Civilian Masks

Medical Masks

How much protection can a mask provide?

Time: Author: Views:16120 From: Jingde

Masks:

It is a loose disposable mask that can form a physical barrier between the user's mouth and nose and create potential contamination in the vicinity. It has different thicknesses and variable characteristics to prevent liquid contact. These functions also affect the permeability and protection level. Effectively prevent large particles from splashing and spraying. It does not filter or block very small particles in the air, which can be spread by coughing, sneezing or certain medical procedures.


Face Masks


Respirator:

Respirator N95 mask, it will filter out 95% of particles larger than 3 microns.

The respirator protects you from:

powder

Pollution

bacterial

virus

allergen

It cannot protect against the following substances:

Oil-based ingredients

gas

Fabric mask

Many traditional textile manufacturers are willing to temporarily convert their production into reusable textile masks instead of using these materials, because the demand for standard non-woven surface materials unexpectedly increases to assist production, so the supply of these materials is extremely inadequate. Scientists are testing everyday items to find the best protective measures to prevent coronavirus. Pillow cases, flannel pajamas and origami vacuum bags are candidates.


Mask performance evaluation:

BFE (Bacterial Filtration Efficiency)

When faced with an aerosol containing bacteria, it can measure the filtering effect of the mask on bacteria. The bacterial filtration rate of medium and high protective masks exceeds 98% to 99%.


PFE (Particle Filtration Efficiency)

The submicron particles of the mask measure its filtering effect by the fact that the virus is similarly filtered. As the percentage increases, it can be seen that the efficiency of the mask is very high. ASTM F2100-07 indicates that the particle size used is 0.1 microns.


Fluid resistance

It reflects the ability of the mask to minimize the amount of fluid flowing from the outer layer to the inner layer due to splashes or splashes.


Differential pressure (Delta P)

It measures the air flow resistance of the mask and is an objective measure of breathability. Masks with a P value less than 4.0 are considered acceptable, and masks with a P value less than 2.0 are considered very good.


Surgical mask


Can a mask provide protection?

Research experts have tested various fabrics and materials using a particle size analyzer, which can measure particle size and concentration. Then, they compared the "filtration efficiency" of multiple layers of each material with different aerosol particle sizes ranging from a few nanometers to 400 nanometers. The researchers found that the scarf and headscarf layers were unable to filter aerosols. Pillowcase fabrics will produce better results depending on the yarn frequency. The researchers found that pillowcases with a 600-line density filter are better than 400-line. The test team found that the effectiveness of the masks was varied. They also found that in some fabrics, two layers provide much less protection than four layers.


600 linear density double pillowcases provide 22% protection

4-layer pillowcase with a linear density of 600, providing about 60% protection

Coarse wool double weft yarn provides 21% filtration rate

Coarse wool 4-layer scarf provides 48.8% filtration rate

Among them, the 100% cotton double-layer headscarf is the most unsuccessful, only providing a filtration rate of 18.2%.

100% cotton provides 19.5% filtration for 4-layer headscarf

According to different studies, the filtration rate of certain fabric masks can reach or exceed that of surgical masks, with a filtration rate between 70% and 79%, while the filtration rate of homemade masks made of lighter fabrics is as low as 1 %.


In another study, experts tested breathability and particle filtration. Although kitchen towels and vacuum bags absorb the most particles, they are also the most difficult to breathe. When using two layers of wipes, the breathability is twice that of surgical masks.


result:

Not surprisingly, surgical masks perform best and capture 97% of 1% bacteria. However, each material filters at least 50% of the particles. The answer lies in breathability. The difficulty of wearing a mask to breathe is an important factor, which will affect the comfort and wearing time of the mask.

Mask knowledge

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