EN 689:2018

Workplace exposure - Measurement of exposure by inhalation to chemical agents - Strategy for testing compliance with occupational exposure limit values

This European Standard specifies a strategy to perform representative measurements of exposure by inhalation to chemical agents in order to demonstrate the compliance with occupational exposure limit values (OELVs).
This European Standard is not applicable to OELVs with reference periods less than 15 min.

Exposition am Arbeitsplatz - Messung der Exposition durch Einatmung chemischer Arbeitsstoffe - Strategie zur Überprüfung der Einhaltung von Arbeitsplatzgrenzwerten

Diese Europäische Norm legt eine Strategie zur Durchführung repräsentativer Expositionsmessungen in Bezug auf die Inhalation chemischer Arbeitsstoffe fest, um die Einhaltung von Beurteilungsmaßstäben (OELVs) nachweisen zu können.
Diese Europäische Norm ist nicht anwendbar auf OELVs mit Referenzdauer von weniger als 15 min.

Exposition sur les lieux de travail - Mesurage de l'exposition par inhalation d'agents chimiques - Stratégie pour vérifier la conformité à des valeurs limites d'exposition professionnelle

La présente Norme européenne spécifie une stratégie pour effectuer des mesurages représentatifs de l’exposition par inhalation à des agents chimiques afin de démontrer la conformité aux valeurs limites d’exposition professionnelle (VLEP).
La présente Norme européenne n’est pas applicable aux VLEP dont les périodes de référence sont inférieures à 15 min.

Izpostavljenost na delovnem mestu - Merjenje izpostavljenosti pri vdihavanju kemičnih agensov - Strategija preskušanja skladnosti z mejnimi vrednostmi za poklicno izpostavljenost

Ta evropski standard določa strategijo za izvajanje reprezentativnih meritev izpostavljenosti kemičnim snovem zaradi vdihavanja z namenom dokazovanja skladnosti z mejnimi vrednostmi za poklicno izpostavljenost.

General Information

• Status: Withdrawn
• Publication Date: 08-May-2018
• Withdrawal Date: 13-Apr-2025
• ICS: 13.040.30 - Workplace atmospheres
• Technical Committee: CEN/TC 137 - Assessment of workplace exposure
• Drafting Committee: CEN/TC 137 - Assessment of workplace exposure
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Start Date: 10-Apr-2019
• Completion Date: 14-Apr-2025
• Ref Project: SIST EN 689:2018 - Workplace exposure - Measurement of exposure by inhalation to chemical agents - Strategy for testing compliance with occupational exposure limit values

Relations

• Replaces: EN 689:1995 - Workplace atmospheres - Guidance for the assessment of exposure by inhalation to chemical agents for comparison with limit values and measurement strategy
• Effective Date: 16-May-2018
• Merged Into: EN 689:2018+AC:2019 - Workplace exposure - Measurement of exposure by inhalation to chemical agents - Strategy for testing compliance with occupational exposure limit values
• Effective Date: 15-Jul-2018

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2018
1DGRPHãþD
SIST EN 689:1998
,]SRVWDYOMHQRVWQDGHORYQHPPHVWX0HUMHQMHL]SRVWDYOMHQRVWLSULYGLKDYDQMX
NHPLþQLKDJHQVRY6WUDWHJLMDSUHVNXãDQMDVNODGQRVWL]PHMQLPLYUHGQRVWPL]D
SRNOLFQRL]SRVWDYOMHQRVW
Workplace exposure - Measurement of exposure by inhalation to chemical agents -
Strategy for testing compliance with occupational exposure limit values
Exposition am Arbeitsplatz - Messung der Exposition durch Einatmung chemischer
Arbeitsstoffe - Strategie zur Überprüfung der Einhaltung von Arbeitsplatzgrenzwerten
Exposition sur les lieux de travail - Mesurage de l'exposition par inhalation d'agents
chimiques - Stratégie pour vérifier la conformité à des valeurs limites d'exposition
professionnelle
Ta slovenski standard je istoveten z: EN 689:2018
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 689
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2018
EUROPÄISCHE NORM
ICS 13.040.30 Supersedes EN 689:1995
English Version
Workplace exposure - Measurement of exposure by
inhalation to chemical agents - Strategy for testing
compliance with occupational exposure limit values
Exposition sur les lieux de travail - Mesurage de Exposition am Arbeitsplatz - Messung der Exposition
l'exposition par inhalation d'agents chimiques - durch Einatmung chemischer Arbeitsstoffe - Strategie
Stratégie pour vérifier la conformité à des valeurs zur Überprüfung der Einhaltung von
limites d'exposition professionnelle Arbeitsplatzgrenzwerten
This European Standard was approved by CEN on 2 March 2018.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 689:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions and abbreviations . 6
3.1 Terms and definitions . 6
3.2 Abbreviations . 7
4 General . 7
5 Occupational exposure assessment. 9
5.1 Basic characterization . 9
5.1.1 General . 9
5.1.2 Identification of chemical agents and other information required . 9
5.1.3 Review of workplace factors . 10
5.1.4 Estimation of exposure . 10
5.1.5 Decisions . 11
5.2 Sampling strategy. 11
5.2.1 Constitution of Similar Exposure Groups (SEGs) . 11
5.2.2 Specifying the measuring procedure . 12
5.3 Performing exposure measurements . 13
5.4 Validation of results and SEGs . 13
5.4.1 General . 13
5.4.2 Validation of measurement results . 13
5.4.3 Validation of SEGs . 14
5.5 Comparison of results with OELVs . 14
5.5.1 General . 14
5.5.2 Preliminary test . 15
5.5.3 Statistical test . 15
6 Report . 16
7 Periodic reassessment . 16
Annex A (informative) Assessment of exposure . 18
A.1 General . 18
A.2 Workplaces with constant conditions . 20
A.3 Shortened exposure at workplaces with constant working conditions . 20
A.4 Workplaces involving occasional exposure . 20
A.5 Stationary workplaces with irregular exposure . 21
A.6 Workers who move from a workplace to another with irregular exposure . 21
A.7 Workplaces with unpredictable, constantly changing exposure . 22
A.8 Outdoor workplaces . 22
A.9 Underground workplaces . 22
Annex B (informative) Occupational exposure limit values for compliance testing . 24
Annex C (informative) Simultaneous workplace exposure to several chemical agents . 26
C.1 General . 26
C.2 Tier 1: Exposure index (I ) . 26
E
C.3 Tier 2: Additive effect exposure index (I ) . 27
AE
C.4 Other approaches . 28
Annex D (informative) Exposure profile and sampling duration. 29
D.1 General . 29
D.2 Measurement for testing compliance with 8 h- OELV . 29
D.3 Measurement for testing compliance with short-term limit value . 34
Annex E (informative) Check of exposure measurements distribution, and identification of
exceptional exposure within the SEG . 35
E.1 General . 35
E.2 Graphical method . 35
E.2.1 Principle . 35
E.2.2 Plotting . 36
E.2.3 Example . 36
E.2.4 Examples of SEGs requiring further consideration . 37
E.2.4.1 General . 37
E.2.4.2 SEG consisting of two groups . 38
E.2.4.3 Some individuals with exceptional exposure . 39
E.2.4.4 Distributions appearing to be not lognormal. . 40
E.3 Statistical methods for the validation of SEGs . 41
Annex F (informative) Testing compliance with OELVs . 42
F.1 General . 42
F.2 SEG compliance test for at least six exposure measurements . 42

F.3 Decision . 43
Annex G (informative) Exposure calculation with a work shift longer than 8h . 45
Annex H (informative) Exposure below the limit of quantification . 46
H.1 General . 46
H.2 Principle . 46
H.3 Example . 46
H.4 Uncertainty . 49
H.5 Software . 50
Annex I (informative) Interval for periodic measurements . 51
Bibliography . 53

European foreword
This document (EN 689:2018) has been prepared by Technical Committee CEN/TC 137 “Assessment of
workplace exposure to chemical and biological agents”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by November 2018, and conflicting national standards
shall be withdrawn at the latest by November 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 689:1995.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Introduction
This European Standard deals with the measurement of exposure to chemical agents in workplace
atmospheres, and in particular with measurement strategy for comparing workers' exposure by
inhalation with occupational exposure limit values (OELVs). Other parts of management of exposure of
workers are not dealt with in detail in this European Standard.
Within this European Standard, compliance means that workers’ time weighted average workplace
exposure is below an OELV with a corresponding reference period. OELVs include legal values and
other numerical criteria (see Annex B).
Representative measurement of workplace exposure to chemical agents is difficult, because of the
variability of exposure. Processes and products affecting exposure are numerous. Different workplace
conditions can correspond to different generation rates, can involve a variety of chemical agents and
can therefore present specific exposure conditions. Exposure can be affected by the distance of the
exposed workers from emission sources; and parameters such as emission intensity, ventilation,
climatic conditions, seasonal variations and the controls applied can also have a very marked influence.
The spatial and temporal variabilities of exposure conditions are further enhanced by workers'
practices and activities themselves.
The sampling equipment introduces its own limitations, and the analytical steps add further difficulties
and uncertainties.
This European Standard is applicable for measuring procedures that fulfil the requirements of EN 482.
If a measuring procedure does not fulfil these requirements some parts of the procedure described in
this European Standard cannot be applied.
To assess the exposure of workers to chemicals and to state with certainty that it does not exceed the
OELVs (short-term or long-term) would require measurement of the exposure of every worker for
every working day. Unfortunately while this approach is possible for some agents such as ionizing
radiation, it is not feasible or practical for many chemical agents due to limitations of the measurement
techniques and costs.
The strategy described in this European Standard gives a procedure for the employer or other
stakeholders to overcome the problem of variability and to use a relatively small number of
measurements to demonstrate with a high degree of confidence that workers are unlikely to be exposed
to concentrations exceeding the OELVs. To reduce the number of exposure measurements, and
therefore the cost of assessment, personal air samples are collected among workers within similar
exposure groups (SEGs). A single measurement or even several measurements below the limit value can
be insufficient to reliably demonstrate compliance without using a statistical test like the one proposed
in this European Standard.
Respiratory protective equipment (RPE) is used to reduce the amount of the chemical agent that is
inhaled by the worker. However, this European Standard does not take into account the use and
effectiveness of RPE in testing compliance with the OELV.
Before any measurements are performed, it is essential for an appraiser to conduct a basic
characterization in order to collect relevant information on workplace factors, and the available
information on exposure in the workplace concerned. This includes information on variation of
exposure with time of day and season of the year, so that the measurement is representative.
If the basic characterization shows that exposure is probably higher than the OELV, then it is
recommended to reduce exposure by risk management measures (RMM) before measurements are
planned for compliance testing.
1 Scope
This European Standard specifies a strategy to perform representative measurements of exposure by
inhalation to chemical agents in order to demonstrate the compliance with occupational exposure limit
values (OELVs).
This European Standard is not applicable to OELVs with reference periods less than 15 min.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 482, Workplace atmospheres — General requirements for the performance of procedures for the
measurement of chemical agents
EN 1540, Workplace exposure - Terminology
3 Terms and definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1540 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
appraiser
person who is sufficiently trained and experienced in occupational hygiene principles, working and
measurement techniques, to conduct the part of the assessment they are performing according to the
state of the art
Note 1 to entry: The appraiser may be supported by a team of qualified persons.
3.1.2
exposure profile
description of the exposure variations to a chemical agent in relation to the definable series of activities
from the periods under consideration
Note 1 to entry: See Annex D.
3.1.3
similar exposure group
SEG
group of workers having the same general exposure profile for the chemical agent(s) being studied
because of the similarity and frequency of the tasks performed, the materials and processes with which
they work, and the similarity of the way they perform the tasks
3.2 Abbreviations
AM arithmetic mean
CAS chemical abstracts service
DMEL derived minimum effect level
DNEL derived no-effects level
EC number European community number
GSD geometric standard deviation
GM geometric mean
H hour
LOQ limit of quantification
OELV occupational exposure limit value
RPE respiratory protective equipment
RMM risk management measures
SD standard deviation
SEG similar exposure group
WS work shift
4 General
The assessment of occupational exposure to chemical agents based on air samples requires the
development of a strategy including different phases which shall be conducted by an appraiser.
The strategy consists of an initial workplace exposure assessment (described in Clauses 5 and 6) and
then periodic reassessment (see Clause 7). The initial workplace exposure assessment comprises
different phases:
— basic characterization of the workplaces;
— constitution of similar exposure groups;
— selection of a suitable measuring procedure;
— performing exposure measurements;
— validation of exposure measurement results and SEGs;
— comparison of results with OELVs;
— reporting of results.
The sampling strategy comprises the constitution of SEGs and the definition of measuring procedures. If
the initial workplace exposure assessment indicates non-compliance with OELVs for some SEGs, control
measures shall be implemented and a new initial workplace exposure assessment shall be conducted.
Following the initial workplace exposure assessment, periodic reassessments shall be conducted. When
significant changes occur at the workplace that may affect exposure conditions, the appraiser shall
decide whether a new initial workplace exposure assessment shall be conducted.
Figure 1 gives a schematic overview of the procedures described in this European Standard.

Figure 1 —Schematic overview of the strategy
5 Occupational exposure assessment
5.1 Basic characterization
5.1.1 General
Prior to exposure measurements, the workplace and the related exposure profile under consideration
shall be considered.
The basic characterization of exposure determinants is in three steps:
— identification of chemical agents and other information required;
— review of workplace factors;
— estimation of exposure.
All the information collected during the basic characterization shall be used to:
— decide whether measurements are necessary or not (see 5.1.4);
— constitute the different SEGs.
Use of exposure monitoring devices able to give an instant feedback to the user, either as a single or a
continuous reading (so called direct-reading instruments), can give valuable information about
approximate exposure level, the exposure pattern, and spatial, time and worker variability of the
exposure.
5.1.2 Identification of chemical agents and other information required
The preparation of a list of all chemical agents in the workplace and the relevant information concerned
is an essential first step to the identification of the potential for hazardous exposure. The safety data
sheets and other available information are useful to establish the list. The list shall include any of the
following:
— raw materials, primary products, impurities, intermediates, final products, reaction and process
products and by-products, etc;
— the individual chemical agents, identified with chemical registration numbers (e.g. CAS#, EC#);
— hazardous properties, classification and labelling;
— appropriate OELVs depending on the goal of the assessment (see Annex B);
— whether dermal and oral exposure of the chemical agents is relevant (this European Standard only
deals with measuring inhalation exposure, but knowledge of other routes can be important in the
management of exposure);
— additional information such as amount used, vapour pressure, temperature, saturation
concentration, dustiness, etc.
5.1.3 Review of workplace factors
The work processes and procedures shall be evaluated to gauge the exposure and the exposure profile
to chemical agents by a detailed review of workplace factors, such as:
— work organization: activity, task, job title, work shift system, job functions, etc.;
— processes and techniques (type of processes, temperature, pressure, etc.);
— workplace layout and configuration, including confined spaces, open air, etc.;
— safety precautions and procedures (restricted area, etc.);
— cleanliness and tidiness of workplace;
— ventilation installations and other forms of engineering control and any information on their
performance;
— emission sources and locations of high concentrations ;
— periods, frequencies and durations of exposure taking into account variation of exposure with time
of day and season of the year;
— work load;
— worker behaviour, or
— activity or production rate indicators.
5.1.4 Estimation of exposure
The appraiser shall collect available information to allow reliable estimates of the exposure of the
workers. Annex A gives guidance on this.
Possible sources of information include:
— earlier measurement results in this workplace, including from direct-reading instruments;
— measurement results from comparable installations or work processes (databases, literature, etc.);
— calculations based on relevant quantitative information;
— exposure modelling.
A decision that an exposure is much lower than the OELV should be made, for example in the following
cases:
— the release capability is low because of the working conditions and the substance properties (e.g.
low vapour pressure, high boiling point with low processing temperature, low dust-forming
behaviour);
— the operational conditions cannot give rise to the formation of aerosols;
— only small quantities are used;
— only low emissions are possible, for example because of small source surfaces or short activity
duration (<15 min).
The estimates shall be used to make a decision in 5.1.5.
The estimates shall also be used to verify whether the sampling and analysis techniques that are
proposed for the measurements are adequate.
5.1.5 Decisions
The results of basic characterization lead to one of the following decisions:
— the exposure is higher than the OELV (non-compliance); then the appraiser shall report this (see
Clause 6) and advise on a programme to reduce exposures, using RMM, before making
measurements to test compliance;
— the exposure is well below the OELV (compliance); then the appraiser shall decide if measurements
are necessary or not. If measurements are unnecessary, the appraiser shall report this (see
Clause 6) and advise on a reassessment (see Clause 7);
— the available information on exposure is insufficient to decide on compliance with the OELV; then
the appraiser shall continue to develop a sampling plan (see 5.2).
5.2 Sampling strategy
5.2.1 Constitution of Similar Exposure Groups (SEGs)
In practice it is usually not possible to measure the exposure of each worker during each working day.
In order to obtain quantitative data from exposure measurements that allows assessment of compliance
with OELVs, an effective approach shall be taken that allows the most efficient use of resources.
This approach, based on the observation of working conditions, permits measurement of exposure of a
small number of workers belonging to a SEG for comparison with OELVs. Where exposure
measurements on some workers of the SEG indicate that the OELVs are met (compliance), then it is
considered that this is so for all workers in the SEG.
The SEG shall be constituted using information on the profile of exposure and duration of the tasks
(20)
performed in the working shifts throughout the year . This requires occupational hygiene expertise,
and the information most often includes:
— the job classification of the company;
— the inventory of tasks within a job;
— the task specific exposure profile;
— the operational conditions and risk management measures;
— the duration and location of the exposure within the shift and throughout time, determined by the
frequency and period of the tasks;
— experience of the workforce;
— etc.
The SEG concept is developed to simplify the exposure assessment if several workers have the same
exposure profile. If the exposure profile is specific to only one worker then the worker's exposure is
assessed in the same manner as in the SEG.
If a SEG includes workers from different locations, care shall be taken that the SEG meets the definition
3.1.3 of this European Standard.
5.2.2 Specifying the measuring procedure
The aim of the measuring procedure and sampling strategy is to obtain valid and representative
measurements of the exposure of the workers for comparison with the OELVs taking into account all
possible conditions which can reasonably expected to be present throughout time.
Measuring procedures shall comply with the requirements of EN 482. If this is not technically feasible,
the reasons shall be given in the report.
NOTE EN 482 refers to further requirements (e.g. on sensitivity, limit of quantification, specificity, capacity of
samplers, transportation, stability) in other European Standards such as EN 481, EN 838, EN 1076, EN 13205-1,
EN 13890 and EN 13936.
In order to measure the exposure of the worker at the workplace, personal sampling devices shall be
used whenever possible, attached to workers' clothing within the breathing zone; workers should be
informed about the purpose of the measurement and special recommendations about behaviour during
the sampling time. Due to spatial variability of the concentration of chemical agents in workplace
atmospheres, static sampling is generally less representative of worker exposure.
The sampling duration is also an important factor that can influence the representativeness of exposure
measurements. The sampling duration may exceed the OELV reference period if it is necessary to obtain
valid and representative measurements in case of extended workshifts (>8 h).
The sampling duration should be chosen to represent the exposure for the task/activity and
representatively describe the exposure for the reference period which is assessed (see Annex D). For
this purpose the performance characteristics of the measuring procedure shall be taken into
consideration.
The sampling duration should be as close to the OELV reference period as it is necessary to determine
the average exposure for the reference period. If the total sampling duration is less than the OELV
reference period, then the unsampled time should be assessed carefully and critically for exposure
changes that have occurred in the unsampled period and that cannot be ignored. Examples of such
situations are presented in Annex D.
For testing compliance with OELV-8 h, three cases shall be considered:
— If exposures occur throughout the workshift and the appraiser considers that the workplace
factors, including the tasks, are constant during the workshift, the total sampling duration may be
shorter than the reference period with a minimum of 2 h;
— If the appraiser considers that the workplace factors, including the tasks, are not constant during
the workshift, the total sampling duration shall be longer than 2 h and as close as possible to the
shift duration;
— If the duration of exposure within the workshift is less than 2 h, the sampling duration should cover
the whole period of exposure.
When testing compliance with short-term OELV, the sampling duration shall be 15 min.
Measurements shall be performed on sufficient days and during various specific operations in order to
gain insight into the pattern of exposure. It is important to consider different episodes during which
exposure conditions can vary (night and day cycles, seasonal variations).
The minimum number of measurements shall be in accordance with 5.5.2 and 5.5.3. The appraiser shall
also take into consideration the number of workers belonging to the SEG in order to determine the
number of measurements that shall be conducted, to ensure that the results are representative of the
whole SEG. This is especially important if workers in a SEG belong to different locations.
The workers chosen for exposure measurement, and the times of measurement, shall be selected so that
the measured exposures are representative of the exposure of the workers in the SEG, and this means
that it can be necessary to make the measurements at different times. If the number of measurements to
be made is greater than the number of workers in the SEG, it will be necessary to measure some
workers more than once. As far as possible, this shall be done to make the measurements
representative of the exposures in the SEG.
5.3 Performing exposure measurements
Before starting the survey, the appraiser shall make contact with the employer and should ensure that
workers are informed about the objectives of exposure measurements. The appraiser shall check that
the work activity is consistent with that taken into account in the sampling strategy. The appraiser shall
monitor the success of the sampling operation by remaining on site or arranging for it to be done by
another person who is sufficiently trained and experienced to monitor the operation effectively. For
each sample, the appraiser shall document the following relevant information for the future
[18]
:
interpretation of the results of exposure measurements
— identification of the SEG and of the workers;
— description of the workplace;
— chemical agents relevant for the activity;
— work tasks performed;
— daily working hours and the duration of exposure to chemical agents considered;
— RMM such as engineering control (including their operational status), PPE, work organization, etc.;
— relevant environmental conditions at the workplace (for example temperature, relative humidity,
atmospheric pressure, air movement);
— interferences by nearby work activities or others (e.g. smoking);
— presence of other or unusual activities, incidents, etc.;
— sampling information, such as identification of samples and technical sampling equipment used,
sampling flow rate, start and end of sampling, etc.
5.4 Validation of results and SEGs
5.4.1 General
Before testing compliance with the OELV it is necessary to consider the validity of each measurement
and to use the measurements to evaluate the constitution of the SEG for testing compliance as explained
in 5.5.
5.4.2 Validation of measurement results
When the measurement results are available, each measurement shall be evaluated using the
information collected during measurement, and by comparison with the other measurements of the
SEG.
If the result is unusually high or low, the possibility that this is because of errors of sampling or analysis
shall be considered, and if this is the case then the result shall be excluded. However, before excluding a
measurement, appraiser notes, and/or contextual information shall be used to identify measurements
for which accidents with equipment or malfunctions, or deliberate misuse have occurred in relation to
the activity, sampling or analysis. If no such irregularity can be reliably identified, the measurement
shall not be excluded. If measurements are excluded, it may be necessary to repeat measurements to
have sufficient representative measurements to compare with the OELV.
Any removal of results and the reasons shall be explicitly described in the report.
5.4.3 Validation of SEGs
After results have been accepted, they shall be used to validate the constitution of each SEG. Based on
expert judgement and information collected during the measurements and the basic characterization,
the appraiser shall be able to confirm the constitution of SEGs. When the number of valid
measurements is at least 6, the distribution of results shall be examined.
Exposure measurements are usually log normally distributed. To check whether all individuals belong
to the same SEG, and whether the distribution of measurements is log-normal, the log probability plot
of the data shall be analysed. Guidance is given in Annex E.
An important complication is that two workers doing the same job may not have the same exposure.
This phenomenon, known as between-worker variability, means that measurements of one worker’s
exposure cannot simply be assumed to apply to others doing nominally the same job. Furthermore,
exposure varies from shift to shift, giving rise to within-worker variability.
If the measurements show that one or more workers have exceptional exposure, which seems
inconsistent with the distribution of results from the rest of the SEG, the reasons shall be investigated
and these workers may be treated separately, for example forming a new SEG and taking more
measurements as necessary. Guidance is given in Annex E. It may be necessary to repeat exposure
measurements to have sufficient representative measurements for each SEG to test compliance.
Any changes to the SEG as a result of these tests shall be recorded in the report (see Clause 6).
5.5 Comparison of results with OELVs
5.5.1 General
5.5.2 and 5.5.3 describe the comparison with an OELV for a single chemical agent. In case of activities
[33]
involving exposure to several hazardous chemical agents, the EU directive 98/24 specifies that the
risk shall be assessed on the basis of the risk presented by all such chemical agents in combination. For
these situations an exposure index can be calculated from the exposures and the OELVs as described in
Annex C. The value of the index shall be compared with 1 instead of comparing the exposure with the
OELV. The exposure index is the sum of the exposure of each chemical agent present divided by its
OELV:
n
E
i
I=  (1)
∑
OELV
i=1
i
where
is the exposure to chemical agent i.
E
i
The appraiser shall choose between different approaches mentioned in Annex C.
In the case of extended work shift, the daily exposure (E ) is used for comparison with the OELV (see
d
Annex G).
This European Standard does not take into account the use and effectiveness of RPE in testing
compliance with the OELV.
5.5.2 Preliminary test
The preliminary test requires three to five valid exposure measurements (see 5.4) on workers
belonging to a SEG.
a) If all results are below:
1) 0,1 OELV for a set of three exposure measurements, or
2) 0,15 OELV for a set of four exposure measurements, or
3) 0,2 OELV for a set of five exposure measurements,
then it is considered that the OELV is not exceeded: Compliance.
b) If one of the results is greater than the OELV, it is considered that the OELV is exceeded: Non-
compliance.
c) If all the results are below the OELV and one result is above 0,1 OELV (set of three results) or 0,15
OELV (set of four results) or 0,2 OELV (set of five results) it is not possible to conclude on
compliance with the OELV. No-decision. In this situation additional exposure measurements shall
be carried out (requiring at least at total of six measurements) in order to apply the test based on
the calculation of the confidence interval of the probability of exceeding the OELV, as specified in
5.5.3.
According to EN 482, the measuring range for short-term exposure measurements may be from 0,5 to 2
times the OELV. In this case, the preliminary test cannot be used for short-term measurements
(reference period equal to 15 min).
5.5.3 Statistical test
The appraiser shall select a statistical test to check whether the exposures of the SEG comply with the
OELV. The test shall measure, with at least 70 % confidence, whether less than 5 % of exposures in the
SEG exceed the OELV.
A suitable test is given in Annex F. Other tests may be used provided that they have been shown to meet
the above confidence specification.
The appraiser shall make exposure measurements of the SEG according to the procedures in 5.2.2 and
5.3, in a way which meets the requirements of the test chosen. The results shall be analysed statistically
according to that test.
If one or more of the exposure measurements are below the limit of quantification (LOQ), and the
statistical test selected involves use of geometric (GSD) or standard (SD) deviations and/or geometric
(GM) or arithmetic (AM) means, then the values below the LOQ shall be treated in a way which
produces a reliable result. Methods are described in Annex H for a case where a minority of results
are < LOQ.
Applying such tests to the exposure measurements assumes that the measurements are log-normally
distributed (see Annex E). This is usually true at least approximately, and it is unusual to have enough
measurements to show statistically that it is not true.
6 Report
Reports shall be written of the occupational exposure assessment and of any periodic measurement.
The report shall contain the following information:
— name of the appraiser and institutions undertaking the assessment and the measurements;
— purpose of the assessment;
— name of the chemical agents considered;
— name and address of premises;
— description of the workplace factors and working conditions;
— observations made during sampling;
— results and conclusions of the basic characterization;
— measuring procedure and equipment used and agreement with requirements of EN 482 (see Note
in 5.2.2);
— time schedule (date, beginning and end of sampling);
— exposure concentrations;
— details of quality assurance (e.g. expanded uncertainty according to EN 482);
— clear identification of results;
— result of the comparison with the limit value.
If RPE is used, the results of measurements do not correspond to the concentration inhaled by the
workers and this shall be reported.
In case of non-compliance, the apprai
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