🌿 Respirable fraction of the aerosol (dust) at workplaces — gravimetric method
In short
Drawing of a known volume of air through a sampler with a pre-separator (e. The test is performed according to PN-Z-04508:2022-05 + Ap1:2022-08; Quantity determined: concentration of the respirable fraction of the aerosol X [mg/m³]. The procedure comprises 5 steps; it is used for: Assessment of the exposure to pneumoconiosis-causing dusts: mining, stonemasonry, foundries, the manufacture of building materials and ceramics, the working of stone and concrete, Measurements required by the regulation of the Minister of Health on tests and measurements of harmful agents — comparison with the NDS for the respirable fraction, Sampling for the determination of the respirable fraction of crystalline silica (an obligation of simultaneous determination with many dusts).
At a glance
- Standard: PN-Z-04508:2022-05 + Ap1:2022-08
- Category: Environment
- Procedure steps: 5
- Quantity determined: concentration of the respirable fraction of the aerosol X [mg/m³]
- Respirable convention (EN 481): log-normal distribution, median 4.25 µm, GSD 1.5; 50 % of the particles of D = 4 µm
- Formula: X = (m2 − m1 − B)/V; m in mg, V in dm³
Overview
The respirable fraction is — according to the regulation on the maximum admissible concentrations (NDS) and the maximum admissible intensities (NDN) — the fraction of the aerosol entering the respiratory tract which creates a hazard to health after deposition in the region of gas exchange, defined in accordance with the standard PN-EN 481. EN 481 describes the respirable convention as a share of the inhalable convention given by a cumulative log-normal distribution with a median of 4.25 µm and a geometric standard deviation of 1.5; converted to the whole of the airborne particles, at an aerodynamic diameter of 4 µm 50 % is collected, at 7 µm about 9 %, at 10 µm about 1 %. These are the particles reaching the unciliated airways (the pulmonary alveoli) — the most significant for the risk of pneumoconiosis.
The standard PN-Z-04508:2022-05 (with the corrigendum Ap1:2022-08) gives the method of determining the respirable fraction of the aerosol at workplaces by the gravimetric method, applied during the control of the sanitary and hygienic conditions; it replaced the standard PN-91/Z-04030/06 concerning "respirable dust". The smallest determinable concentration depends on the type of sampler, the type of filter and the accuracy of the balance. For the risk of pneumoconiosis the most suitable is personal sampling in the breathing zone of the worker and the determination of the concentration of the respirable fraction. For many dusts the regulation requires the simultaneous determination of the concentration of the respirable fraction of crystalline silica — work under exposure to it belongs to the processes with a carcinogenic action.
Method principle
The air tested is drawn at a known volume flow rate over a specified time through a sampler containing a pre-separator and, behind it, a filtering medium (filter). The fraction of the coarse particles — not penetrating to the alveolar region of the lungs — is retained in the pre-separator, and the respirable fraction is deposited on the filter mounted in the sampler behind the pre-separator; the volume flow rate must correspond to the value for which the pre-separator realises the respirable convention. The mass of the aerosol retained is determined as the difference in the mass of the filter weighed after the sampling and before it, and the concentration is calculated as the ratio of that mass to the volume of the air drawn: X = (m2 − m1 − B)/V [mg/m³], taking into account the mean change of mass of the blank samples B. The preparation of the filters, the sampling, the transport and the storage are carried out in the same way as for the inhalable fraction.
Applications
- Assessment of the exposure to pneumoconiosis-causing dusts: mining, stonemasonry, foundries, the manufacture of building materials and ceramics, the working of stone and concrete
- Measurements required by the regulation of the Minister of Health on tests and measurements of harmful agents — comparison with the NDS for the respirable fraction
- Sampling for the determination of the respirable fraction of crystalline silica (an obligation of simultaneous determination with many dusts)
- Personal sampling in the breathing zone — the basis for the assessment of the risk of pneumoconiosis
- Control of the effectiveness of ventilation and of the measures limiting the raising of dust
Key parameters
| Parameter | Value |
|---|---|
| Quantity determined | concentration of the respirable fraction of the aerosol X [mg/m³] |
| Respirable convention (EN 481) | log-normal distribution, median 4.25 µm, GSD 1.5; 50 % of the particles of D = 4 µm |
| Formula | X = (m2 − m1 − B)/V; m in mg, V in dm³ |
| Limit of determination | depends on the sampler, the filter and the accuracy of the balance |
| Frequency of measurements (regulation of the Minister of Health) | once a year at > 0.5 NDS; once every 2 years at 0.1–0.5 NDS; carcinogenic dusts (including crystalline silica): every 3 months at > 0.5 NDS, every 6 months at 0.1–0.5 NDS |
| Reference conditions for the NDS concentrations | 20 °C, 101.3 kPa |
Standard
- Standard number
- PN-Z-04508:2022-05 + Ap1:2022-08
- Title (PL)
- Ochrona czystości powietrza — Oznaczanie frakcji respirabilnej aerozolu na stanowiskach pracy metodą grawimetryczną
- Title (EN)
- Air purity protection — Determination of the respirable aerosol fraction at workplaces by the gravimetric method
Step-by-step procedure
-
Preparation of the filters and of the blank samples
Condition the filters (or the filters with the cassettes) in a desiccator and weigh them (m1). Prepare blank samples for determining B. Check the balance with a mass standard; weigh each filter twice.
-
Assembly of the sampler
Mount the filter in the cassette behind the pre-separator (the cyclone), connect the pump and set the volume flow rate proper for the pre-separator used — on it depends whether the fraction sampled corresponds to the respirable convention. Measure the flow rate before the start.
-
Sampling
Place the sampler in the breathing zone of the worker (personal sampling) or at a stationary point; sample for the time following from the measurement strategy and from the required mass of dust on the filter. After the end measure the volume flow rate again; note the environmental conditions.
-
Transport, storage, weighing
Transport the cassettes closed, protecting the filter against loss of dust; condition under the same conditions and weigh (m2).
-
Calculation and assessment
Calculate X = (m2 − m1 − B)/V in mg/m³, determine the exposure index and compare it with the NDS for the respirable fraction; where the regulation so requires, hand over the filter for the determination of crystalline silica. Where the NDS is exceeded the employer takes measures without delay; for carcinogenic agents the risk is always large (medium only at a concentration ≤ 0.1 NDS).
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Analytical balance | for the differential weighing of the filters; check with a mass standard and of the drift during the series | — |
| Suction pump (personal or stationary sampling pump) | of a constant volume flow rate matched to the pre-separator; checked before and after the sampling | — |
| Sampler with a pre-separator for the respirable fraction | a cyclone for the respirable fraction with a filter cassette, fastened in the breathing zone | — |
| Filters | selected according to the further analysis — for ashing and the determination of silica neither PTFE nor glass fibre filters are used | — |
| Desiccator | conditioning of the filters before weighing | — |
| Devices for measuring the volume flow rate, the environmental conditions and the time | flow calibrator, thermo-hygro-barometer, stopwatch | — |
Health and safety (OHS)
- The respirable fraction of crystalline silica is a carcinogenic agent — sampling and handling of the filters with protection of the respiratory tract, without raising dust again
- Clean the cyclone after every sampling — a deposit of coarse particles changes its characteristics and may be transferred to the filter
- Fasten the personal pumps so that they do not restrict the movements of the worker and do not create a risk of catching
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-Z-04508:2022-05 + Ap1:2022-08 — “Air purity protection — Determination of the respirable aerosol fraction at workplaces by the gravimetric method”.
How does this method work?
The air tested is drawn at a known volume flow rate over a specified time through a sampler containing a pre-separator and, behind it, a filtering medium (filter). The fraction of the coarse particles — not penetrating to the alveolar region of the lungs — is retained in the pre-separator, and the respirable fraction is deposited on the filter mounted in the sampler behind the pre-separator; the volume flow rate must correspond to the value for which the pre-separator realises the respirable convention.
What is the measuring range and accuracy?
Quantity determined: concentration of the respirable fraction of the aerosol X [mg/m³]; Respirable convention (EN 481): log-normal distribution, median 4.25 µm, GSD 1.5; 50 % of the particles of D = 4 µm; Formula: X = (m2 − m1 − B)/V; m in mg, V in dm³; Limit of determination: depends on the sampler, the filter and the accuracy of the balance.
How long does the test take?
The procedure comprises 5 steps. The standard does not give a duration for every stage — the laboratory's own procedure decides.
What equipment is required?
Analytical balance, Suction pump (personal or stationary sampling pump), Sampler with a pre-separator for the respirable fraction, Filters, Desiccator, Devices for measuring the volume flow rate, the environmental conditions and the time.
Where is this test used?
Assessment of the exposure to pneumoconiosis-causing dusts: mining, stonemasonry, foundries, the manufacture of building materials and ceramics, the working of stone and concrete; Measurements required by the regulation of the Minister of Health on tests and measurements of harmful agents — comparison with the NDS for the respirable fraction; Sampling for the determination of the respirable fraction of crystalline silica (an obligation of simultaneous determination with many dusts); Personal sampling in the breathing zone — the basis for the assessment of the risk of pneumoconiosis; Control of the effectiveness of ventilation and of the measures limiting the raising of dust.
What safety precautions apply?
The respirable fraction of crystalline silica is a carcinogenic agent — sampling and handling of the filters with protection of the respiratory tract, without raising dust again; Clean the cyclone after every sampling — a deposit of coarse particles changes its characteristics and may be transferred to the filter; Fasten the personal pumps so that they do not restrict the movements of the worker and do not create a risk of catching.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-Z-04508.