Round-Robin Tests with Relocatable Coverslips Improve Asbestos Fibre Counting

Area of Science:

• Occupational Health
• Environmental Science
• Analytical Chemistry

Background:

• Asbestos fibre counting accuracy is crucial for health and safety.
• Phase-contrast microscopy methods are prone to analyst-dependent variations.
• Standardized proficiency testing is needed to ensure reliable asbestos analysis.

Purpose of the Study:

• To evaluate analyst proficiency in asbestos fibre counting using relocatable coverslips.
• To identify and quantify sources of error in asbestos fibre enumeration.
• To establish performance benchmarks for asbestos analysis.

Main Methods:

• Distribution of amosite and chrysotile asbestos sample slides with relocatable coverslips to voluntary analysts.
• Conducting multiple rounds of proficiency testing, with analysts reporting fibre counts and positions.
• Evaluation of reported data against verified fibres to calculate proficiency scores and identify error types.

Main Results:

• Amosite fibre counting showed generally good results, with a major error in counting fibres shorter than 5 µm.
• Chrysotile fibre counting demonstrated initial low performance, with significant improvement over rounds but not consistently.
• Oversight-missing fibres were the primary error source for chrysotile, while short fibres impacted amosite counts.

Conclusions:

• Relocatable coverslips facilitate proficiency assessment in asbestos fibre counting.
• Analyst performance in asbestos analysis can be improved through targeted training and feedback.
• Consistent accuracy in chrysotile fibre counting remains a challenge, requiring further investigation into error reduction strategies.