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Performance Comparison of Four Portable FTIR Instruments for Direct-on-Filter Measurement of Respirable Crystalline
Elizabeth L Ashley1, Emanuele Cauda1, Lauren G Chubb1
1Office of Mine Safety and Health Research, Pittsburgh Mining Research Division (PMRD), National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC), Pittsburgh, PA, USA.
Researchers developed a new field-based method for monitoring respirable crystalline silica exposure in mines. This direct-on-filter analysis using portable Fourier transform infrared instruments provides precise and reproducible results, aiding in miner safety.
Area of Science:
- Occupational Health and Safety
- Analytical Chemistry
- Environmental Monitoring
Background:
- Respirable crystalline silica exposure is a significant occupational hazard, particularly for miners, leading to potentially fatal silicosis.
- Current silica exposure assessment relies on laboratory analysis of filter samples, causing delays in results.
- A timely, field-based monitoring method is needed to empower mine operators with immediate exposure data.
Purpose of the Study:
- To evaluate the performance of portable Fourier transform infrared (FTIR) instruments for direct-on-filter (DoF) analysis of respirable crystalline silica.
- To determine the reproducibility and precision of measurements obtained from these field-based instruments.
- To support the development of a new, rapid silica monitoring technique for occupational settings.
Main Methods:
- Four commercially available portable FTIR instruments were tested.
- Filter samples containing varying concentrations and compositions of respirable crystalline silica were analyzed.
- Instrument-to-instrument variability, short-term and extended-term reproducibility, and statistical significance of measurements were assessed.
Main Results:
- Measurements showed low variability between instruments (±4.1% for high-purity silica, ±3.0% for varying mineral compositions).
- Mean coefficients of variation for repeated analyses did not exceed ±1.6% (short-term) and ±2.4% (extended-term).
- Mixed model analysis confirmed no statistically significant change in average measurements over extended periods for any instrument.
Conclusions:
- The evaluated portable FTIR instruments demonstrated the ability to provide precise and reproducible direct-on-filter (DoF) analysis of respirable dust samples.
- This field-based silica monitoring technique shows promise for timely exposure assessment in mining environments.
- The findings support the adoption of FTIR-based DoF analysis as a viable alternative to traditional laboratory methods for occupational silica monitoring.
