🌿 Chromium and its compounds in workplace air — FAAS, PN-Z-04434

Environment PN-Z-04434

Overview

WHAT THIS STANDARD DESCRIBES. The scope from the PKN catalogue card reads: "Metoda polega na zatrzymaniu chromu i jego związków na filtrze membranowym, mineralizacji próbki w stężonym kwasie azotowym(V), sporządzeniu roztworu do analizy w rozcieńczonym kwasie azotowym(V). Chrom i jego związki w roztworze oznacza się metodą płomieniową absorpcyjnej spektrometrii atomowej. Najmniejsze stężenie chromu i jego związków, jakie można oznaczyć tą metodą wynosi 0,035 mg/m3" [The method consists in retaining chromium and its compounds on a membrane filter, digesting the sample in concentrated nitric(V) acid and preparing the test solution in dilute nitric(V) acid. Chromium and its compounds in the solution are determined by flame atomic absorption spectrometry. The lowest concentration of chromium and its compounds that can be determined by this method is 0.035 mg/m3]. The standard was published on 12 September 2011 in a Polish-language version, has seven pages and is maintained by KT 159 Chemical and Dust Hazards in the Working Environment. It replaced PN-Z-04126-01:1979. The card has neither a "Withdrawn" header nor a "Withdrawal date" row (checked on 23.09.2026).

TWO LIMIT VALUES DIFFERING A HUNDREDFOLD — AND THE RESULT OF THE DETERMINATION DOES NOT SETTLE WHICH ONE APPLIES. The list of maximum admissible concentrations, in the wording given by the regulation of 26 March 2026 (Journal of Laws 2026 item 447), carries chromium under TWO separate items: **item 120 "Chrom metaliczny" [metallic chromium] — NDS 0.5 mg/m³**, without a short-term value, and **item 582 "Związki chromu(VI) – w przeliczeniu na Cr(VI)" [chromium(VI) compounds — as Cr(VI)] — NDS 0.005 mg/m³**, also without a short-term value. The difference is a hundredfold.

SUPPLEMENT (23.09.2026): THERE ARE TWO ITEMS, BUT FOUR SUBSTANCE NAMES — AND THIS MATTERS MORE TO THE READER OF A REPORT. Item 120 does not cover metallic chromium alone: under the same number, with the same value of 0.5 mg/m³ and the same CAS number [7440-47-3], the list also carries **"Związki chromu(II) – w przeliczeniu na Cr(II)" [chromium(II) compounds — as Cr(II)]** and **"Związki chromu(III) – w przeliczeniu na Cr(III)" [chromium(III) compounds — as Cr(III)]** (reading of the text of the act on 23.09.2026, string: "120 Chrom metaliczny 0,5 – – – – – – – [7440-47-3] Związki chromu(II) – w przeliczeniu na Cr(II) Związki chromu(III) – w przeliczeniu na Cr(III) 121 Cisplatyna" [metallic chromium; chromium(II) compounds — as Cr(II); chromium(III) compounds — as Cr(III); cisplatin]). The next numbered item is 121, cisplatin, so the first three names share one row of the list. FOR THE ASSESSMENT OF EXPOSURE THIS MEANS SOMETHING CONCRETE, NOT MERELY A MATTER OF ORDER: chromium in oxidation states II and III HAS NO separate, stricter value of its own — it shares the threshold of 0.5 mg/m³ with metallic chromium. The result of a determination of total chromium may therefore be compared with 0.5 mg/m³ for this whole trio at once, and the only form that breaks ranks is chromium(VI) from item 582. The decision "permitted or not permitted" thus depends on ONE question — whether Cr(VI) occurs at the workplace — and not on distinguishing all the oxidation states. WHAT IS CONFIRMED IN THIS READING: the values 0.5 and 0.005 themselves. In some text extractions of the act the item numbers lie in a different block from the names and values, and then assigning a number to a row would be guesswork; in the reading used here the number stands directly after the substance name — "Chrom metaliczny 0,5" [metallic chromium] and "582 Związki chromu(VI) – w przeliczeniu na Cr(VI) 0,005" [chromium(VI) compounds — as Cr(VI)] — and that is why both values remain in this entry as checked, not assumed. Meanwhile, the method of this standard determines TOTAL CHROMIUM: digestion in nitric(V) acid brings all forms of chromium into solution, and flame atomic absorption spectrometry measures the element, not the oxidation state. A result of "0.2 mg/m³ of chromium" is therefore at the same time two and a half times LOWER than the value for metallic chromium and forty times HIGHER than the value for chromium(VI) compounds — and without knowing the composition of the aerosol at the workplace it is impossible to say whether the conditions are met.

WHAT THIS MEANS FOR THE REPORT. The result of this determination may be compared with the value of 0.5 mg/m³ only when it is known that no chromium(VI) compounds occur at the workplace — and this is knowledge about the process, not about the sample: electroplating with chromium, welding stainless steels and plasma cutting produce Cr(VI), whereas machining metallic chromium does not. If the presence of Cr(VI) cannot be ruled out, a SPECIATION determination is needed, which this standard does not describe. A laboratory that has only PN-Z-04434 in its scope should say so in the report — otherwise the recipient will take a number compared with the wrong threshold for an assessment of exposure.

THE LOWEST DETERMINABLE CONCENTRATION AGAINST BOTH THRESHOLDS. The card gives 0.035 mg/m³. Against the value for metallic chromium (0.5 mg/m³) this is **one fourteenth** — i.e. the method meets the requirement of PN-EN 482 that quantification should reach one tenth of the limit value. Against the value for chromium(VI) compounds (0.005 mg/m³) it is **SEVEN TIMES the threshold** — the method cannot demonstrate compliance with this value, because it does not even get down to its level. The same limit-of-quantification figure is thus once sufficient and once useless, depending on which item of the list applies at the workplace.

SCALE OF CITATIONS (reading of 23.09.2026, copy of the database of accreditation scopes). Matching by the BEGINNING of the notation, i.e. the way the "Laboratories" tab searches: 25 entries at 21 laboratories. Across all forms of the core "04434": the same — 25 / 21, because no laboratory writes this standard in a distorted form. Six different forms of notation, and the balance closes down to the single occurrence: "PN-Z-04434:2011" 20 times, "PN-Z-04434" without a date 1, and four notations with an addition — a clause number ("pkt 6", "pkt.6 i pkt.10" [pkt = clause]) or the number of the laboratory's own test procedure ("Wyd. 1 z dnia 25.05.2022 r." [Wyd. = issue, z dnia = dated]). The ratio of entries to laboratories is 1.2, i.e. the standard is dispersed: practically every laboratory has it in a single row of its scope.

TWO NOTATIONS WITH A CLAUSE NUMBER SAY MORE THAN THEY SEEM TO. A laboratory that enters "PN-Z-04434:2011 pkt 6" in its scope declares that it performs only part of the procedure — clause 6 of this standard is sampling. The scope with the addition "pkt.6 i pkt.10" covers sampling and the calculation of the result. A reader of the scope looking for a laboratory that performs the WHOLE determination must read these additions, because in the "Laboratories" tab all three entries look the same.

SIX FORMS OF NOTATION AND NOT ONE DISTORTED — BUT ONE MISLEADS WITH ITS YEAR (23.09.2026). In accreditation scopes this standard occurs in six forms: "PN-Z-04434:2011" (20 entries at 18 laboratories), "PN-Z-04434" without a year, "…:2011 pkt.6 i pkt.10", "…:2011 pkt 6", "…:2011 z wył. pkt. 6 i pkt.10" [z wył. = excluding] and "PN-Z-04434:2011 Wyd. 1 z dnia 25.05.2022 r." — one entry each. The balance agrees: 24 occurrences for 24 entries, so no value is repeated or truncated, which is rare with this many forms. THE LAST FORM NEEDS A SENTENCE, HOWEVER, BECAUSE A READER OF THE TAB WILL TAKE IT FOR A NEWER EDITION OF THE STANDARD: "Wyd. 1 z dnia 25.05.2022 r." DOES NOT CONCERN THE STANDARD, but the laboratory's TEST PROCEDURE. The standard dates from 12 September 2011 and there is no newer edition; the year 2022 is the date of approval of the internal document that implements this standard. THIS IS NOT A PECULIARITY OF THIS ONE NOTATION: in the whole set, 542 entries at 119 laboratories have a calendar date in the reference-document field, 537 at 122 the phrase "z dnia" [dated], and 339 at 85 the word "wydanie" or "Wyd." [issue] — in each of these cases the designation of the laboratory's procedure stands next to the designation of the standard ("PN-T-06580-3:2002 … IMB edycja 4 z dnia 05.06.2025 r.", "PN-EN 14385:2025-05 WBJ-2/IB/183 wydanie 5 z dnia 12.06.2025 r."). There are two consequences: the year of the procedure is sometimes newer than the year of the standard and looks like its edition, and the notation itself is unique by definition, because the procedure number is the laboratory's own.

Method principle

The aerosol containing chromium and its compounds is retained on a membrane filter while a known volume of air is drawn through it. The filter is digested in concentrated nitric(V) acid, and the resulting residue is dissolved in dilute nitric(V) acid. The solution is introduced into the flame (acetylene–air or acetylene–nitrous oxide, depending on the laboratory's procedure) and the absorbance is measured at the chromium resonance line of 357.9 nm. The concentration in air is calculated from the mass of chromium in the solution, the volume of the solution and the volume of air drawn. The method measures TOTAL chromium — digestion removes the difference between metallic chromium, chromium(III) and chromium(VI).

Applications

• Periodic measurements of occupational exposure required by the regulation of the Minister of Health on tests and measurements of agents harmful to health in the working environment
• Electroplating shops, stainless-steel welding shops, grinding shops and plasma cutting — workplaces where chromium occurs in the aerosol
• Assessment of the effectiveness of local exhaust ventilation at chromium-plating workplaces
• Personal dosimetry in the worker's breathing zone, with sampling in accordance with PN-Z-04008-7

Key parameters

Standard

Standard number

PN-Z-04434:2011 (wersja polska)

Title (PL)

Ochrona czystości powietrza -- Oznaczanie chromu i jego związków na stanowiskach pracy metodą płomieniową absorpcyjnej spektrometrii atomowej

Title (EN)

Air purity protection — Determination of chromium and its compounds at workplaces by flame atomic absorption spectrometry

Step-by-step procedure

1. Sampling

   Draw a known volume of air from the worker's breathing zone through a membrane filter; choose the volume so that the expected concentration falls within the range of the method.

2. Digestion

   Digest the filter in concentrated nitric(V) acid.

3. Test solution

   Dissolve the residue in dilute nitric(V) acid and make up to a known volume.

4. Measurement

   Measure the absorbance of the solution by FAAS at the 357.9 nm line and read the concentration from the calibration curve.

5. Calculation

   Calculate the concentration of chromium in air from the mass in the solution, the volume of the solution and the volume of air drawn.

6. REFERENCE TO THE LIMIT VALUE — a step that requires knowledge from outside the measurement

   Establish whether chromium(VI) compounds may occur at the workplace. If NOT — compare with the NDS of 0.5 mg/m³ (item 120). If YES, or if this cannot be ruled out — the result is NOT suitable for assessing exposure, because the value for Cr(VI) is 0.005 mg/m³, i.e. seven times less than the limit of quantification of the method; a speciation determination is needed. Record the reservation in the report.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Concentrated nitric(V) acid — corrosive and oxidising; carry out the digestion in a fume hood, wearing chemically resistant gloves and safety goggles
• Chromium(VI) compounds are category 1 carcinogens — sampling at workplaces where they may occur is carried out wearing respiratory protective equipment
• Acetylene–air flame: work in accordance with the spectrometer's instructions and check the tightness of the gas installation

Frequently asked questions