn 0.32 and LaNi 4 Mn) have been synthesised by induction melting of the pure elements under vacuum or argon atmosphere followed by annealing at 1123 K for 7 days. The composition and homogeneity were checked by X-ray diffraction (XRD) with Cu K radiation, optical metallography and electron probe micro-analysis (EPMA). All samples were found to be single phase with composition very close to the nominal ones. About 4 to 10 g of sample were ground mechanically under argon and activated by fifteen or thirty solid-gas cycles with a conventional Sievert's type apparatus (volumetric method). Each cycle consists in an absorption under 3.5 MPa of hydrogen gas at 75°C followed by a desorption under primary vacuum. After cycling, all samples were kept under inert atmosphere (Ar or vacuum). The different sample preparations are summarised in Table 1.

CompositionNumber of cycles (N)Weight (g)

La 0.9 Ce 0.05 Nd 0.04 Pr 0.01 Ni

3

The safety tests

Objectives of the tests

Metal hydrides were considered safer, compared with compressed or liquefied hydrogen storage for the reason that this storage technology did not rely on high pressure or could not be associated with a rapid hydrogen discharge in case of breach for example.

However, there is very few data (poor literature) on metal hydrides (intermetallic powders) behaviour when exposed to air, water, coolant and either thermal stability, though some activated hydrides are known to be pyrophoric. It is today necessary to get good data on metal hydrides behaviour, otherwise safety analysis of a hydrogen system would be very limited and a public use of these systems could be delayed [5]. Thus, INERIS decided to undertake an experimental program to get a better insight into intermetallic powders safety characteristics.

In this context, in the course of the French project entitled PLUSPAC, which aims at developing and evaluating a metal hydride tank for hydrogen storage, INERIS has performed the following tests: intermetallic compound 2 behaviour when exposed to air, intermetallic compound behaviour when exposed to water, intermetallic compound behaviour when exposed to coolant, and finally, intermetallic compound thermal stability.

Experimental means

Experiments have been carried out in our Chemical Reaction Safety Lab. This lab is in charge of assessing thermal stability of chemical products and to characterise chemical reactions. It is equipped with various equipment.

The following lab equipment has been used to assess Metal hydrides safety characteristics:

The DSC (Differential Scanning Calorimeter): it measures the difference of thermal flow between a test sample and a reference sample, when submitted to a thermal cycle (steady temperature increase). The DSC scans exothermic or endothermic reactions and allows to determine the temperature at which the sample becomes unstable as well as the associated enthalpy.

Samples

The samples in the form of a fine powder were provided by the Laboratoire de Chimie Métallurgique des Terres Rares (CNRS) Thiais France in sealed vials under vacuum (see illustration 2). Once opened in a glove box, the remaining sample was placed in a small closed bottle and stored at ambient temperature.

Samples were of both non-activated and activated types (15 or 30 cycles of charge and discharge). We therefore had to develop new laboratory practices in order not to contaminate samples with air.

Sample code

Sample reference number

Composition

Activation with hydrogen

2R

Main tests results

Preliminary tests

A few milligrams of the metal alloys were exposed to air in the form of a small pile on top of a thermocouple at ambient temperature to see whether the powder would spontaneously ignite. No ignition, incandescence, temperature rise, or change in physical appearance were observed for the five samples.

Other preliminary tests were conducted by exposing a few milligrams of the alloys to air on a balance to determine the weight gain due to oxidation at ambient temperature. No significant weight gain (> 1%) was observed.

For the preliminary compatibility tests between the metal alloys and water and the cooling fluid (Syltherm 800), a few milligrams of alloy was placed in a DSC test cell and a small drop of the liquid was placed on top. The water droplet did not wet the powder samples and no reaction was observed. The Syltherm 800 droplet wetted the powder sample but no exothermic was detected.

Reaction to water in an open cell

One

Conclusions and perspectives

Experiments undertaken with alloy La 0.9 Ce 0.05 Nd 0.04 Pr 0.01 Ni 4.63 Sn 0.32 show that this metal hydride does react neither with air, nor with water and also remains stable in case of thermal aggression or thermal over-heating. In any case, if there is a reaction, this one is not detectable.

The tiny increase of mass which have been observed at ambient air for activated samples, points out a light oxidation of the alloy. These conclusions are somehow unexpected, since some of these materials are known to be pyrophoric.

Obviously, all metal hydrides do not have a hazardous behaviour. Further experiments should be performed so as to identify those metal alloys which are the most reactive and to identify the cause of their reactivity (composition of the alloy, its state: activated or not, number of activation cycles). Further steps of the project will consist to study the impact of the presence of hydrogen in the intermetallic compound. Indeed, test have been carried out on intermetallic compounds, for which the last activation cycle was a desorption, so there were hydrogen free. These tests will be performed with the same intermetallic compounds in the Calvet C80 Calorimeter hydride, with circulation of hydrogen.

Moreover, it would be interesting to perform some tests with higher quantities of powder, so as to know if the quantity is not a hazard factor. Scale effect has to be investigated, having in mind that large quantities are handled in laboratories or factories. INERIS has now developed test procedures for metal hydrides safety assessment. These procedures can be shared in the framework of normative work, in order to have a common standard to test and rank metal hydrides hazardous behaviour.

Illustration 1 :

 1 DSC Calorimeter used for tests All tests were conducted in a Setaram 131 Differential Scanning Calorimeter with the following characteristics : Temperature range -170 to 700 °C Resolution0.4 µW Cell volume 30 µl CellStainless steel -300 bar Specific RMS noise0.008 %W/µl Time constant3 seconds Normal heat rate5 K/min

Table 3 :

 3 Main tests results -The five metal alloys at various stages of activation did not react to air, water, or the fluid Syltherm 800 at ambient temperature. -In air, the five samples did not react up to over 400 °C in open cells. -With water, the activated alloy sample of La Ni4 Mn reacted energetically in intensely starting at 140 °C in closed cells. The other samples displayed multiple peaks starting at about 170 °C. The thermograms of these tests are presented below. No exothermic reaction was detected with water in the open cell tests up to the boiling point of water. -No reaction with the fluid Syltherm 800 was detected in the closed cells and in the open cells before 330 °C. Energy : -496 (J/g) DSC n° 1184 Sample : CNRS Alloy 2R (15 cycles) + water (closed cell) INERIS n° 04 AZ 210 9/11

  1131 (J/g) DSC n° 1168 Sample : CNRS Actvated alloy+water (closed cell) INERIS n° 05 AS 293 Illustration 4: Thermograms of reaction with water in closed cell for each sample

Table 1 :

 1 4.63 Sn 0.32 03.7 La 0.9 Ce 0.05 Nd 0.04 Pr 0.01 Ni 4.63 Sn 0.32 153.8 La 0.9 Ce 0.05 Nd 0.04 Pr 0.01 Ni 4.63 Sn 0.32 305 Characteristic of the different studied samples.

	LaNi 4 Mn305.5
	La 0.9 Ce 0.05 Nd 0.04 Pr 0.01 Ni 4.63 Sn 0.32	3010.4

Open/Closed cellAtmosphereContact with other substanceHeat rate

	OpenAirNone5 K/min
	OpenAirWater2 K/min
	OpenAirSyltherm 8005 K/min
	Closed-None5 K/min
	Closed-Water5 K/min
	Closed-Syltherm 8005 K/min

3.4.2 DSC tests

DSC tests were carried out on all five metal alloy samples under the following conditions:

Table 2 :

 2 Conditions for DSC experiments of each sampleSamples were introduced in a cell, which was closed or opened, depending on the conditions of tests, as shown in the table above. Cells are made of stainless steel and contain a very limited quantity of powder (see illustration 3).

			2R	2R	3R	4R	La Ni4 Mn
			(04 AZ 209)	(04 AZ 210)	(05 AR 373)	(06 AE 528)	(05 AS 293)
	Number of cycles of adsorption-desorption	none15303030
	Test summary
	Reaction to air on the balance	Mass gain after 1 hour	+ 0,67 %No change+ 0,39 %-0,3 %-0,75 %
	Reaction to air in a pile	Temperature gain	No effectNo effectNo effectNo effectNo effect
	Reaction to water droplets on a pile	A drop of water placed on a pile of alloy	The water does not wet the alloy No reaction	The water does not wet the alloy No reaction	The water does not wet the alloy No reaction	The water does not wet the alloy No reaction	The water does not wet the alloy No reaction
	Reaction to Syltherm 800	A drop of Syltherm placed on a pile of alloy	The Syltherm wets the powder but no reaction	The Syltherm wets the powder but no reaction	The Syltherm wets the powder but no reaction	The Syltherm wets the powder but no reaction	The Syltherm wets the powder but no reaction
	Thermal stability in a closed cell	5 K/min rampe up to 500° C	No reactionNo reactionNo reactionNo reactionNo reaction
	Reaction to water in a closed cell	One small drop of water 5 K/min and rampe up to 500° C	Small reaction at 170 °C	Small reaction at 170 °C	Energetic reaction (907 J/g) starting at 165 °C	Energetic reaction (1101 J/g) starting at 160 °C	Energetic and intense reaction (1146 J/g) starting at 140 °C
	Reaction to Syltherm in a closed cell	One small drop of Syltherm 5 K/min and rampe up to 500° C	No reaction (same thermogram as Syltherm alone)	No reaction (same thermogram as Syltherm alone)	No reaction (same thermogram as Syltherm alone)	No reaction (same thermogram as Syltherm alone)	No reaction (same thermogram as Syltherm alone)
	Reaction to air Open cell	5 K/min rampe up to 500° C	Small reaction (173 J/g) at 270 °C	Reaction at 450 °C Mass gain + 0,001%	Multiple reactions starting at 240 °C Mass gain + 0,001%	Multiple reactions starting at 240 °C Mass gain + 0,002%	Energetic reaction starting at 160 °C (1734 J/g) Mass gain + 0,002%

La0.9Ce0.05Nd0.04Pr0.01Ni4.63Sn0.32

Within this context Axane, the French Atomic Energy Commission (CEA) -Hydrogen Technologies

Illustration 3: Illustration of sample cells

The overall results are reported in the table below.

Powdercells 4 Acknowledgements

The PLUSPAC project is supported by the French Ministry of Industry. With many thanks to Armelle FREZIER, from the INERIS Chemical Reaction Safety Laboratory, who performed the experiments.


Olivier Le Bihan
email: olivier.le-bihan@ineris.fr

Agathe Grossmith

Frantz Gouriou

Mikaël Renaud

Robin Aujay

Mikaël Reynaud

Contribution to knowledge of exposure in car passenger compartments

Keywords: habitacle, automobile, exposition, particules ultrafines, Nox

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Au cours de sa journée, un citadin répartit essentiellement son temps entre son domicile, son lieu de travail et les transports individuels ou collectifs. Il respire donc principalement les atmosphères de locaux fermés, que nous qualifions ici de « micro-environnements ».

La dose reçue à l'échelle d'une journée, est la somme des doses reçues dans ces différents microenvironnements, ce qui suppose la connaissance d'une part du temps passé dans chacun d'entreeux, et d'autre part du niveau et de la variabilité de la concentration en polluants.

A ce titre, et tout particulièrement en ce qui concerne le mode de vie citadin, les habitacles automobiles jouent un rôle important, puisqu'ils concernent une grande partie de la population, et qu'ils sont caractérisés par une forte exposition aux polluants issus du trafic. En effet, ce type de micro-environnement se situe dans le panache des émissions des autres véhicules. Parmi les composés issus du trafic automobile on trouve notamment le monoxyde de carbone, les oxydes d'azote et les particules.

La campagne a été menée du 28 juin au 9 juillet 2004. L'ensemble des moyens ont été basés sur le site du CERT AM, à Rouen.

-Dispositif

Véhicule

L'ensemble des appareils de mesure a été installé dans un véhicule utilitaire Renault Kangoo appartenant au CERTAM Une remorque adjointe à l'utilitaire a permis le transport du groupe électrogène de 3,7kW alimentant les appareils de mesure.

Le fonctionnement des divers appareils dans l'utilitaire et du groupe électrogène entraîne différents rejets qu'il a fallu prendre en compte.

Le groupe électrogène est effectivement une source de particules et de polluants gazeux. Pour supprimer leur impact, ses rejets ont été détournés tout à l'arrière de l'unité mobile. De plus, pour être certain qu'ils n'avaient aucune influence, nous avons pris en compte pour notre étude, uniquement les mesures réalisées en mouvement.

Les analyseurs d'oxydes d'azote présents dans le véhicule utilitaire sont des sources d'ozone. Pour protéger les expérimentateurs nous avons donc évacué ces émissions à l'extérieur du véhicule. Les autres rejets des appareils, non toxiques, n'ont pas fait l'objet d'une évacuation spécifique.

Prélèvement des échantillons

L'ensemble des résultats présentées dans notre étude est constitué de mesures réalisées sur l'air entrant dans l'habitacle, et non sur "l'air intérieur" au véhicule.

Ce choix se justifie en premier lieu par la contribution de l'ensemble des appareils de mesures présents dans le véhicule d'analyse à la pollution de l'habitacle. De plus, ce mode de prélèvement présente un autre avantage : il dépend très peu de la configuration du véhicule. Ainsi, les valeurs mesurées peuvent être comparées à celles d'une autre voiture. A l'inverse, des mesures directement réalisées dans l'habitacle sont spécifique d'un volume particulier, elles sont liées à une problématique plus complexe et font intervenir des paramètres tels que le nombre de personnes dans l'habitacle, leur comportement et l'équipement du véhicule (chauffage, climatisation, etc.).

Instrumentation

Les deux analyseurs de gaz utilisés au cours des roulages sont des analyseurs NO/NO2/N0x à chimiluminescence THERMO ENVIRONMENTAL INSTRUMENTS / MEGATEC , modèle 42-C.

Une mesure du CO a été assurée à l'aide d'un analyseur à Infira Rouge MAIHAK modèle UNOR 610.

En ce qui concerne la mesure des particules, nous avons mis en oeuvre l'impacteur basse pression DEKATI ELPI (7 nm -10 uni) ainsi que le compteur de particules CNC P-Track de TSI (20 nm -1uni).

-Résultats

Représentativité du point de mesure vis-à-vis de l'exposition du conducteur L'essai présenté ici a pour objectif de comparer les résultats obtenus avec le mode de prélèvement habituel, avec les caractéristiques de l'air directement respiré par le conducteur. Nous l'avons basé sur la mesure du NO.

Afin de disposer d'une source continue de NOx devant le véhicule, un véhicule essence non catalysé a été suivi, sur autoroute avec passages successifs au sein du même tunnel.

La comparaison entre air entrant et air intérieur montre : tout d'abord une période de "protection" où la concentration de l'air intérieur est inférieure à celle de l'air entrant ; puis une phase de "rémanence" pendant laquelle la pollution au niveau du conducteur persiste alors qu'il n'y a plus d'entrée de NOx dans l'habitacle. Ce phénomène perdure ici 3 mn 30 après la fin de l'épisode.

Figure 1 : Profils temporels de la concentration en NO dans l'air entrant et dans l'air intérieur sur un parcours autoroutier avee passages en tunnel. Figure 1 : NO tinte séries for fresh air and indoor air.

L'intégration des deux pics indique une surface identique pour chacun d'eux. Ainsi, les deux points de prélèvement ont été soumis à la même quantité de polluant. Ceci suggère que les deux mesures sont équivalentes en terme de quantification des doses reçues.

Ordres de grandeur

Le tableau ci-dessous résume les résultats généraux obtenus à l'aide du CNC, au cours de deux roulages, l'un sur l'autoroute AÏ3 (Rouen-Paris), l'autre sur le périphérique parisien. La figure 2 présente un exemple de mesurage de la concentration des particules. Ces résultats montrent une variabilité très importante des concentrations observées, d'une minute à l'autre (figure 4), voire même en fait, d'une seconde à l'autre.

Valeur maximum Valeur minimum

Le fait que l'autoroute représente majoritairement un espace « ouvert », implique que le niveau de fond est base, et l'exposition lié essentiellement à la présence dans un panache.

Dans le cas du périphérique, nous nous situons en milieu urbain, bien souvent encaissé voire semiclos (tunnel), en présence d'une densité de voiture beaucoup plus importante, et avec une proximité plus nette.

Ceci explique un minimum et un niveau moyen beaucoup plus hauts.

Influence de la distance vis-à-vis du véhicule précédent

Cet essai a pour but de caractériser les variations de l'exposition aux polluants dans l'habitacle d'une voiture, en fonction de la distance au véhicule la précédent.

Le véhicule suivi est une voiture de tourisme Citroen Picasso à motorisation Diesel Hdi 2 sans FAP.

Afin de simplifier au maximum les conditions de l'expérience pour éviter l'interférence de paramètres autres que la distance au véhicule émetteur. Ainsi, les mesures ont été réalisées en tunnel. En effet, les mesures réalisées en tunnels sont beaucoup moins soumises aux facteurs de variation tels que le vent. Par ailleurs, pour limiter l'influence du trafic automobile, l'essai a été réalisé entre 23h30 et 01h30 du matin, pendant une période de trafic réduit.

Figure 3 : Exposition aux particules (7 nm -10 um) mesurée par l'ELPI pour différentes distances au véhicule émetteur. En passant d'une distance de sécurité de 1 à 2 bandes on diminue de façon significative (réduction de 2/3) l'exposition en habitacle.

Au delà de 2 bandes, l'augmentation de la distance de sécurité est sans effet sur l'exposition aux particules. Ceci est probablement à associer au fait de se trouver dans un tunnel.

Il est à noter que la distribution en taille mesurée par l'ELPI ne fait pas apparaître de déplacement du diamètre médian, au fur et à mesure qu'augmente la distance.

Figure 2 :

 2 Figure 2 : Profil temporel de la concentration en nombre en habitacle lors d'un parcours sur le périphérique parisien (résultats moyennes sur 60 s).Figure 2 : example of particle concentration tinte série during thé «périphérique » trip (60s average)

Figure 2 :

 2 Figure 2 : Profil temporel de la concentration en nombre en habitacle lors d'un parcours sur le périphérique parisien (résultats moyennes sur 60 s).Figure 2 : example of particle concentration tinte série during thé «périphérique » trip (60s average)

  Figure 3 : Exposition aux particules (7 nm -10 um) mesurée par l'ELPI pour différentes distances au véhicule émetteur.Figure 3: Exposure to particles (7nm-10 pm) measured with ELPIfor three distances between thé target and thé source.

Figure 4 :

 4 Figure 4 : Granulométries moyennes en montée pour différentes distances (diamètre en um) Figure 4 : size distribution for three distance separating thé target and thé source La Citroën Picasso a été suivie à trois distances différentes : l'équivalent d'une, deux et trois bandes de signalisation autoroutière, soit environ 33, 66, et 100 mètres. Pour chacune de ces distances, six passages ont été effectués, dont trois en montée (fonctionnement à pleine charge) et trois en descente (charge partielle).

Remerciements

Les auteurs remercient tout particulièrement le Minstère Français de l'Ecologie et du Développement Durable (MEDD), et la région Haute-Normandie (Programme TOPAASE) pour leur aide financière.


Isabelle Zdanevitch
email: isabelle.zdanevitch@ineris.fr

Serge Collet

Martine Meyer

Jacques Auvray

Ambient air measurements related to traffic : évolution of VOCs over three years

Keywords: greater Paris area qualité de l'air, trafic, COV, Région Parisienne

Influence of traffic émission on air quality in European cities has widely been studied. Nevertheless, measurement campaigns are usually limited. We présent hère a set of VOC measurements which has been cottected during 5 to 6 campaigns each year over three years. Ambient air is sampled outside vehicles, inside thé traffic. Evolution of the concentrations both in urban and rural air over thé 3 years are discussed, compound by compound, and compared to data from literature. Influence of traffic on concentrations is obvious. The major fînding is that thé concentrations of pollutants related to traffic hâve been decreasing between 2003 and 2005, specially in urban atmosphères, and in a lesser way, in rural areas. Keys-words : air quality, traffic, VOCs,

Introduction

Influence of traffic émission on air quality in European cities has widely been studied. Nevertheless, measurement campaigns are usually limited, in thé number of pollutants or in thé time scale. We présent hère a set of atmospheric measurements of volatile organic compounds which has been collected outside a car, driving in thé traffic, during 5 to 6 campaigns each year between 2003 and 2005. Ail thé parameters: compounds, sampling and analytical techniques, locations, remained thé same over thé three years, allowing us to study thé évolution of concentrations. This évolution is discussed for urban and rural air, and values are compared to data from literature.

-Expérimental

Outside air inlet is fixed on front trunk of thé car, near thé car air inlet. A Teflon tubing goes to thé inside of thé car, where différent apparatus are connected. Sampling is done while thé vehicle is moving, on public roads, with two différent routes : one is typically urban, most of thé journey takes place on thé Parisian Périphérique (motorway around Paris, limited speed 80 km/h), thé other one is semi-rural, in thé south-west of greater Paris area (2 lanes roads, limited speed 90 km/h except in thé villages : 50 km/h). The same air flow is split to thé différent sampling Systems. The overall sampling time is around three hours.

The major VOC are : benzène and toluène, MTBE, 1,3-butadiene, formaldehyde, phénol, naphtalene. Other compounds of thé same familles (BTEX, aldéhydes and PAH) are analysed in thé same time, but will not be discussed hère.

Aromatic hydrocarbons and MTBE are sampled by pumping thé air through Carbotrap 300™ glass tubes, loaded with Carbotrap/ Carbosieve S III adsorbents. The sampled volume is 3,6 litres. Tubes are extracted by thermal desorption on a Perkin Elmer Turbomatrix, and analysed by GC/FID. 1,3-butadiene is sampled in evacuated Silcocan™ canisters of 6 litres. Extraction and analysis are performed within thé following week. 2 litres of air from thé canisters are trapped on Carbotrap/Carbosieve Perkin Elmer tubes. Tubes are thermally desorbed and analysed by GC/FID.

Formaldehyde is sampled by pumping on SEP-PAK™ : DNPH-silica gel cartridges. Sample volume is 36 litres. Extraction is done by solvent desorption. Analysis is done by HPLC with UV détection).

Phénol is sampled on 2-zones solid adsorbents of ORBO type; two tubes are placed in séries. Sampling volume is 100 litres. Desorption of each individual zone is done by NaOH 0,1 N. Analysis is performed with HPLC with fluorescence détection at 274/298 nm.

Polycyclic aromatic compounds (PAH) are sampled on quartz membranes + XAD-2 resin. Sampling volume is 275 litres. Extraction of supports taken together is done by ultrasonic bath, then extract, is concentrated. Analysis is done by HPLC/UV fluorescence with spécifie PAH wavelengths. On thèse samples, we only detect thé 6 lighter PAH : naphtalene to fluoranthene.

-Results and discussion

We présent hère thé results of 16 measurement campaigns, distributed over thé period March 2003 -November 2005. "ZERO" concentrations are lower than quantification limits.

Benzène

Figure 1 gives thé benzène concentrations for urban and rural journeys.

The fïrst observation is that benzène concentrations tend to decrease since March 03. This fact has been reported by several authors (Simon et al, Stemmler et al), as well as by thé French air quality network for thé greater Paris area "AIRPARIF". This decrease is due to thé réduction of benzène in gasoline, and, like for thé other VOC's, to thé généralisation of exhaust catalysts on cars, since 1993 for gasoline-fuelled cars, and 1997 for diesel-powered cars. Only thé last campaign -November 2005 -shows a slightly higher value than thé previous ones. There has been a pollution épisode at this time : AIRPARIF measurements on thé edge of thé Périphérique at Porte d'Auteuil, on thé day of thé campaign, show values which are consistent with those we measured in thé traffic.

Second fact is that ail urban concentrations except one, taken inside thé traffic, exceed thé future European Limit Value to be attained in 2010, of 5 [xg/m 3 (EC Directive 2000/69/EC). This limit value is an annual mean. Fortunately, benzène concentrations are lower at night, and also lower in areas with less cars, like quiet streets and residential areas, so thé mean daily exposure, for a citizen, generally fulfils this limit value.

On the contrary, nearly all our benzene measurements in the rural area comply with the French Air Guideline of 2 (xg/m 3 (Décret n° 98-360 du 6 mai 1998, JORF 13 mai 1998). The decrease in concentration with time is not so obvious as for urban air, because values are lower. In fact, rural benzène concentrations were sometimes lower than our quantification limit. As for benzène, we see a overall tendency to decrease with thé time since March 03. The stable values over thé last year need to be confirmed. They could probably be due to thé opposite effect offleet renewal with cars emitting less pollutants, and thé increase of traffic, and traffïc jams, in Paris and doser suburbs.

Toluene/benzene ratios

Table 1 gives thé toluene/benzene ratio for urban air samples. Generally, for urban air sampled in cities, with a BTX pollution coming from thé traffic, thé toluene/benzene ratio is in-between 2 and 3. It is lower when thé air mass is aged : in a Greek city, at 50 meters above thé traffic, this ratio is in-between 0.7 and 0.97 (Pilidis and al). Hère, sampling is done doser to thé source : thé car exhaust, and there is no time for thé pollutants to react with thé radicals présents in thé air. Therefore, toluène concentrations are higher than in an older air mass.

Other pollutants

Table 2 gives thé concentrations in MTBE and 1,3-butadiene.

For MTBE, urban concentrations vary widely from one campaign to another : from 5 to 32 }xg/m 3 . Rural values are more constant, and, like benzène and toluène, much lower than in urban area: they vary from zéro (concentration under quantification limit) to 6 [Ag/m 3 . There is no obvious season effect on thé higher urban concentrations. This compound, which is an additive in gasoline, is not very often measured in Europe. Mean weekly values reported for Helsinki (Hellen et al) are lower than 2 3 For 1,3-butadiene, concentrations are low, even for urban air. Values are lower than 2 |j-g/m 3 , except for two cases in October 03 and November 05 : for thé latter, it is thé same behaviour as benzène, toluène and MTBE. Thèse values, though being measured inside thé traffic, fall within thé English Air Quality Objective of 2,25 jAg/m 3 as an annual mean (UK National Air Quality Strategy). Rural concentrations are ail lower than 1 }jig/m 3 . There is no obvious season effect, though butadiene concentrations should be lower in summer due to thé réaction of this compound with ozone (Liu et al). There is no obvious decrease effect either, except between October 03 and February 05, but we hâve encountered higher values since then.

Figure 3 gives thé concentration for formaldehyde. Except in January and November 05, for which urban concentrations are relatively high, urban and rural concentrations show thé same tendency, and rural concentrations are 2 to 3 times lower than urban concentrations. Values are generally higher than thé mean value measured in Paris in 2003, probably at background sites : 4,3 jig/m 3 (LCPP). This means that thé source is anthropogenic and urban. Concentrations are lower in summer because of reactions with ozone, in air and during sampling, which causes an underestimation in formaldehyde. Figure 4 gives thé concentrations for phénol. This poUutant is not often measured in ambient air and concentrations are generally low. Hère, we report concentrations between O (below quantification limits) and 2 (j,g/m 3 . Once again, urban values are higher than rural concentrations, and they both tend to decrease with time, especially for urban values. There are little data available on phénol in ambient air. Inchem monograph cites values in Paris (1978Paris ( to 1985) ) from 0,7 to 8 jj,g/m 3 . Our measurements, though taken inside thé traffic, do not show so high values.

8 1 - o O '' O-o. "• A -• • --Rura l -O-Urbain i-~r V i- ssssssssssss Date campagne
Figure 4 : Figure 4 concentrations en phénol relevées sur les 16 campagnes (urbain + rural) phénol concentrations for thé 16 campaigns (urban + rural) concentrations en naphtalène relevées sur les 16 campagnes (urbain + rural) naphtalene concentrations for thé 16 campaigns (urban + rural)

1,5 1 i 6 V • -• -o. -•" ^~-O. -• • --Rura l -O -Urbain
Figure 5 gives thé concentrations for It is thé lighter of thé PAH, therefore thé one which will hâve thé closest behaviour to thé VOCs. As for thé aromatic compounds, we see clearly a decrease since Mardi 2003, but this decrease has been going on continuously over thé last year.

There is an increasing number of diesel engine cars in France : more than half thé new cars sold nowadays, and ail thé light and heavy duty vehicles, are diesel powered. The particulate matter and thé PAH in thé air should therefore be increasing. The observed decreasing tendency can be explained by thé benefït of fleet renewal with new technologies (Filter trap, ...) able to decrease thé PM and gas émissions.

Conclusion

For ail thé pollutants that we presented hère, influence of traffic as one of thé major sources is obvious : rural concentrations are far lower than urban values. Though our measurements are taken right in thé traffic, concentrations for several compounds are rather low compared to some of thé published data. It is directly connected to an improvement in air quality in a large city like Paris.

The major finding is that thé concentrations of most pollutants hâve been decreasing dramatically between 2002 and 2004, despite an increase in traffic, specially in urban atmosphères, and to a lesser extend, in rural areas as well. There are several causes : réduction of benzène in gasoline, improvement of engines, limitation of émissions thanks to catalysts, and renewal of thé car fleet.

Only formaldehyde, MTBE and 1,3-butadiene do not show this decrease, probably due to an initial low émission rate of traffic.

Références

Figure 1 :

 1 Figure 1 : Figure 1 :

  Figure 2 : Figure 2 : Toluène

Figure 3 :

 3 Figure 3 : concentrations en formaldéhyde relevées sur les 16 campagnes (urbain + rural) Figure 3 : formaldéhyde concentrations for thé 16 campaigns (urban + rural)

  Figure 5 : Figure 5

  Figure2gives thé toluène concentrations for urban and rural journeys.Toluène concentrations are quite high in urban air : they vary between 32 and more than 120 Such values hâve been reported for thé same type of sampling in Birmingham (Leung & Harrison). Rural concentrations are generally in between 5 and 15 (Ag/m 3 , which is slightly higher than other European values (Keymeulen et al, Schneider et al) but thé sampling hère is done in thé "rural" part of thé greater Paris area, therefore a small influence of thé city is possible.

-• --Rura l -O--Urbain Date campagne concentrations en toluène relevées sur les 16 campagnes (urbain + rural) toluène concentrations for thé 16 campaigns (urban + rural)

  AIRPARIF (2005): «Bilan de la qualité de l'air en Ile de France en 2004». URL : http://www.airparif.asso.fr/airparif7pdf/Bilan_2004 _paris_idf.pdf CHANG C.C., LO S.J., LO J.G., WANG J.L.(2003) : "Analysis of methyl ter-butyl éther in thé atmosphère and implications as an exclusive indicator of automobile exhaust". Atm. Env.. vol 37, p 4747 HELLEN H., HAKOLA H., LAURILA T., HILTUNEN V.,KOSKENTALO T. (2002): "Aromatic hydrocarbon and methyl tert-butyl éther measurements in ambient air of Helsinki (Finland) using diffusive samplers". Sci. Total Env.. vol 298, p. 55 INCHEM (International Programme on Chemical Safety) : Environmental health criteria 161. Phénol. WHO Library Cataloguing in Publication Data. ISBN 92 4 157161 KEYMEÛLEN R., GORGENYI M., HEBERGER K., PRIKSANE A., VAN LANGENHOVE H. (2001) "Benzène, toluène, ethyl benzène and xylenes in ambient air and Pinus sylvestris L. needles: a comparative study between Belgium, Hungary and Latvia". Atm. Env.. vol 35, p. 6327 LCPP : Laboratoire Central de la Préfecture de Police, & LHVP : Laboratoire d'Hygiène de la Ville de Paris : « Bilan 2003 de la qualité de l'air en région parisienne. Synthèse ». URL : http://www.prefecturepolice-paris.interieur.gouv.fr/documentation/dossiers/labo_bilan_2003/qualite_air 2003.pdf LEUNG P.-L., HARRISON R. M. (1999) : "Roadside and in-vehicle concentrations of monoaromatic hydrocarbons". Atm. Env.. vol 33, p 191 LIU X., JEFFRIES H. E., SEXTON K. G. (1999) : "Hydroxyl radical and ozone initiated photochemical reactions of 1,3-butadiene". Atm. Env., vol 33, p 3005 PILIDIS G., KARAKITSIOS S. P., KASSOMENOS P. A. (2005) : " BTX measurements in a medium-sized European city". Atm. Env.. vol 39, p 6051 SIMON, V.; BAER, M.; TORRES, L.; OLIVIER, S.; MEYBECK, M.; DELLA MASSA, J. P. (2004) : "The impact of réduction in thé benzène limit value in gasoline on airborne benzène, toluène and xylenes levels". Sci. Total Env.. Vol 334-335, p 177 SCHNEIDER, P., GEBEFUGI I., RICHTER K., WOLKE G., SCHNELLE J., WICHMAN H.-E., HEINRICH J., INGA Study Group (2001) : "Indoor and outdoor BTX levels in German cities". Sci. Total Env.. vol 267. p. 41-51. STEMMLER K., BUGMANN S., BUCHMANN B., REIMANN S., STAEHELIN J.(2005) : "Large decrease of VOC émissions of Switzerland's car fleet during thé past décade: results from a highway tunnel study". Atm. Env.. vol 39, n°6, p 1009 UK National Air Quality Strategy, Air Quality Objectives : for 1,3-butadiene, an objective of 2.25 ug/m 3 , measured as a running annual mean, was to be achieved in 31 December 2003


M Cauvin

T Verdel

R Salmon

C Didier

Mapping Expert Uncertainties or Confidence Level in Mining Risk Prevention Plans

Mining Risk Prevention Plans have been developed in France in order to deal with "Post-Mining" issues in a rapid and operational way. This inevitably implies that the final result of those risk analyses might contain a significant part of uncertainty. The study presented herein introduces a framework and some tools that allow experts to express the confidence they have in their evaluation and raise the main difficulties they face in their daily work.

Introduction

Many countries are now facing problems related to abandoned mines. The persistence of residual voids or the existence of open pits may generate disorders of several kinds: surface instabilities, surface flooding, noxious gas emission, severe environmental impacts, etc. Those disorders may have serious consequences on the populated mining areas. They also strongly influence the land use management of the concerned areas. In order to post and manage properly those hazards and risks, French Authorities have developed a technical and administrative powerful tool: the Mining Risk Prevention Plans (MRPP). MRPP aim to identify the most sensitive areas subject to "post mining hazards" and to define technical and regulation rules able to manage the principles of the future urbanism development on surface [START_REF] Didier | The MRPP: A powerful operational regulatory tool to prevent and manage post-mining risks[END_REF].

As defined in the edicts n°95-1089 of October 5 th 1995 and n°2000-547 of June 16 th 2000 of the French law, a MRPP has to contain:

1. a notice presenting the region being studied, the nature and the importance of the hazards that are likely to appear, as well as their probability of apparition and their consequences, given the state of knowledge; 2. one or several graphical documents mapping hazards zones; 3. a regulatory zoning plan defining homogeneous zones in terms of prohibitions, instructions or recommendations concerning land use, for both existing and future projects. In order to provide those 3 items and to deal with the regulatory constraint, MRPP are usually drawn up in 4 main phases [START_REF] Ineris | L'élaboration des Plans de Prévention des Risques Miniers, Guide méthodologique[END_REF], summarized in Figure 1.

Identification of the main problems encountered while elaborating a MRPP

MRPP have been developed in the context of the difficult management of the "Post-Mining" phase, the issues of which consist in posting and managing various risks likely to appear in numerous old mining sites spread in the whole French territory, at short notice and with limited financial and human resources. In such a context, MRPP have been developed to be rapid and operational tools for both population and Authorities. Therefore the philosophy of MRPP is to elaborate expert evaluation with available knowledge and to limit expensive investigations. The hazard assessment is thus mainly based on qualitative studies performed by experts using data collected in the field or in the various archives. As a matter of fact, the final result of the risk assessment might contain a significant part of uncertainty.

Working given the state of knowledge implies for the expert in charge of the evaluation to be limited by the quality of the information he can collect in the field or in archives. He usually has to face problems concerning the reliability of the mining maps (incompleteness, bad adjustment in comparison to surface, etc.), the informal nature of several data (oral statements, newspaper articles, etc.) or the difficulty to analyse events that occurred in the past (past collapse that is no more visible on surface at the time of the study, etc.).

The choice of elaborating simple (not simplistic) and rapid evaluations based on expert opinion implies to privilege qualitative methodologies of risk analysis rather than strong and complex modelling. Methods used by experts are principally based on experience rules, rules of thumb or are built on hypotheses that are sometimes very strong. The problem relies here in the degree of reliability of the methods being used and in the truth of the hypotheses that have been made.

Similarly, it is very difficult to deal with the regulatory request for expressing the probability of occurrence of hazards, introduced in the edicts n°95-1089 of October 5 th 1995 and n°2000-547 of June 16 th 2000 of the French law. This probability, denoted as susceptibility or predisposition is usually qualified in different levels: low, medium or high.

Information phase

Identifying, locating and mapping the potential sources of hazard, from the study of all available information, collected on-site or in the various archives

Hazard evaluation phase

Mapping the hazard areas and characterizing them in several hazard levels according the intensity and the probability of occurrence of the feared phenomena

Factor assessment phase

Drawing

Proposals for the integration and the representation of uncertainties in MRPP

Hypotheses and steps of work. In this study, a methodology has been built in order to both deal with the problems that have been presented before and respect the concept of MRPP as a rapid and operational tool. This methodology may be presented in three steps, each of which is aimed at answering a precise question:

1. Does it exist on a specific location of the area being studied a potential source of hazard? 2. Assuming the existence of this source of hazard, can it generate a disorder or a harmful effect on surface and what is the reliability of this result ? 3. How to reduce or at least mitigate the risk?

Concerning the existence of a source of hazard. The first question, concerning the existence of potential sources of hazard, is basically relative to the confidence or trust of the expert regarding the data he collected. In the context of MRPP, concerning for example the problems of surface instabilities, the sources of hazard are clearly the old mining infrastructures (underground workings, shafts, etc.).

For the most recent mines, during the phase of its closure, operators were asked by the French Authorities to compile all the information about the workings, including the mining maps. However these maps may be of different qualities, incomplete or even false. Some maps have been drawn before the end of the mine and the real working limits may extend beyond the presumed ones. On the contrary some working areas may be mapped although they remained at a planning stage and they obviously do not contain any underground voids. On some other maps, pillars can be mentioned as "blasted" but numerous residual underground voids may still remain today, as for example in some old mining workings of the iron ore district of Lorraine, France.

The problem is far more critical for the older mines. The extraction have often been small scaled, chaotic and made by craftsmen. Maps are, most of the time, unusable for a purpose of risk analysis (inaccuracy, bad adjustment of maps with regard to surface, distortion) or they are even non-existent! Therefore, experts have to base their studies on indications of workings, as geology, existence of old surface collapses, oral statements, etc. Where ore deposits exist or where a surface collapse occurred, mining workings might have been developed. It is thus possible that sources of hazard still exist today in these sectors.

The confidence an expert can have in the real existence of a source of hazard is thus dependent on the quality of the source of information he used to identify it. It appears really interesting to characterize each of the information sources by a confidence level or an index of existence related to the probability that a source of hazard really exists in a given area, taking into account the source of information that allowed to identify this one. The higher this probability, the more reliable the information and so the more confidence we will have about the existence of a structure likely to generate an accident. Such an index may for instance be determined by a committee of experts used at drawing up the MRPP. An example is given in Table 1. No mining map available Doubt on the nature of the surface collapse 1 NB : In this grid, the indexes of existence which are grouped into classes, concern the small sized underground voids that are able to generate sinkholes at surface. Values given are currently in phase of validation. (0 : 0-10% ; 1 : 10-30% ; 2 : 30-50% ; 3 : 50-70% ; 4 : 70-90% ; 5 : 90-100%).

Some precisions have to be established about the real signification of such a numerical index. An index of existence equal to 5 does not automatically mean that a hazard exists. It only means that the expert is confident concerning the fact that a mining infrastructure likely to create a disorder exists at a precise location of the studied area. The expert will have then to assess the hazard by using models and data about the geometry of the workings, etc. For instance, an index of 5 will be assigned to a 150m-depth mining gallery which is accessible and perfectly known. However, due to its important depth, the hazard due to this one is null.

Concerning the evaluation and the zoning of the hazard. The question about the existence of a source of a potential hazard leads automatically to another question: what can occur if this source of hazard really exists? In the example presented before, the answer was relatively obvious. We know, by experience, that if a small gallery located at an important depth collapses, the void will be filled in by the bulking of the overburden materials and no disorder will appear on surface. Even though it has not been explicitly expressed, this reasoning relies on a modelling process. The volume of the filled materials has been assessed in this case to be far greater than the volume of the initial void.

MRPP have been developed in order to deal with several mining-related risks: surface instabilities, water and soil pollutions, mine gas emission on surface, etc. The mechanisms of some of those risks are relatively easy to understand and modelling them is today possible, even using very simple analytical formulae. For the other kind of risks, we may hope that the researches that are currently undertaken will lead to the development of such models. Considering the risk of surface instabilities due to mining, simple models exist today to assess in an analytical form the amplitude of settlement, the height of caving for sinkholes, the slopes of the subsidence curves, the stresses acting on mining pillars, etc. Comparing the outputs of those models to threshold values, experts can conclude on the existence of a hazard (for instance if the height of caving is greater than the thickness of the overburden). They can also qualify a class of intensity for the hazard and zone it.

Modelling basically requires geometrical and mechanical data about the mining environment and the geological materials. In the context of the elaboration of MRPP, those data are sometime unknown and contain most of the time a significant part of uncertainty: the parameters are assessed from maps or expert hypotheses, the natural variability is not taken into account, etc. However, using back-analysis, expert knowledge, etc, the assignment of ranges of variation may be possible for each of the parameters of the models. Once those intervals of confidence are defined, methods as the Monte Carlo simulations may be used to express the uncertainty existing on the output of the model [START_REF] Cauvin | Modelling uncertainties in pillar stability analysis[END_REF]. Those methods allow experts to identify the parameters which have the greatest impact on the final result. They also allow to assess the probability that a certain variable (height of caving, stress acting on a pillar, safety factor of a slope) exceeds a certain threshold value (overburden thickness, pillar strength, security value (1.2; 1.5; 2; 3) respectively).

Concerning the spatial probability of occurrence of the hazard.

Following the previous results, the spatial probability of occurrence of a hazard may be introduced. It may be defined as the probability that two different events occur at the same time: a source of hazard exists at a given location (event E) AND an analysis leads to the conclusion, given the quality of the modelling, that this source of hazard can have consequences on people safety, on infrastructures or on ecosystems located in its vicinity (event A). The probability, denoted as P(OSp) and written in (1), is strongly dependant to the model that has been used in the analysis. Therefore, it corresponds more to the assessed hazard than to the real hazard. As the 'time' parameter generally lacks in the geotechnical models, P(OSp) may be seen as the percentage of chances that a given site will be affected one day by a hazard.

P(OSp) = Prob(A∩E) = Prob(E) x Prob(A/E) (1)
In order to evaluate the probability of occurrence of a hazard, [START_REF] Didier | Etablissement d'un Plan de Prévention des Risques liés à la présence d'anciennes carrières souterraines. Principes d'une analyse par configurations types[END_REF] combined two qualitative parameters. The meaning of those parameters seem to be very close to the ones introduced in (1). However, combining them in a qualitative way can add some confusion to the study. For example, two situations corresponding to very different conditions may coexist in a same class of 'probability of occurrence'. Therefore the understanding and the interpretation of the result of a risk analysis can become rather difficult.

Concerning the regulatory zoning plan. As indicated before, MRPP have to contain a regulatory zoning plan defining prohibitions, instructions or recommendations concerning land use, for both existing and future projects, as well as measures of prevention, monitoring and mitigation to adopt in risk areas. Some of the tools introduced in this study can be useful in the elaboration of these regulatory plans.

The mapping of the index of existence allows to identify areas where doubts exist regarding the real existence of a potential source of hazard. In those areas, investigations have to be undertaken in order to confirm the existence of mining workings. Regulatory plans are precisely aimed at defining such works that may be very important in a context of future land use management. The use of Monte Carlo simulations in order to assess the level of a hazard may allow to identify the parameters whose uncertainties have the greatest impact on the risk evaluation. Once those parameters are identified, experts can prescribe recommendations aiming at improving the knowledge about the most critical parameters. That will directly induce a better accuracy of the hazard posting.

Example

In this part, a fictitious example of an old mining site will be used in order to illustrate the different advantages of the tools that have been introduced. The mining map of this area is presented in Figure 2, left.

The mining site can be divided into 4 different areas. Pillars in zone 1 are mentioned as "extracted" but doubts exist regarding the quality of the pillar extraction that occurred long time ago. Zones 2 and 3 have been exploited by a room-and-pillar extraction method. Pillars in zone 2 are smaller than in zone 3. However even though the extraction seems to be partial, the rooms might have been filled in or collapsed. Zone 4, also exploited by a room-and-pillar extraction method, is accessible and has been visited. Although several disorders may be expected on the surface above these 4 zones, this study will only consider the sinkhole hazard. Table 2 introduces values for the indexes of existence assessed using Table 1 and Figure 2 (right) maps them.

The analytical model developed by INERIS [START_REF] Didier | Evaluation du risque d'apparition d'un fontis en surface : un modèle volumétrique probabiliste[END_REF]) can be used to assess whether sinkholes may reach the surface or not. In this study, the overburden thickness is assumed to be constant for the whole area and equal to 40m. In this example, the parameters having a strong influence in terms of risk evaluation are the seam height (h) and the width of the room (w). Uncertainties exist on those parameters as they are determined from expert hypotheses or mining maps. Ranges of variation can however be defined for those parameters and Monte Carlo simulations can be performed to assess the height of caving. Table 3 introduces for each zone the probability, denoted P(A), that the computed height of caving exceeds the overburden thickness. If we only consider the computed deterministic heights of caving, zone 3 seems to be the only zone at risk. Even though the 37.5m-computed value is smaller than 40m, the 5 first meters of overburden are usually considered as very weak layers that can not bridge over the caving arch. For the other zones, the caving should not reach the surface. However, if we take into account the uncertainties of the input parameters, it appears that numerous simulations (up to 48% for zone 1) lead to a height of caving greater than 40m. Using Tables 2 and3, the hazard due to sinkholes may be characterized for each of the 4 zones. The intensity of the phenomena is the same wherever in the mining site as the diameter of the feared sinkholes is expected to reach 10m maximum. Probabilities of spatial occurrence of the hazard, P(OSp), can be assessed for each zone by using Eq.1 (Table 3).

In zone 3, we are almost certain that some underground voids exist and the computed height of caving is very close to the thickness of the overburden. This zone is the most critical of the whole mining site and precisions should be brought about the factors existing on surface. This induces the necessity of a complete campaign of investigations. The regulatory plan should then define surveying or risk mitigating measures, or even a total prohibition from building new infrastructures.

A difference exists between the spatial probability of occurrence of hazard in zones 2 (13%) and 3 (35%) although the quality of the mining maps is the same. It can be explained by the fact that as the rooms are narrower in zone 2, their selffilling requires less material than in zone 3. The "likelihood" that a sinkhole reaches the surface is thus smaller in zone 2 than in zone 3. The situations are also very different in zones 1 and 3 even though the values of the spatial probabilities of occurrence of hazard are very close. In zone 1, the problem mainly relies on the existence of underground voids and investigations have to be carried out near the surface stakes. If the researches performed to prove their existence are unsuccessful, the existence of risk due to mining might disappear. NB : The computing has been made using a radius of the sinkhole chimney of 5m, a bulking factor of the materials of 1.3 and a natural angle of break of 40°. *: The width of the voids in zone 1 has been assumed to range between the width of one single room and the width of the group of {room+pillar(6m)+room} corresponding to the total span in case of a pillar failure.

Conclusions

Two tools have been introduced in this paper: the index of existence and the spatial probability of occurrence of a hazard. These may have a great importance in the context of risk analysis. Used separately, they are able to identify and highlight the major problems experts have to face during the drawing up of risk analyses. They may also bring a better formalism concerning the integration of uncertainties into MRPP. Used together, they allow a better characterization of the hazard in quantitative way. However, the real probability of occurrence of a hazard can not be assessed exactly yet. It can only be evaluated given the quality of modelling.

Research has now to be undertaken in this direction.

Figure 1 .

 1 Figure 1. The main phases of drawing up a MRPP.

Figure 2 .

 2 Figure 2. Mining site.

Table 1 .

 1 Example of a grid of values for the index of existence, ranging from 0 to 5.

	Room-and-pillar

Table 2 .

 2 Quality of the mining information related to the past mining workings.

	Zone	Description	Source of information	Main problems	Index of existence
	Zone 1	Pillars mentioned as "extracted"	Old mining map, low reliability	Some voids may exist underground 3 (60 %)
	Zone 2 Zone 3	Presence of room-and-pillars Presence of room-and-pillars	Old mining map, low reliability	Galleries might have been filled in ; might have been extracted Pillars might have collapsed or	5 (95 %)
	Zone 4	Presence of room-and-pillars	Direct visit on site		5 (100%)


O Le Bihan

S Geofroy

H Marfaing

R Aujay

M Reynaud

SIZE DISTRIBUTION AND NUMBER CONCENTRATION OF THE 10nm-20µm AEROSOL AT AN URBAN BACKGROUND SITE, GENNEVILLIERS, PARIS AREA

The purpose of this study is to quantify the exposure of people to the submicronic particles, and especially ultrafine/nanoparticules (< 100 nm) at an urban background site in the Paris area. Since 2003, two particle sizers have been used every year for a winter five weeks campaign.

INTRODUCTION

It is recognised that particles in urban air are responsible for serious health effects. The very small particles -ultrafines particules -are assumed to be important for the adverse health effects of particles [START_REF] Donaldson | Ultrafine particles[END_REF][START_REF] Li | Short-term inflammatory responses following intratracheal instillation of fine and ultrafine carabon black in rats[END_REF][START_REF] Salvi | Mechanisms of particulate matter toxicity[END_REF]. Thus, it is of main importance to characterize the exposure to submicrometer particles, in addition to the regulatory survey measurements (PM10). Size distribution and number concentration should be considered. France is especially concerned by this issue, due to the high percentage of diesel vehicles in the car fleet. This paper presents the results of a winter five weeks field campaign which has been carried out at the urban background station of Gennevilliers, Paris area from 2003 [START_REF] Le Bihan | Size distribution and number concentration of the 10-500 nm aerosol at an urban background site, Gennevilliers, Paris Area[END_REF] to 2006. In order to characterize the exposure to submicrometer particles, the size distribution and number concentration have been monitored in the 10 to 500 nm range. The statutory air survey parameters, and meteorological parameters have also been considered.

INSTRUMENTATION

A Scanning Mobility Particle Sizer (TSI) equipped with a long DMA and a TSI-3010 Particle Counter has been used. Each quarter of hour measurement was based on four 200 seconds scans, in the 10 to 500 nm range. The measurements were performed at the Gennevilliers urban background station (North-West of Paris). The monitoring site is a fixed station of the Paris Air Monitoring Network (AIRPARIF), and includes quarter of hour measurements of NOx, O 3 , SO 2 , PM10 (TEOM) and PM2.5 (TEOM).

RESULTS

Figure n°1 shows a view of the continuous measurements of the number of particles versus time. Ultrafine particles and non-volatile PM10 (TEOM 50°C) present the lowest correlation coefficient R (Table 2). These values (0.51, 0.41, 0.67) indicates a real but moderate correlation between these two parameters. The link would be better between the 100-500 nm range and PM2.5 (2005 : 0.83).

The winter average size distributions of the different campaigns (Figures 2 and3) show quite a similar shape : the dominant mode is centred in the 20-50 nm range that is to say that the ultrafine particles (< 100 nm) dominate the number size distribution and the total number concentration. This information confirms the correlation calculation (Table 2).

These results are in accordance to comparable studies [START_REF] Putaud | An European Aerosol Phenomenology : physical and chemical characteristics of particulate matter at kerbsite, urban, rural and background sites in Europe[END_REF].

SEASONAL COMPARISON

In figure 4 are compared the 2005 winter and summer average size distributions. As seen in Table 1 and figure 4, the summer average total number concentration is higher than the winter one. A more noteworthy observation is that the < 20 nm range seems to be characterized by an important mode, indicating high nucleation production of new particles.

DAILY CYCLE

A systematic daily mode has been observed at the Gennevilliers urban background site with a morning and an evening peaks. A link should be considered with trafic and heating, but also with the meteorological conditions (mixing layer height).

SIZE DISTRIBUTION ANALYSIS

A software has been developed in order to replace the multi-mode size distribution by a sum of fragments (unimode size distributions in the form of log-normal functions). An example of results is proposed in Figure 6 and table 3. A comparison between the measurements has been carried out for each size distribution obtained thanks to the fragmentation (Khi 2 assessment).

Measurement

It has been demonstrated that three modes are more or less permanent at the Gennevilliers site.

Fig. 2 :

 2 Fig. 2: average size distribution (winter 2003 -2005). Log scale.

Fig. 3 :

 3 Fig. 3: average size distribution (winter 2003 -2005).

Fig. 4 :

 4 comparison of the 2005 winter and summer average size distributions

Fig. 5 :

 5 Fig. 5: daily variations of the total number concentration during working days.

Fig. 6 :

 6 Fig. 6: fragmentation of the size distribution.

de particules entre 10 et 500 nm (p/cc)

  Fig. 1: Total number concentration versus time.Table1gives the total number 5% and 95% percentiles, and average. Table2gives the correlation (linear regression) between the total number concentration and other measurements (PM, gas).

	80 000
	70 000
	60 000
	50 000
	40 000
	30 000
	0 10 000 20 000 09/03/05 Nombre Number concentration Percentile 5% 14/03/05 19/03/05 24/03/05 29/03/05	03/04/05 Percentile 95% Average 08/04/05 13/04/05 18/04/05	23/04/05	28/04/05
	2003 (10-500 nm)	5 000	35 000	15 000
	2004 (10 nm -20 µm) 2 000	20 000	9 000
	2005 (10 nm -20 µm) 4 000	34 000	13 500
	Summer 2005	7 200	40 000	20 700

Table 1 :

 1 Total number concentration.

	Correlation R	10-100	100-	PM10	PM2,5	NO	NO 2	O 3
	N (10-500 nm)	nm	500 nm	TEOM	TEOM
	versus …			50°C	50°C
	2003	0.99	0.87	0.51	0.58	0.73	0.64	-0.50
	2004	0.99	0.91	0.41	0.37	0.81	0.88	-0.73
	2005	0.99	0.91	0.67	0.66	0.72	0.77	-0.58
	Summer 2005			0.64	0.67	0.68	0.84	-0.45

Table 2 :

 2 Correlation of the 10-500 nm number concentration versus PM and gas measurements.

Table 3 :

 3 fragmentation of the size distribution.

	Calculated	size
	distribution

ACKNOWLEDGEMENTS

This work is supported by the LCSQA. Thanks to Tatiana Macé (LNE) for technical collaboration on APS sizer. Thanks to Isaline Fraboulet and Martine Ramel.


F Mathé

O Le Bihan

H Marfaing
email: helene.marfaing@airparif.asso.fr

DEMONSTRATION OF EQUIVALENCE OF PM AUTOMATED MONITORING METHODS: RESULTS OF THE 1 ST MEASUREMENT CAMPAIGN ON A PARISIAN URBAN BACKGROUND AIR QUALITY STATION

Keywords: Demonstration of equivalence, Data Quality Objective, EU Directives, automatic monitors

The present study summarizes the results of a measurement campaign conducted in Paris suburbs (Bobigny -95) from January to March 2005, in the framework of Laboratoire Central de Surveillance de la Qualité de l'Air (LCSQA) activities. The main goal is to show that the methods tested (TEOM -FDMS from Thermo R&P and beta gauge MP101M-RST from Environnement SA) meet the Data Quality Objectives for PM 10 continuous measurements specified in the Air Quality Directive 99/30/EC, under conditions reflecting practical application in air quality monitoring networks. PM 2.5 continuous measurement feasibility has also been studied.

INTRODUCTION

One of the objectives of the European Directive 96/62/EC ("Air Quality Framework Directive", [1]) is to "assess the ambient air quality in Member States on the basis of common methods and criteria". The European Air Quality Directives ("Daughter" Directives) relate to limit or target values for specified atmospheric pollutants (SO 2 , NO/NO x /NO 2 , PM 10 , CO, C 6 H 6 , O 3 , Heavy metals and PAH). These specify the principles of the Reference Methods (RM) to be used for the measurement of ambient concentrations. In addition, they specify Data Quality Objectives that have to be met for the performance of measurement in matter of uncertainty (i.e.: ± 25% for PM 10 in the region of the appropriate limit value [2]), using Reference Methods which are Standard Methods produced by European Committee for Standardization (CEN).

A Member State (MS) when implementing the Directives should use the Reference Methods, but the Directives allow MS the possibility to "use any other method which it can demonstrate results are equivalent to the Reference Method". The European Commission has recently prepared a document describing principles and methodologies to be used for the demonstration of the equivalence of alternative (nonreference) measurement methods to the EN Standard Methods [START_REF]Demonstration of equivalence of ambient air monitoring methods[END_REF]. It is intended for use by laboratories to perform the tests relevant to the demonstration of equivalence of ambient-air measurement methods. Concerning PM 10 , the 1 st Daughter Directive specifies that measurements should be carried out using the Reference Method as defined in European Standard EN12341 [START_REF]Air quality -Determination of the PM 10 fraction of suspended particulate matter -Reference method and field test procedure to demonstrate reference equivalence of measurement methods[END_REF]. This method presents some disadvantages (high operating costs, time resolution of measurement limited to 24 hours, Directive reporting requirements cannot be met). That is the reason why automated monitors such as Tapered Element Oscillating Microbalance (TEOM) or beta attenuation analysers) are widely used by Air Quality Monitoring Networks for measuring continuous concentrations of particulate matter. The principal disadvantage of automated methods is the requirement to hold the inlet and filter at a temperature above the atmospheric temperature, leading to potential loss of (semi)volatile species such as ammonium nitrate and so to differences with the Reference Method. In order to avoid unrealistic data correction, french authorities have decided to study technical solutions developed by manufacturers aiming to reduce this loss of volatile components. The demonstration of the efficiency of such developments shall be done following the requirements of the European Document. The present study summarizes the results of a measurement campaign conducted by INERIS and Ecole des Mines de Douai in Paris suburbs (Bobigny -95) from January to March 2005, in the framework of Laboratoire Central de Surveillance de la Qualité de l'Air (LCSQA) activities. The main objective is to show that the candidate methods (CM) tested (TEOM -FDMS from Thermo R&P and beta gauge MP101M-RST from Environnement SA) meet the Data Quality Objectives for continuous measurements specified in the Air Quality Directive, under conditions reflecting practical application in air quality monitoring networks.

METHODOLOGY

The experimental site is located at Bobigny (95) in an urban background area (Fig. 1) and near an air pollution monitoring station from Airparif (Paris air quality network). The choice of site and time period of the year has been based on representativeness for typical conditions for which equivalence will be claimed, including possible episodes of high concentrations. These field tests shall be performed in which all methods are compared side-by-side (Fig. 2). A good accordance of both new technologies with Reference Method is observed. 2 importants points should be stressed:

-same exceedances number of daily limit value (50 µg.m -3 ) are detected by RM and CMs -there is no need of correction factors or terms for CMs A similar statement can be done for PM 2.5 measurements Concerning PM 10 , all results obtained during the Bobigny campaign for both of candidate methods under the configuration used fulfil all criteria of equivalence demonstration procedure: datasets are suitable (at least 20% of the results are greater than 25 µg.m -3 which is 50% of the daily limit value specified in the Daughter Directive)

between-instrument uncertainty is satisfying (1,9 µg.m -3 for MP-101M RST and 1,5 µg.m -3 for TEOM-FDMS for performance criterion of 3 µg.m -3 not to be exceeded), using equation (1) based on the differences of all 24-hour results of the instruments operated in parallel:

( )

n y y u n i i i bi 2 1 2 2 , 1 , 2 ∑ = - = (1)
Where: u bi is between-instrument uncertainty y i,1 and y i,2 are the results of parallel measurements for a single 24hour period i n is the number of 24-hour measurement results.

orthogonal regression line equations are respectively MP-101M RST = 0,96 x Reference + 1,09 and TEOM-FDMS = 0,95 x Reference -1,69 Slope and intercept are non significative according to statistical data treatment recommended in european document. Figure 4 and5 give shape of orthogonal regression line: expanded relative uncertainty at the level of daily limit value (50 µg.m -3 ) observed during the campaign (± 13,2% for MP-101M RST, ± 17,6 % for TEOM-FDMS) meets data quality objective of ±25% required by Directive 99/30/CE. Concerning PM 2.5 , similar good results are observed for TEOM-FDMS (In this assessment, a limit value for PM 2.5 of 35 µg.m -3 has been assumed following european recommendations [START_REF]Second position paper on particulate matter -Clean Air[END_REF]): 1 suitability of datasets (at least 20% of the results are greater than 17,5 µg.m -3 which is 50% of the assumed daily limit value) 2 Satisfaction concerning between-instrument uncertainty (1,9 µg.m -3 for TEOM-FDMS and 0,9 µg.m -3 for Reference Method for performance criterion respectively of 3 and 2 µg.m -3 not to be exceeded) 3 orthogonal regression line equation is TEOM-FDMS = 1,03 x Reference + 0,46 Figure 6 gives shape of orthogonal regression line: 4 expanded relative uncertainty at the level of the supposed daily limit value observed during the campaign (± 11,2%) meets data quality objective of ±25% (assumed to be the same as the one required by Directive 99/30/CE for PM 10 ).

CONCLUSION

This first field result based on a specific protocol is quite encouraging for equivalence demonstration of TEOM-FDMS and β-attenuation monitor MP101M-RST for PM measurement. These results need to be confirmed in 3 other sites at minimum, with other composition of ambient air or meteorological conditions, in order to assume that equivalence for equipment tested is valid anywhere else under ambient conditions. A similar campaign performed at Marseille (South of France) from January to April 2006 has given similar satisfying results. The key point now is the establishment of the final report on the equivalence demonstration of these studied methods, to be submitted to the European Commission. A generalization of equivalence claims, based on sharing other european experiences conducted with similar analysers should be considered

Fig. 1 :Fig. 3 :

 13 Fig. 1: sampling site situation Fig. 2: General view of apparatus Concerning particulate matter PM 10 and PM 2.5 , the gravimetric reference used was a Partisol Plus 2025 sequential sampler (Thermo R&P) collecting on 47 mm diameter, 2 µm pore size PTFE filters (Zefluor TM from Pall Corporation). The weighing procedure was conducted by INERIS according to requirements of European Standard EN 14907 [5], using a balance with a resolution of 10 µg in a temperature (20 ± 1°C) and humidity (50 ± 5% RH) controlled weighing room. The 2 candidate methods were TEOM-FDMS (PM 10 and PM 2.5 ) and beta monitor MP101M-RST PM 10 . All apparatus were duplicated et equipped with same US size-selective inlet. Sampling monitoring series lasted 70 days for a total of 194 validated individual measurements. The objective was to collect a minimum of 40 duplicated pairs of measurement results each averaged over at least 24-hour per comparison.

Fig. 4 :Fig. 5 :

 45 Fig. 4: Comparison of β-attenuation monitor with reference method (PM 10 24h values)

Fig. 5 :

 5 Fig. 5: Comparison of TEOM-FDMS with reference method (PM 10 24h values)

ACKNOWLEDGEMENT

The authors are grateful to the manufacturers (Environnement SA, Thermo R&P and its french representative Ecomesure) for their help during the campaign. This work was financially supported by the French Ministry of Environment (MEDD) and by the French Agency for Environment and Energy Management (ADEME).