N95 mask
What is N95 mask?
- N95 is a particulate filtering facepiece respirator. It meets the U.S. National Institution for Occupational Safety and Health (NIOSH) standard of air filtration. It filters 95% of airborne particles. It provides mechanical filtration that protects against particulates but not against gases or vapors. N95 masks do not have resistance to oil. There is another type of mask P95, for this purpose. In the Covid-19 pandemic situation, N95 masks are suggested to be used by the doctors and nurses who are treating covid patients.
- N95 respirators are equivalent to FFP2 respiratos of EU and KN95 respirators of China. But they have difference in filter efficiency, test agent, flow rate and permissible pressure drop.
Where N95 masks should be used?
- N95 is approved as a medical device. It is approved by NIOSH and cleared by “food and Drug Association”. They may be also labeled as ‘Surgical N95’, ‘Medical respirators’, ’Heealthcare respirators’.
- N95 masks are not for public use. According to ‘Occupation Safety and Health Administration’ of USA This mask will only be used by health care workers who will be handling patients who are suspected or confirmed to be infected with covid-19.
Construction of N95 mask:
- It is a fine mesh of synthetic polymer fiber (generally nonwoven polypropylene).
- It is produced by melt blowing method.
- The inner layer filters the hazardous particles through different mechanisms.
N95 mask has a very close facial fit to prevent any leakage. It
is designed to form a seal around the nose and mouth. Although it cannot filter
100% airborne particle but it has an efficiency of 95%.
Broadly speaking, generally N95 mask has 2 layers.
The outer layer:
- Citric acid 2% w/w
- PH lowering agent
The inner layer (treated with metal ion)
- Copper 1.6% w/w
- Zinc 1.6% w/w
- They form ionic bond with influenza virus.
The outer and inner layer go through different treatment
processes. As a result they can independently inactive virus through different
mechanisms.
More specifically speaking N95 masks are divided into 4 layers.
- Outer layer – Spun bond polypropylene
- A second layer – Cellulose/polyester
- A third layer – Melt blown polypropylene filter material
- An inner (fourth) layer – Spun bound polypropylene
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| Layers of N95 mask |
Performance data of N95 mask:
KN95 mask:
- Along with N95 mask, another type of mask has been highly used in this pandemic and that is KN95 mask. This mask was originally manufactured in China. It is considered somewhat equivalent to N95 mask. But there are some differences between them. In some criteria, KN95 mask provide less protection compared to N95 mask.
- KN95 masks need approval from ‘Food and Drug Association’ (FDA) and they must fulfill 95% filtration criteria. They should also pass the ‘Fit testing’ that includes testing of the air inside and outside the mask and also fitting of the mask around the face.
What KN95 are made from?
Like N95, KN95 are also made from multiple layers of synthetic
materials. There are multiple layers of non-woven fabric and melt blown fabric
that provide protection against airborne particles.
Performance data of KN95 mask:
Surgical mask:
- It is intended to protect a person from the liquid droplet and aerosol from the wearer’s mouth and nose. It will create a physical barrier between the wearer and the person in front of him. But the wearer can still inhale airborne bacteria and viruses. Which means it provides only one way protection.
- Surgical mask blocks only large particles. Prevents droplets, splashes, sprays etc. from reaching other person’s nose and mouth.
- Surgical mask cannot block small particles. Also it cannot provide complete protection against germs due to its loose fitting around the mouth and nose.
Construction:
It is made of non-woven fabric that is made using melt blowing
method.
Comparison between N95, KN95, surgical masks:
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