🌿 Strategy for assessing inhalation exposure to chemical agents — basic characterisation, similar exposure groups (SEG), the sampling plan and testing compliance with limit values

Environment PN-EN 689

Overview

This is a standard about the measurement strategy, not about determining an agent. The scope reads plainly: „określono strategię wykonywania reprezentatywnych pomiarów narażenia inhalacyjnego na czynniki chemiczne w celu wykazania zgodności z wartościami dopuszczalnymi narażenia zawodowego (OELV)" [a strategy is specified for carrying out representative measurements of inhalation exposure to chemical agents in order to demonstrate compliance with occupational exposure limit values (OELV)]. It contains no reagents, no chromatographic columns and no calibration curves — the analytical course comes from separate substance standards, while PN-EN 689 says how many samples to take, from whom, for how long, when no measurement is needed at all, and how to derive from the set of results obtained a verdict on compliance. The standard sets one precondition for the determination method: "This European Standard is applicable for measuring procedures that fulfil the requirements of EN 482" — and if a procedure does not meet those requirements, part of the provisions of the strategy cannot be applied. The second limitation of the scope is hard: the standard does not apply to limit values with a reference period shorter than 15 minutes.

What "compliance" means — and why this is the heart of the matter. The introduction defines it in a single sentence: compliance means that the time-weighted average exposure of the worker is below the limit value with the corresponding reference period. A limit value never refers "to a measurement in general", only to a definite quantity, and confusing this changes the verdict. In the Polish system of limit values (the Regulation of the Minister of Family, Labour and Social Policy of 12 June 2018, Journal of Laws 2018 item 1286, § 2) there are three different references: NDS is the time-weighted average concentration for an 8-hour daily and average weekly working time; NDSCh is the average concentration over a period not longer than 15 minutes, occurring not more often than twice in a shift and at an interval not shorter than an hour; NDSP is a value which must not be exceeded at any moment — CIOP-PIB notes that no reference period is set for NDSP and that results are interpreted from samples whose sampling time in principle does not exceed 15 minutes. To NDS and NDSCh the strategy of PN-EN 689 applies directly; with NDSP one has to decide separately how to reconcile the absence of a reference period with the exclusion from the scope of the standard cited above. In calculating the time-weighted average concentration for 8 hours the denominator is always 8 hours, and not the sum of the sampling times — which is why a shift longer or shorter than 8 hours does not change the reference, it changes only the arithmetic.

Edition and corrigendum. The current edition is PN-EN 689+AC:2019-06, published on 26 June 2019, 57 pages, KT 159 for Chemical and Dust Hazards in the Working Environment; it implements EN 689:2018+AC:2019 [IDT] and supersedes PN-EN 689:2018-07. The catalogue card has neither a "Date of withdrawal" nor a "Superseded by" field, so the edition is in force. The AC corrigendum is not here a piece of metadata to be passed over: the European text incorporated Corrigendum 1 issued by CEN on 10 April 2019, and the foreword lists what it changed — the list of abbreviations, the content in several annexes and the bibliography and the references in the text; the places changed by the corrigendum are marked in the standard with start and end markers. That is why we conduct the description solely on the text with the corrigendum, and not on the 2018 edition. Both language versions were checked in the PKN catalogue, in accordance with the rule about corrigenda hanging on only one of them: the Polish version of this edition does not exist in the catalogue (the address of the card returns 404), the standard is available in the English version — and that is how CIOP-PIB cites it too.

What this description does not contain. The preview of the standard covers the pages up to and including clause 5.4.2 (13 out of the 53 pages of the preview pagination; the PKN catalogue card gives 57 pages — these are two different countings of the same document, not a contradiction). Clause 5.5 "Comparison of results with OELVs" — and hence the thresholds of the preliminary test (5.5.2) and the formula of the statistical test (5.5.3) — as well as clauses 6 "Report" and 7 "Periodic reassessment", and likewise the content of Annexes A–I, we have not seen and do not reproduce here. From the table of contents it is known only what these parts are called; the only piece of information we give from there is the title of Annex F.2: "SEG compliance test for at least six exposure measurements". A laboratory planning an assessment must obtain the full text of the standard; without clause 5.5 the verdict on compliance cannot be closed.

Place in the Polish system of tests and measurements. The obligation to measure the concentrations of chemical agents and dusts for which NDS values have been set follows from the Labour Code and from the Regulation of the Minister of Health of 2 February 2011 on tests and measurements of agents harmful to health in the working environment — in the wording of the CONSOLIDATED TEXT promulgated by the announcement of the Minister of Health of 3 July 2025 (Journal of Laws 2025 item 949). CORRECTION OF 11.09.2026: earlier editions of this entry cited Journal of Laws 2023 item 419 "as amended" — that is an OLDER consolidated text of the same regulation and today has in the ELI register the status "expiry of the act". An announcement with a consolidated text itself grows old: when further amendments come, the minister promulgates a new one and the previous one expires. The change is not a formal one — between one announcement and the other, § 6 and § 7 came to cover also REPROTOXIC SUBSTANCES alongside carcinogenic and mutagenic agents (amendment Journal of Laws 2024 item 1110, in force from 28-07-2024). The employer selects the substances for testing after identifying the sources of emission and the working conditions, consulting the workers on this. The rules for carrying out measurements and interpreting the results are linked by CIOP-PIB to two standards at once: PN-Z-04008-7:2002 together with Az1:2004 and PN-EN 689+AC:2019-06. In the practice of an occupational hygiene laboratory PN-EN 689 is the document which decides the value of all the measurement work: a well-performed analysis on a badly chosen sample says nothing about the worker’s exposure.

Method principle

Instead of measuring the exposure of every worker on every working day — which for chemical agents is unfeasible both in cost and technically — the strategy solves the problem of the variability of exposure by grouping and statistical inference. Workers with the same general exposure profile to a given agent (the same tasks, the same frequency of them, the same materials and processes, a similar way of carrying out the work) are combined into a similar exposure group (SEG). Measurements are made on a small number of persons from the group, and the result is referred to the whole group: if the measurements on part of the workers of the SEG indicate that the limit values are met, it is accepted that this applies to all the workers of that group. The standard itself warns that a single result — and even several results below the limit value — may not suffice for a reliable demonstration of compliance without the use of a statistical test such as the one proposed in the standard. The assessment is preceded by the basic characterisation: identification of the agents, a review of the workplace factors and an estimate of the exposure, on the basis of which a decision is taken whether measurements are needed at all. Respiratory protective equipment is not taken into account by the standard in testing compliance — it is the exposure that is assessed, not the dose inhaled by a worker in a mask.

Applications

• Assessment of occupational exposure to chemical agents and dusts as part of the tests and measurements required by the Regulation of the Minister of Health of 2 February 2011 — consolidated text Journal of Laws 2025 item 949 (position checked 11.09.2026)
• Planning a measurement campaign at a works: selecting the workplaces, forming similar exposure groups, establishing the number and duration of the samples
• Deciding whether measurements are necessary at all — the basic characterisation may show an exposure well below the limit value or, on the contrary, an exceedance of it straight away
• Interpreting the set of results from the laboratory: rejecting results affected by a sampling or analytical error, checking the correctness of the composition of the group, comparison with the limit value
• Periodic reassessment of the exposure and establishing the interval between successive measurements after changes in the process, the product or the list of limit values
• Agreeing the scope of the commission between the works and an accredited laboratory — what the result concerns (NDS or NDSCh) and what evidential material will be supplied

Key parameters

Standard

Standard number

PN-EN 689+AC:2019-06

Title (PL)

Narażenie na stanowiskach pracy — Pomiary narażenia inhalacyjnego na czynniki chemiczne — Strategia badania zgodności z wartościami dopuszczalnymi

Title (EN)

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

Step-by-step procedure

1. Naming the person conducting the assessment

   The assessment of occupational exposure on the basis of air samples is conducted by the "appraiser" — a person sufficiently trained and experienced in occupational hygiene, working techniques and measuring techniques, in respect of that part of the assessment which they carry out. They may be supported by a team of qualified persons.

2. Basic characterisation — identification of the agents

   Draw up a list of all the chemical agents present at the workplace: raw materials, primary products, impurities, intermediates, end products, products and by-products of the reaction and of the process; for each of them the registration numbers (CAS, EC), the hazardous properties, the classification and labelling, the applicable limit values, information on the significance of exposure through the skin and by the oral route (the standard concerns inhalation exposure only, but knowledge of the other routes is sometimes important), and also the quantity used, the vapour pressure, the temperature, the saturation concentration and the dustiness. The starting point is the safety data sheets.

3. Basic characterisation — review of the workplace factors

   Assess the processes and the ways of working: the organisation of work (activity, task, job title, shift system), the processes and techniques together with the temperature and pressure, the layout and configuration of the space (including confined spaces and work in the open air), the safety measures and procedures, cleanliness and order, the ventilation installations and other technical measures together with data on their effectiveness, the sources of emission and the places of high concentrations, the periods, frequencies and durations of exposure taking into account variability over the day and over the year, the workload, the behaviour of the workers and the indicators of production intensity.

4. Basic characterisation — estimate of the exposure and decision

   Collect data permitting a reliable estimate of the exposure: earlier results from that workplace (including from direct-reading instruments), results from comparable installations and processes, calculations and exposure modelling. The estimate leads to one of three decisions: exposure higher than the limit value — report this and recommend a programme for reducing the exposure by risk-management measures BEFORE compliance measurements; exposure well below the limit value — decide whether measurements are needed, and if not, report this and recommend a date for reassessment; information insufficient — pass to the sampling plan.

5. Forming similar exposure groups (SEG)

   Group the workers with the same general exposure profile to the agent examined. The basis is: the classification of jobs in the firm, the list of tasks within a job, the exposure profile proper to the task, the conditions under which the process is carried out and the risk-management measures, the duration and place of exposure within the shift and over a longer period (following from the frequency and the period of performance of the tasks), the experience of the workforce. If an exposure profile concerns only one worker, that worker’s exposure is assessed in the same way as a group. When workers from different locations are put into a group, check whether the group still meets the definition of a SEG.

6. Choosing the measuring procedure

   Choose a procedure meeting the requirements of PN-EN 482 (there one finds: unambiguity, selectivity, averaging time, measuring range and expanded uncertainty). PN-EN 482 refers further — to standards on sensitivity, limit of quantification, specificity, capacity of samplers, transport and stability of samples (among others EN 481, EN 838, EN 1076, EN 13205-1, EN 13890, EN 13936). If meeting the requirements of PN-EN 482 is not technically possible, give the reasons in the test report.

7. Establishing the manner and time of sampling

   Use personal samplers fixed to the clothing in the breathing zone, wherever possible; static sampling is as a rule less representative because of the spatial variability of concentrations. Inform the workers of the purpose of the measurement and of the recommendations for behaviour during sampling. Choose the sampling time to suit the reference period of the limit value: with an 8-hour value and constant conditions — not less than 2 h, with variable conditions — more than 2 h and as close as possible to the length of the shift, and when the exposure lasts less than 2 h — cover the whole of its period; with a short-term value the sampling time is 15 min. With working shifts longer than 8 h the sampling time may exceed the reference period — the standard permits this, and the result must then be referred to the proper period and not to the length of sampling. Assess the unsampled time critically with regard to changes in exposure which must not be passed over.

8. Distributing the measurements in time and within the group

   Carry out the measurements on a suitable number of days and during different operations, so as to learn the character of the exposure; take account of day–night cycles and of seasonal variability. Establish the number of measurements in accordance with clauses 5.5.2 and 5.5.3 of the standard and with the size of the group. Choose the workers and the dates so that the exposures measured are representative of the whole group; when there are to be more measurements than persons in the group, some workers are measured repeatedly.

9. Carrying out the measurements and documenting each sample

   Before beginning, contact the employer and ensure that the workers are informed of the purpose of the measurements; check whether the work being done corresponds to that assumed in the plan. Supervise the course of the sampling — personally or through another sufficiently trained person. For each sample record: the identification of the group and of the workers, a description of the workplace, the agents proper to the given activity, the tasks performed, the daily working time and the time of the exposure under consideration, the risk-management measures together with the state of their operation (ventilation, personal protective equipment, organisation of work), the environmental conditions (temperature, humidity, pressure, air movement), disturbances from neighbouring work and others (e.g. tobacco smoking), the presence of unusual activities and events, and the sampling data (identification of the samples and of the equipment, volume flow, beginning and end of sampling).

10. Validation of the results and of the composition of the groups

    Before testing compliance, assess the validity of each result and check whether the composition of the group is suitable for compliance testing. Assess each result on the basis of the information collected during the measurement and by comparison with the other results of the group. Consider an unusually high or unusually low result with regard to sampling or analytical errors and in such a case reject it — but before rejecting it consult the notes of the person conducting the assessment and the information on the circumstances of the measurement.

11. Comparison with the limit values and the test report

    The comparison with the limit value is carried out according to clause 5.5 of the standard: the preliminary test (5.5.2) and, when it does not decide, the statistical test (5.5.3), whereby Annex F.2 describes the group compliance test for at least six exposure measurements. The content of clause 5.5, of clause 6 (report) and of clause 7 (periodic reassessment) is not in the available preview of the standard — at this stage one has to work on the full text of PN-EN 689+AC:2019-06. In the test report note to which value the result was referred (NDS as a time-weighted average for 8 h, NDSCh as an average for 15 min) and that the assessment does not take into account the respiratory protective equipment used.

Required equipment and apparatus

Health and safety (OHS)

• The measurements are carried out in a working plant, at workplaces with real chemical exposure — the person taking the samples enters the same atmosphere as the one examined, and applies the protective measures provided for that workplace.
• In testing compliance the standard does not take into account the use or the effectiveness of respiratory protective equipment; a verdict of "compliant" is not a pronouncement on the safety of a worker in a mask, only on the level of exposure in the air.
• If the basic characterisation indicates that the exposure is probably higher than the limit value, it is recommended first to reduce it by risk-management measures and only then to plan compliance measurements — measurement does not take the place of action.
• Workers covered by personal dosimetry must be informed of the purpose of the measurement and of the recommendations for behaviour during sampling; the sampler on the clothing must not hinder the work or catch on parts of machines.
• The data collected with each sample (identification of the workers, tasks, events, tobacco smoking) concern particular persons — treat them as personal data and limit the circle of recipients of the report.
• Rejecting an unusual result without consulting the notes and the circumstances of the measurement is as dangerous as leaving it in: removing a real peak of exposure falsifies the assessment of the whole group.

Frequently asked questions