Validating the use of a multi-fraction sampler for recovering inhalable and respirable dust mass, and metals in workplace air: Application to welding environments
Bibliographic record
Abstract
,This study validated the Disposable Respirable Sampler (DRS) as an integrated, multi-fraction sampler for simultaneous measurement of inhalable and respirable aerosol mass and associated metals in occupational welding environments, following ISO 7708 definitions. The DRS consists of a disposable body with polyurethane foam, a PVC chimney, and a 25 mm PVC filter. Gravimetric analysis of the filter represents the respirable fraction, while the foam and chimney combined represent the inhalable fraction. Validation included laboratory gravimetric and chemical testing, followed by field sampling at three welding shops in Prince George, BC. Gravimetric tests in a controlled chamber (25 °C, 50% RH) confirmed mass stability of all components over 3–4 weeks. DRS limits of detection (LOD) and quantification (LOQ) were 22/72 µg (filter), 41/137 µg (foam), and 183/610 µg (capsule), within ISO 15767 criteria. Laboratory validation using certified stainless-steel welding fume (SSWF) reference material at four concentration levels (0.1, 0.5, 1, and 2 × TLV) established strong analytical performance. Analytical recovery values for the chimney + foam component ranged from 91.5–107.3% for Cr, 93.5–102.9% for Fe, 87.7–98.9% for Mn, and 90.6–107.1% for Ni, with method repeatability, expressed as the coefficient of variation (CV) ranged from 1.5% to 6.6%, and intermediate reproducibility between 3.0% and 9.7%, all within acceptable thresholds. Recoveries for the filter fraction ranged from 91.7–103.6% for Cr, 92.2–103.1% for Fe, 90.6–97.3% for Mn, and 91.2– 99.8% for Ni, with method repeatability values between 0.8% and 5.4% and reproducibility between 1.0% and 6.4%, confirming robust analytical precision. Field validation across three welding shops revealed substantial to excellent agreement with reference methods for gravimetric measurements (Concordance Correlation Coefficients: 0.767–0.964). For inhalable dust, DRS performance varied: 114% of reference values at Cariboo (CCC = 0.827), 72.6% at GAP (CCC = 0.287), and 97.6% at Stinger (CCC = 0.964), with a pooled mean of 91.5%. Respirable dust results were more consistent, with DRS measuring 0.156, 0.68, and 0.374 mg/m³ versus cyclone values of 0.13, 0.594, and 0.334 mg/m³, reflecting a pooled 15.8% oversampling bias that was consistent and predictable across all sites. Metals analysis showed no statistically significant differences between samplers (p > 0.05) for either fraction, with high correlation coefficients (R² ≥ 0.90) for iron, manganese, copper, and zinc, indicating that gravimetric discrepancies were not due to collection efficiency. This validation confirms the DRS as a reliable, field-ready tool for dual-fraction aerosol sampling in occupational welding environments. The sampler demonstrates minimal capsule wall deposition (
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".