🌿 Continuous measurement of the ozone concentration in ambient air by ultraviolet photometry — the air flows through an absorption cell irradiated at 253.7 nm by a stabilized low-pressure mercury lamp, and absorption is measured by a photodiode or photomultiplier (a system with a measuring and a reference cell, or one cell with alternating air and air after catalytic removal of ozone); type-approved analyser, certification range up to 500 µg/m³, sampling system of PTFE, FEP, borosilicate glass or stainless steel, PTFE particle filter; result in µg/m³ at 20 °C and 101.3 kPa, PN-EN 14625

Environment PN-EN 14625

Overview

WHAT THE STANDARD COVERS. We read the text of the standard in two iTeh samples. SIST EN 14625:2012 (English text of EN 14625:2012): title page, contents, foreword, Clauses 1–5 and Clause 6 up to 6.3.2 (particle filter) — up to page 13. SIST EN 14625:2025 (English text of EN 14625:2024): title page, contents, foreword, Clause 1, Clause 2 and Clause 3 up to definition 3.15 — up to page 12. The annex listing changes between editions (in EN 14625:2024 — Annex I “Significant changes”, p. 113) is in neither sample.

ACCORDING TO THE TEXT OF EN 14625:2012. The standard was approved by CEN on 10.05.2012; it supersedes EN 14625:2005 (technical changes in Annex H). Scope (1): a continuous method for measuring the ozone concentration in ambient air based on ultraviolet photometry; performance characteristics and minimum criteria for selecting an analyser by type approval; assessment of an analyser’s suitability at a particular station for the data quality requirements of Directive 2008/50/EC; requirements for sampling, calibration and quality assurance; concentrations up to 500 µg/m³; other ranges may be used at rural stations monitoring ecosystems; when used for purposes other than the directive, the ranges and uncertainty requirements may not apply; rural, urban and urban-background areas; results in µg/m³ at 20 °C and 101.3 kPa (500 µg/m³ corresponds to 250 nmol/mol). Principle (5): type approval comprises a laboratory and a field test of at least two analysers operating in parallel and is carried out by a designated body; an analyser for a specific task is selected by calculating the expanded uncertainty from the performance characteristics obtained in type approval and the conditions at the station; the expanded uncertainty of the method shall not exceed 15 % for fixed measurements and 30 % for indicative measurements (according to Directive 2008/50/EC); before installation at the station the expanded uncertainty is calculated for the conditions of that station, and after installation correct operation is checked. Measuring principle (5.2): air flows continuously through an optical absorption cell irradiated by monochromatic radiation centred at 253.7 nm from a stabilized low-pressure mercury lamp; the transmitted radiation is measured by a sensitive photodiode or photomultiplier; the absorption is a measure of the ozone concentration; two systems: the difference in absorption between a measuring and a reference cell (dual-cell), or one cell fed alternately with ozone-containing air and air after a catalytic converter decomposing ozone; most analysers measure the temperature and pressure in the cell and convert the result to reference conditions — without this compensation it has to be done manually; the concentration is measured in volumetric units (when calibrated with a volumetric standard), and results are given in µg/m³ using the conversion factors (Clause 10). Sampling (6): a separate line or a manifold shared with other analysers; losses in the sampling system, in the particle filter and reaction with nitric oxide in the system and analyser reduce the ozone concentration and affect uncertainty — these contributions cannot currently be estimated, so they are not included in the uncertainty assessment but are limited by minimum requirements, quality control and maintenance; the standard does not specify the location of the sampling point (guidance in Annex III of Directive 2008/50/EC). Sampling system (6.3): inlet protected from rain, line or manifold as short as possible, of PTFE, FEP, borosilicate glass or stainless steel — influence of the material on the measured concentration through ozone losses < 2.0 %, influence of the pressure drop across the inlet, line and filter ≤ 1.0 %; moderate heating against condensation is permitted; PTFE particle filter in a housing inert to ozone, between the line and the analyser (may be built into the analyser; 5 µm is usually sufficient).

ACCORDING TO THE TEXT OF EN 14625:2024. The standard was prepared by CEN/TC 264 “Air quality” and approved by CEN on 11.11.2024; it supersedes EN 14625:2012, and the technical changes are listed in Annex I; national standards were to adopt it, and conflicting ones to be withdrawn, at the latest by June 2025. The scope (1) in the part we read has the same basic elements as in 2012: continuous method, type approval, assessment of the analyser’s suitability at the station (with reference to Annex I of Directive 2008/50/EC), up to 500 µg/m³ (certification range in type approval), results in µg/m³ at 20 °C and 101.3 kPa; the document describes itself as a development of the editions EN 14625:2005 and EN 14625:2012. New in the scope: an indication of which clauses are for whom — Clauses 5–7 and Annexes B–C generally on the principle and sampling, Clause 8 and Annex E for bodies testing analysers, Clauses 9–11 and Annexes F–G for monitoring networks; Note 4: analysers type-approved before publication of this edition may continue to be used for regulatory monitoring, and as analysers tested according to the new edition become available, older reference analysers should be phased out. The contents of EN 14625:2024 include the field uncertainty calculation at the level of the hourly alert threshold (Annex F) and the 8-hour target value (Annex G); the detection limit in definition 3.12: 3.3 · sr,z / B (standard deviation at zero concentration divided by the slope of the calibration function). References (2): EN 15267-1 and -2 (certification of air monitoring equipment), EN ISO 6145-6 and -7 (preparation of calibration gases by dynamic methods), EN ISO 14956 (evaluation of the suitability of a procedure by comparison with a required uncertainty), ISO 19229 (purity analysis of gases).

STATUS (as of 03.10.2026). In the PKN search (query “14625”, 03.10.2026) PN-EN 14625:2025-05 (English version, “Wprowadza: EN 14625:2024 [IDT]”) carries no withdrawal note; PN-EN 14625:2013-02 (English version) — “Wycofana i zastąpiona przez PN-EN 14625:2025-05 – wersja angielska”; PN-EN 14625:2005 — withdrawn and replaced by PN-EN 14625:2013-02. Card of PN-EN 14625:2013-02: publication date 28.02.2013, withdrawal date 30.05.2025, 96 pages, KT 280 Jakości Powietrza, introduces EN 14625:2012, “Zastąpiona przez PN-EN 14625:2025-05 – wersja angielska”. Card of PN-EN 14625:2025-05: publication date 30.05.2025, 116 pages, KT 280, ICS 13.040.20, “Zastępuje PN-EN 14625:2013-02 – wersja angielska”, no withdrawal note. What replaced it and what changed for the result: the scope, principle and reference conditions of the result are the same in the parts of both editions we read; we have not read the list of changes (Annex I of EN 14625:2024); according to Note 4 to Clause 1 of the new edition, analysers tested according to earlier editions may continue to be used for regulatory monitoring.

LEGISLATION (read 03.10.2026, texts from CELLAR). Directive 2008/50/EC in the consolidated text of 18.09.2015, Annex VI point A.8: the reference method for the measurement of ozone is described in EN 14625:2012 “Ambient air — Standard method for the measurement of the concentration of ozone by ultraviolet photometry”. Directive (EU) 2024/2881 of 23.10.2024 (recast), Annex VI point A.11: the reference method for measuring ozone in air corresponds to the method described in EN 14625:2012; its Article 31 repeals Directives 2004/107/EC and 2008/50/EC with effect from 12.12.2026, and Member States are to transpose Annexes I–X by 11.12.2026 (Article 30). Both acts therefore name the 2012 edition, which PN-EN 14625:2013 introduces — the withdrawal of the standard in PKN has not changed the reference method in legislation.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 03.10.2026). The number 14625 appears in 3 records at 3 laboratories: AB 337, AB 1057, AB 1622. In the current PCA documents (read 03.10.2026; AB 1622 issue no. 10 of 02.09.2024, AB 1057 issue no. 17 of 06.06.2025, AB 337 issue no. 20 of 15.07.2025) the number appears in 6 lines at the same 3 laboratories (at AB 1057 the number occurs four times in the document); in each document the number of page markers equals the number of PDF pages, without repetitions; a search of all PCA documents downloaded from the BIP on 03.10.2026 found no laboratories outside the database copy. The form is “PN-EN 14625:2013-02” (AB 1057, AB 1622) and “PN-EN 14625:2013” (AB 337) — all cite the edition withdrawn in PKN. None of these items is suspended (in the AB 1622 document the word “zawieszony” refers to “suspended particulate matter”). The “Laboratories” tab (query “PN-EN 14625”) shows all 3 laboratories — checked by a tab query on the labcoda.pl production server on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). Object: ambient air (AB 1622), general environment — ambient air (AB 337, AB 1057). Characteristic: ozone concentration. Ranges: (2.0–500) µg/m³ (AB 1057), (1–800) µg/m³ (AB 1622), (1.0–1000) µg/m³ (AB 337). Technique: ultraviolet photometry method (AB 1057, AB 1622), UV photometric method (AB 337).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Status: PN-EN 14625:2013 has been withdrawn in PKN since 30.05.2025, but Directives 2008/50/EC and (EU) 2024/2881 still name EN 14625:2012 — citing the withdrawn edition is here consistent with legislation, and the newer edition does not change the method in the part we read. Range: the certification and application range of the standard is up to 500 µg/m³ (1) — AB 1622 gives up to 800 and AB 337 up to 1000 µg/m³; the standard allows other ranges only at rural stations monitoring ecosystems, and outside the purposes of the directive its uncertainty requirements may not apply. Reference conditions: result in µg/m³ at 20 °C and 101.3 kPa; an analyser without automatic temperature and pressure compensation requires manual conversion (5.2). Sampling: ozone losses in the line, filter and reaction with nitric oxide lower the result and are not included in the uncertainty (6.1) — hence the requirements: PTFE, FEP, borosilicate glass or stainless steel (< 2.0 % influence), pressure drop ≤ 1.0 %, PTFE filter (6.3). Analyser: suitability is decided by the expanded uncertainty calculated for the given station from the type approval results — up to 15 % for fixed measurements and 30 % for indicative ones (5.1).

WHAT WE DO NOT GIVE. The type approval requirements, performance criteria, frequency of calibrations and checks, uncertainty calculations (Clauses 7–11, Annexes A–I) and the list of changes between editions are not quoted — they lie outside the samples. We have not checked the Polish regulation on the assessment of substance levels in air. We do not give ozone threshold values from legislation.

Method principle

Ambient air flows continuously through an absorption cell irradiated at 253.7 nm by a stabilized low-pressure mercury lamp; a photodiode or photomultiplier measures the transmitted radiation, and the absorption by ozone is a measure of its concentration. The absorption is determined as the difference between a measuring and a reference cell, or in a single cell fed alternately with air and with air from which ozone has been removed in a catalytic converter. The analyser converts the result, using measured temperature and pressure, to 20 °C and 101.3 kPa, in µg/m³.

Applications

• Continuous measurement of ozone in ambient air in rural, urban and urban-background areas, up to 500 µg/m³ (1)
• Reference method for measuring ozone according to Annex VI of Directive 2008/50/EC and Directive (EU) 2024/2881 (edition EN 14625:2012)
• Ambient air — items in the accreditation scopes of 3 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN 14625:2013-02

Title (PL)

Powietrze atmosferyczne — Standardowa metoda pomiaru stężenia ozonu z wykorzystaniem fotometrii w nadfiolecie

Title (EN)

Ambient air — Standard method for the measurement of the concentration of ozone by ultraviolet photometry

Step-by-step procedure

1. Analyser selection

   Type-approved analyser; expanded uncertainty for the station conditions ≤ 15 % (fixed) or 30 % (indicative) (5.1, 5.4). PN-EN 14625:2013-02 withdrawn in PKN on 30.05.2025; the directives name EN 14625:2012 (03.10.2026).

2. Sampling system

   Inlet, line or manifold of inert materials, PTFE filter; losses < 2.0 %, pressure drop ≤ 1.0 % (6.3).

3. Installation

   Check of correct operation after installation at the station (5.4).

4. Continuous measurement

   Absorption at 253.7 nm, temperature and pressure compensation (5.2).

5. Result

   µg/m³ at 20 °C and 101.3 kPa; quality control and maintenance according to Clause 9 (outside the samples) (1, 5.2).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Ozone is toxic — vent high-concentration calibration gases outdoors
• Mercury lamp — UV radiation and mercury; replace according to the manufacturer’s instructions

Frequently asked questions