🌿 Continuous measurement of nitrogen dioxide (NO2) and nitrogen monoxide (NO) concentrations in ambient air by chemiluminescence — NO reacts with excess ozone in the reaction chamber, the radiation of excited NO2 (600–3000 nm) is measured by a photomultiplier or photodiode; NO2 is calculated from the difference after the air has passed through an NO2→NO converter; analysers selected on the basis of type approval testing, suitability at the site assessed by calculating the expanded uncertainty (≤ 15 % for fixed measurements, ≤ 25 % for indicative), requirements for the sampling system (PTFE, FEP, glass, steel; losses < 2.0 %) and quality control; certification range NO2 up to 500 µg/m³, NO up to 1200 µg/m³; PN-EN 14211:2013-02 (withdrawn 29.05.2025, replaced by PN-EN 14211:2025-05)

Environment PN-EN 14211

Overview

WHAT THE STANDARD COVERS. We read the text of the standard in the iTeh sample of SIST EN 14211:2012 (Slovenian adoption of EN 14211:2012 of August 2012, English text) — PN-EN 14211:2013-02 adopts EN 14211:2012 as identical (PKN card): foreword, Clauses 1–5 and Clause 6 up to 6.3.1 — the sample ends on page 13. We do not read the rest of the sampling system (6.3–6.5), the analyser (7), type approval (8), field operation and quality control (9), expression of results (10), the report (11) or the annexes. We also read the beginning of the iTeh sample of SIST EN 14211:2025 (EN 14211:2024): the European foreword and Clause 1 — to compare the scope of the new edition.

ACCORDING TO THE TEXT OF EN 14211:2012. The standard was prepared by CEN/TC 264 “Air quality” (secretariat DIN); CEN approved it on 10.05.2012, national adoption by February 2013 at the latest; it supersedes EN 14211:2005, the changes are listed in Annex H. Scope (1): continuous method for determining NO2 and NO concentrations in ambient air based on chemiluminescence; performance characteristics and minimum criteria for selecting an analyser by type approval testing; evaluation of the suitability of an analyser at a given site for the data quality requirements of Annex I of Directive 2008/50/EC; requirements for sampling, calibration and quality assurance; NO2 up to 500 µg/m³, NO up to 1200 µg/m³ — these are the certification ranges in type approval; other ranges possible; for purposes other than the Directive the ranges and uncertainty requirements may not apply; rural, urban background, traffic and industrially influenced areas; results in µg/m³ at 20 °C and 101.3 kPa (500 µg/m³ NO2 = 261 nmol/mol, 1200 µg/m³ NO = 962 nmol/mol); Clauses 5–7 — principles and sampling, Clause 8 — for type approval test houses, Clauses 9–11 — for monitoring networks. References (2): e.g. EN 15267-1 and -2 (certification of automated measuring systems), EN ISO 6142, 6143, 6144, 6145-6, -7, -10 (calibration gas mixtures), EN ISO 14956, EN ISO/IEC 17025, ENV 13005. Definitions (3): e.g. adjustment (in this standard usually on the data, not the analyser), ambient air (outdoor air in the troposphere, excluding workplaces), availability of the analyser, calibration, certification range, check, converter efficiency (degree of conversion of NO2 to NO in %), detection limit (3.3 × standard deviation of response at zero / slope), expanded uncertainty (k = 2, approx. 95 %), independent measurement (at least four response times), individual measurement, lack of fit, lag and response time, limit value, short-term (12 h) and long-term drift, period of unattended operation, repeatability, reproducibility under field conditions (two analysers in parallel), residence times, type approval test (at least two analysers of the same pattern). Principle (5): characteristics are determined in a type approval test (laboratory and field); the choice of analyser for a task is based on the expanded uncertainty from the type approval results and site conditions; the expanded uncertainty of the method shall not exceed 15 % for fixed and 25 % for indicative measurements (Annex I of Directive 2008/50/EC); measurement: air through a filter (protecting the optics) at constant flow into the reaction chamber, NO with excess ozone; NO + O3 → NO2* + O2, NO2* → NO2 + hν; radiation 600–3000 nm with a maximum around 1200 nm, filtered and converted by a photomultiplier or photodiode; for NO2 the air passes through an NO2 → NO converter, signal = NO2 + NO, NO2 from the difference; concentrations are measured in volume/volume units and converted to µg/m³ with standard factors; the type approval test is performed by a designated body on at least two analysers in parallel; before installation the uncertainty is calculated from type approval values and station conditions to show compliance for all applicable limit values; after installation correct functioning is tested. Sampling (6.1–6.3.1): a single line or a common inlet with a manifold; losses of NO2 in the system and filter and formation of NO2 from the reaction of NO with ozone in the system and analyser affect the result but cannot currently be quantified — they are limited by minimum requirements, quality control and maintenance; the standard does not specify the location (guidance in Annex III of the Directive); inlet protected against rain, line as short as practical (residence time), particle filter before the analyser, with a manifold an additional pump; materials: PTFE, FEP, borosilicate glass or stainless steel; losses of NO and NO2 on the inlet and line materials < 2.0 %.

ACCORDING TO THE SAMPLE OF EN 14211:2024. CEN approved it on 11.11.2024, national adoption by June 2025 at the latest; it supersedes EN 14211:2012; the foreword refers the technical changes to Annex H, while the contents in the sample list “Annex I — Significant technical changes”. Scope (1) has the same content: NO2 up to 500 µg/m³ and NO up to 1200 µg/m³, the same types of area, result in µg/m³ at 20 °C and 101.3 kPa; “type approval” is replaced by “type testing”, and Note 2 points to example uncertainty budgets (Annexes F–H) and the possibility of using new limit values if the Directive changes.

STATUS (as of 03.10.2026). PKN card PN-EN 14211:2013-02 (English version): publication date 28.02.2013, withdrawal date 29.05.2025, introduces EN 14211:2012 [IDT], replaces PN-EN 14211:2005, “Replaced by PN-EN 14211:2025-05”. Card PN-EN 14211:2025-05 (English version): publication date 29.05.2025, introduces EN 14211:2024 [IDT], without a withdrawal note — end of the chain. What the withdrawal changes for the result: from the parts read, the certification ranges, reference conditions and areas of application remain the same; we have not read the list of technical changes (Annex H or I of the 2024 edition), so we do not state which type testing, quality control or uncertainty budget requirements have changed.

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 14211 appears in 2 records at 2 laboratories: AB 1057 and 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) the number appears at the same 2 laboratories — at AB 1057 in 9 items (the same item for successive monitoring stations), at AB 1622 in 1; in every document the number of page markers equals the number of PDF pages, without repetitions; a search of all PCA documents downloaded from BIP on 03.10.2026 found no laboratories outside the database copy. The form “PN-EN 14211:2013-02” at both — also in the AB 1057 document issued on 06.06.2025, a week after this edition was withdrawn. None of these items is suspended (the word “zawieszonego” in the AB 1622 document refers to suspended particulate matter). The “Laboratories” tab (query “PN-EN 14211”) shows both laboratories — checked by a tab query on the labcoda.pl production server on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). AB 1057: general environment — ambient air at monitoring network stations — NO (1.3–625) µg/m³, NO2 (1.9–500) µg/m³, NOx (1.9–955) µg/m³, chemiluminescence method. AB 1622: ambient air — NO (1–275) µg/m³, NO2 (1–420) µg/m³, NOx (1–420) µg/m³, chemiluminescence method.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. NO2: it is the difference of two measurements (with and without the converter), so it depends on the converter efficiency (3.9, 5.2). Sampling system: losses of NO2 in the line and filter and formation of NO2 from NO and ozone in the system change the result, and the standard states that they cannot currently be quantified — they are limited by the material (PTFE, FEP, glass, steel), a short line and maintenance (6.1, 6.3.1). Units: the analyser measures in volume/volume units, and the result is given in µg/m³ at 20 °C and 101.3 kPa — conversion at other conditions gives a different number (1, 5.2). Range: the certification ranges are NO2 up to 500 and NO up to 1200 µg/m³ (1); NOx up to 955 µg/m³ (AB 1057) is a sum expressed by conversion, whose definition is not in the part read. Uncertainty: the requirement ≤ 15 % (fixed) and ≤ 25 % (indicative) applies to measurements for the Directive — for other purposes it may not apply (1, 5.1). Edition: both items cite PN-EN 14211:2013-02, withdrawn on 29.05.2025.

WHAT WE DO NOT GIVE. We do not quote the requirements for the analyser, the type approval procedures and criteria, field quality control, calculation of the result and uncertainty or the list of changes in the 2024 edition — they lie outside the samples. We do not summarize Directive 2008/50/EC, EN 15267 or the gas mixture standards in this entry. We do not give limit values for NO2 in air.

Method principle

Ambient air is drawn at constant flow through a filter into the reaction chamber of the analyser, where nitrogen monoxide reacts with excess ozone; the excited NO2 formed emits radiation (600–3000 nm) whose intensity, measured by a photomultiplier or photodiode, is proportional to the NO concentration. In the second channel the air passes through a converter reducing NO2 to NO, so the signal corresponds to the sum of NO and NO2; the NO2 concentration is calculated from the difference. Results in volume/volume units are converted to µg/m³ at 20 °C and 101.3 kPa.

Applications

• Continuous measurement of NO2 and NO in ambient air at monitoring stations — rural, urban background, traffic, industrial areas (1)
• Selection of analysers by type approval testing and assessment of their suitability at the site (1, 5.3, 5.4)
• Measurements for Directive 2008/50/EC — expanded uncertainty ≤ 15 % (fixed) or ≤ 25 % (indicative) (5.1)
• Ambient air — NO, NO2, NOx — 2 accreditation scope records of 2 laboratories in PCA (10 items)

Key parameters

Standard

Standard number

PN-EN 14211:2013-02

Title (PL)

Powietrze atmosferyczne — Standardowa metoda pomiaru stężenia ditlenku azotu i tlenku azotu za pomocą chemiluminescencji

Title (EN)

Ambient air — Standard method for the measurement of the concentration of nitrogen dioxide and nitrogen monoxide by chemiluminescence

Step-by-step procedure

1. Choice of analyser

   Type-approved analyser; uncertainty calculation for site conditions (5.3, 5.4). PN-EN 14211:2013-02 — withdrawn 29.05.2025, replaced by PN-EN 14211:2025-05 (PKN).

2. Installation

   Sampling system of inert materials, short line, filter; functional test after installation (5.4, 6.3.1).

3. Continuous measurement

   NO channel and NO+NO2 channel through the converter; NO2 from the difference (5.2).

4. Quality control

   Calibrations, checks, maintenance (9 — outside the sample).

5. Result

   Conversion to µg/m³ at 20 °C and 101.3 kPa (1; Clause 10 outside the sample).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The part of the standard read contains no separate safety requirements; excess ozone is used in the reaction chamber of the analyser (5.2)

Frequently asked questions