What is the difference in protection between level 1 and level 3 surgical masks?
There are three levels of ASTM masks -- Levels 1, 2, and 3; practically speaking most surgical masks are either Level 1 or Level 3. Surgical masks are assessed using American Society of Testing and Materials American Society of Testing and Materials (ASTM) Standards.
(When choosing surgical masks, look for the ASTM rating on the box to ensure claims made regarding filtration and fluid resistance are valid.)
Some of the key measures are:
- Particle filtration efficiency — measures the percentage of particles larger than 1 micron that are filtered by the mask.
- Bacterial filtration efficiency —measures how well the mask filters out bacteria when challenged with a bacteria-containing aerosol. The test measures the percentage of bacteria greater than 3 microns that are filtered by the mask.
- Fluid resistance — measures the resistance of the mask to penetration by high velocity synthetic blood. This is more important for healthcare practitioners who work where heavy to moderate amounts of fluid, spray, and/or aerosols are produced such as during surgery or other medical procedures.
- Breathability — measures the face masks’s resistance to airflow to assess breathability. Lower breathing resistance indicates better comfort.
|Measure||Standard||ASTM Level 1 Mask||ASTM Level 3 Mask|
|Particle Filtration Efficiency 1 micron||ASTM F2299||≽95%||≽98%|
|Bacterial Filtration Efficiency 3 micron||ASTM F2101||≽95%||≽98%|
|Fluid Resistance||ASTM F1862||Lower (80 mmHg)||Higher (160 mmHg)|
|Breathability||MIL-M-36954 C: ΔP||<4 mm H20Lo||<5 mm H20|