Before the pandemic happened, masks like the surgical mask had been used widely in hospitals. Be it in operations or other medical procedures, the surgical mask was the mask to go. With the pandemic, the most effective masks to be worn are the N95 mask and the surgical mask. This is because they provide the protection that people need.
Unlike the N95 mask, the surgical mask is loose-fitting. It means that there is a great potentiality for any form of leakage. However, this potentiality of leakage does not invalidate the ability of the surgical mask in filtering free-floating particles in the air. Also, a surgical mask is regulated by the Food and Drug Administration (FDA).
You may notice that surgical masks look the same. They may look the same but it all goes down to filtration and its ability to be an effective barrier against particles. This filtration and ability to be an effective barrier is called protection ratings. A surgical mask may have a distinct protection rating. Meaning, there is an extent as to how effective a surgical mask in filtering particles.
Like the N95 mask, a surgical mask is a medical mask that carries the classification generated by the American Society of Testing and Materials (ASTM). The ASTM is responsible for creating standards with the aim of elevating the efficiency and protection of products like the surgical mask.
ASTM has established levels for the surgical mask. There are three levels corresponding to the efficiency and performance of a surgical mask. With the pandemic, people will always have this notion that the higher the number, the more efficient a product is. ASTM level 3 surgical mask is indeed the most efficient because it filters up to 98% of bacteria that are 3.0 microns in size.
What should a surgical mask have to have in order to gain the ASTM level 3 rating?
The ASTM standards are being followed by the FDA. These standards are the standard followed in the United States. The ASTM level 3 category for a surgical mask is the highest level. With the level it suggests, a surgical mask must possess the maximum quality fit for a level 3. Here are the standards for a surgical mask:
- Bacterial Filtration Efficiency
Bacterial Filtration Efficiency or BFE determines the efficiency of a surgical mask in straining out bacteria after being exposed to an environment with bacteria-infested aerosol. The ASTM designated a testing size of 3.0 micron. In order for a surgical mask to have a level 3 rating, it must be able to filter up 98% of bacterial particles. It goes the same for the level 2 surgical mask and for level 1 surgical mask, it is 95% filtration efficiency.
- Particulate Filtration Efficiency
Particulate Filtration Efficiency or PFE pertains to measuring the effectiveness of a surgical mask in filtering particles with a size range of 0.1 to 5.0 microns. A level 3 surgical mask is able to filter particles with 0.1 microns in size with 98% efficiency. It goes the same for level rating 2 and for level rating 1, it is 95%.
- Delta P
Delta P or Differential Pressure is responsible for identifying the breathability of a surgical mask. Through this standard, Delta P gauges the resistance of air that flows off the surgical mask. The unit for this measurement is mm H2O/cm2 or read as millimeters in water per square centimeter. A level 3 surgical mask has a Delta P of <5.0 or less than 5.0. The lower the number, the more breathable a surgical mask is. Since the level 1 surgical mask has a Delta P of <4.0 or less than 4.0, it is more breathable than the level 3 surgical mask.
- Fluid Resistance to Synthetic Blood
Fluid resistance testing tests the capability of a surgical mask to limit the quantity of fluid that goes through the layers of the mask. This may come in either a sudden spray or splash of the fluid. For an ASTM level 3 surgical mask, the pressure must be at 160 mm Hg which corresponds to high pressure. This high pressure may occur in surgeries. For level 2 surgical mask, it is at 120 mm Hg. For level 1 surgical mask, it is at 80 mm Hg.
- Flame Spread
Flame spread of flame resistance is measured since hospitals house some of the most flammable chemicals like the oxygen gas O2. A surgical mask with levels 1, 2, and 3 are all classified as Class 1. This means that regardless of the ASTM level rating, the surgical mask can endure flame exposure within a distinct space within three seconds.
All ASTM levels of the surgical mask are ISO certified. Therefore, a surgical mask that passed the standards of the ASTM is tested to be of international standard. This also means that the surgical mask does not harm anyone who wears it and does not develop any form of skin irritation.
With the established standards, the ASTM level 3 surgical mask is proven to obtain a higher value of protection. However, once torn or damaged, the ASTM level 3 surgical mask is good for nothing. Medical experts have been reminding people not to reuse or repurpose the used surgical mask. This is due to a fact that the used mask can endanger the wearer and be in contact with any harmful microorganisms.