[Investigation of the Filter Performance in a Sample of Standardised Particle-filtering Half Masks]

Area of Science:

• Medical Devices
• Public Health
• Respiratory Protection

Background:

• A simplified approval process led to many particle-filtering half masks entering the German market.
• The Robert Koch Institute (RKI) recommends FFP2 masks (≥94% filter performance) for caring for SARS-CoV-2 patients.
• 15 particle-filtering half masks with varying specifications were evaluated.

Purpose of the Study:

• To assess the filter performance of particle-filtering half masks available on the German market.
• To determine compliance with the FFP2 standard recommended for healthcare settings.
• To identify masks that may not offer adequate protection.

Main Methods:

• Masks were tested in an airtight chamber using radioactive particles (0.6 ± 0.4 µm).
• An artificial lung simulated inhalation through the mask and an unfiltered port.
• Gamma camera measurements quantified particle deposition to calculate filter performance.

Main Results:

• Five out of 15 masks (33.3%) exhibited filter performance below the 94% FFP2 threshold.
• Measured filter performances for non-compliant masks ranged from 71.8% to 92.2%.
• Significant variations in filtration efficiency were observed among tested masks.

Conclusions:

• A substantial proportion of masks failed to meet the FFP2 standard crucial for SARS-CoV-2 patient care.
• The findings suggest a need for rigorous post-approval monitoring of respiratory protective equipment.
• Regulatory authorities should conduct a comprehensive review of already approved masks.