Interlaboratory comparison of particle filtration efficiency testing equipment

Area of Science:

• Materials Science
• Metrology
• Public Health

Background:

• Particle filtration efficiency (PFE) is crucial for face mask performance.
• Standard PFE testing commonly uses sodium chloride aerosols.
• Quantifying measurement uncertainty is essential for reliable PFE data.

Purpose of the Study:

• To quantify the precision and bias of PFE testing methods through interlaboratory comparisons.
• To assess the contribution of between-laboratory variability to overall measurement uncertainty.
• To evaluate the impact of material properties on PFE.

Main Methods:

• Conducted multiple interlaboratory comparisons of PFE using sodium chloride.
• Utilized log-penetration as a surrogate metric for PFE.
• Analyzed data to determine reproducibility intervals and between-laboratory contributions.
• Tested filtration materials with variations in layers, charge, and basis weight.

Main Results:

• Expanded reproducibility intervals for log-penetration were consistent across most samples, averaging ~26% of the nominal value.
• Between-laboratory variability significantly increased reported uncertainties, often doubling them.
• Material property variations (layers, charge, basis weight) showed constant quality is a reasonable approximation for identical materials.

Conclusions:

• Significant between-laboratory differences exist in PFE testing, necessitating further investigation into causes.
• Ongoing interlaboratory studies are vital for improving the reliability of PFE measurements.
• While material variations impact PFE, consistent quality can be assumed for similar materials under specific conditions.