🌿 Calcium hydroxide in workplace air — inhalable and respirable aerosol fractions, flame atomic absorption spectrometry (FAAS); lowest determinable concentration 0.1 mg/m³ (inhalable, 720 l) and 0.07 mg/m³ (respirable); not used in the presence of other calcium compounds; MAC (NDS) 2 and 1 mg/m³; PN-Z-04497:2018-09

Environment PN-Z-04497

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card, in full (our translation): "This standard gives a method for determining calcium hydroxide (CAS No. 1305-62-0) in workplace air using flame atomic absorption spectrometry. The method is used in the control of sanitary and hygienic conditions. The method is not used in the presence of other calcium compounds in the air tested. The lowest concentration of calcium hydroxide that can be determined under the air sampling and determination conditions described in the standard is 0.1 mg/m3 in the inhalable aerosol fraction (for an air sample of 720 l) and 0.07 mg/m3 in the respirable aerosol fraction (for an air sample of 648 l)" (the card has a misspelling of "hydroxide" and no full stop). We did not have the text of the standard (10 pages).

ACCORDING TO THE CIOP PROCEDURE (J. Surgiewicz, "Calcium hydroxide. Determination in workplace air", Podstawy i Metody Oceny Środowiska Pracy 2019, no. 2(100), pp. 139–150 — read in full). The article describes a method developed at CIOP-PIB and recorded in the appendix as an analytical procedure; its scope coincides with the card of the standard, but the article does not say it is the text of the standard — the figures below are figures of the procedure in the article. Principle: a known volume of air is passed through membrane filters in fraction separators (inhalable and respirable; samples are taken simultaneously, sampler and separator next to each other), the filters are mineralised hot with concentrated nitric acid (hot plate, about 140 °C), solutions for analysis are prepared in dilute nitric acid with caesium chloride (0.2 % Cs) and lanthanum chloride (1 % La) as spectral buffers, and calcium is determined by F-AAS in an air–acetylene flame at 422.7 nm (stoichiometric flame, hollow cathode lamp). Cellulose ester filters with pores of 0.80 or 0.85 µm; up to 960 l of air through each filter at the flow rate recommended by the manufacturer of the sampler or separator — for the inhalable fraction most often 2 l/min; calcium calibration curve 0.50–20.00 µg/ml; result for each fraction separately: X = (C − Cs)·V1/(V·wm)·k·1.849, where 1.849 is the factor converting calcium to calcium hydroxide, k = 8 for the inhalable and 5 for the respirable fraction. Determination range: 0.10–4.11 mg/m³ in the inhalable fraction (720 l) and 0.07–2.70 mg/m³ in the respirable fraction (684 l); calcium LOQ 0.3 ng/ml, LOD 0.1 ng/ml; mean mineralisation efficiency 1.00 (requirement 1.00 ± 0.05); overall precision 5.45 %, expanded uncertainty 22.62 %; a several-fold excess of Al, Mg, Ba, Na does not affect the result, a 50–200-fold excess of other elements gives errors of a dozen or so per cent, and sulphuric and phosphoric acids considerably lower the calcium absorbance. The earlier method (Kołodyńska 1997) allowed a minimum of 0.5 mg/m³ to be determined and did not provide for separation into fractions.

NDS VALUES (list in the annex to the regulation of 26 March 2026, Journal of Laws 2026 item 447). Item 577: "Calcium hydroxide [1305-62-0]" — inhalable fraction: NDS 2 mg/m³, NDSCh 6 mg/m³; respirable fraction: NDS 1 mg/m³, NDSCh 4 mg/m³. The lowest determinable concentrations according to the card are 5 % of the NDS for the inhalable fraction and 7 % of the NDS for the respirable fraction.

STATUS (card as of 04.10.2026). The card of PN-Z-04497:2018-09 (Polish version) has no "Withdrawn" heading — the standard is CURRENT: published 12-09-2018, 10 pages, price group E, Health, Environment and Medicine Sector, KT 159 Chemical and Dust Hazards in the Working Environment, ICS 13.040.30; national standard, without the fields "Implements" and "Supersedes". The PKN search for "PN-Z-04497" (04.10.2026) returns only this standard.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data load up to 17.09.2026, read on 04.10.2026). The number 04497 appears in 8 records at 8 laboratories; in the current PCA documents (read on 03.10.2026; issues from 26.11.2025 to 23.07.2026) — in 8 rows at the same laboratories; a search of all PCA documents downloaded from the BIP found no laboratories outside the database copy; no item is suspended and no document repeats pages. All entries read "PN-Z-04497:2018-09"; AB 632 cites it next to instruction IB-13 edition 7 of 01.10.2023, and AB 719 cites "PN-Z-04497:2018-09 pkt 7" (clause 7) next to procedure PA-29 edition 18 of 30.01.2026 "excluding clause 3.6". The "Laboratories" tab (query "PN-Z-04497") shows all 8 laboratories — checked with the tab's query on the production server labcoda.pl on 04.10.2026.

WHAT THE LABORATORIES TEST (database copy). Object: working environment — air, air samples collected on filters. Quantity: concentration (content) of calcium hydroxide — inhalable and respirable fraction. Ranges in mg/m³: 0.012–12 (AB 849), 0.02–7.4 (AB 481), 0.03–12.00 (AB 1257), 0.03–32.5 for the inhalable and 0.03–23.3 for the respirable fraction (AB 882), 0.058–12.0 (AB 632), 0.06–12 (AB 647), 0.065–19.2 (AB 418); AB 719 — 0.00010–5.00 mg per sample for the inhalable and 0.00010–2.50 mg for the respirable fraction. Technique: flame atomic absorption spectrometry (FAAS) — 7 laboratories; AB 719 — inductively coupled plasma optical emission spectrometry (ICP-OES).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — other calcium compounds: according to the card the method is not used when other calcium compounds are present in the air tested, while what is determined is calcium, converted to the hydroxide (in the CIOP procedure with the factor 1.849); the card does not say how to check for the presence of other calcium compounds, and WE DO NOT GIVE this. Second — limit of quantification: according to the card the lowest determinable concentrations are 0.1 mg/m³ (inhalable) and 0.07 mg/m³ (respirable); all seven FAAS laboratories state a bottom limit lower than 0.07 mg/m³ (from 0.012 to 0.065 mg/m³) — this requires conditions different from those in the standard, which the report should name. Third — two fractions, two values: the NDS for the inhalable (2 mg/m³) and the respirable fraction (1 mg/m³) differ; the result is calculated separately for each fraction from a separate, simultaneously collected sample. Fourth — volume for the respirable fraction: the card gives 648 l, the CIOP article 684 l; the value 0.07 mg/m³ therefore cannot be assigned to one volume without the text of the standard. Fifth — technique: AB 719 determines calcium hydroxide by ICP-OES and cites only clause 7 of the standard.

WHAT WE DO NOT GIVE. We did not have the text of the standard — we give the figures of the procedure from the CIOP article and label them as such; we do not attribute them to the standard. We do not give the content of clause 7 cited by AB 719.

Method principle

Calcium hydroxide aerosol from workplace air is collected simultaneously on two membrane filters in inhalable and respirable fraction separators. The filters are mineralised hot with concentrated nitric acid, the solutions are prepared in dilute nitric acid with caesium and lanthanum buffers, and calcium is determined by flame atomic absorption spectrometry (in the CIOP procedure at 422.7 nm, air–acetylene flame); the result is converted to calcium hydroxide separately for each fraction and compared with the NDS of 2 mg/m³ (inhalable) and 1 mg/m³ (respirable). The method is not used when other calcium compounds are present in the air.

Applications

• Workplace air — calcium hydroxide, inhalable and respirable fraction — in the scopes of 8 laboratories
• Assessment of occupational exposure against the NDS of 2 and 1 mg/m³ and the NDSCh of 6 and 4 mg/m³ (Journal of Laws 2026 item 447, item 577 of the list)
• Calcium hydroxide dust without other calcium compounds in the air (PKN card)

Key parameters

Standard

Standard number

PN-Z-04497:2018-09

Title (PL)

Ochrona czystości powietrza — Oznaczanie wodorotlenku wapnia na stanowiskach pracy metodą płomieniowej absorpcyjnej spektrometrii atomowej

Title (EN)

Air purity protection — Determination of calcium hydroxide at workplaces by flame atomic absorption spectrometry

Step-by-step procedure

1. Status and condition of use

   PN-Z-04497:2018-09 current (card as of 04.10.2026); not used in the presence of other calcium compounds.

2. Sampling

   Inhalable and respirable fraction simultaneously on filters in fraction separators (CIOP procedure).

3. Mineralisation

   Concentrated nitric acid, hot, to dry residue (twice), solution in dilute acid with Cs and La; in parallel a blank from a clean filter (CIOP procedure).

4. Measurement

   F-AAS, 422.7 nm, air–acetylene flame; calcium calibration curve 0.50–20.00 µg/ml (CIOP procedure).

5. Result

   Separately for each fraction, conversion of calcium to calcium hydroxide (1.849) and comparison with the NDS of 2 and 1 mg/m³ (Journal of Laws 2026 item 447).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Operations with concentrated acids — in protective clothing and under a fume hood (CIOP procedure); acetylene flame of the spectrometer
• TECHNICAL NOTE: with other calcium compounds in the air the result of the method is not a result for calcium hydroxide (PKN card)

Frequently asked questions