Haze let us know the PM2.5 mask, SARS and novel coronavirus pneumonia (NCP) let us know the N95 mask. But do we really understand the mask? Why is the N95 mask called N95? Not N97? N98? Do you know these questions? In fact, there is a test of medical masks called filter efficiency rating. In detail, the filtration efficiency of non-oil particles was evaluated under the condition of gas flow rate of 85 L/min. Specific can be divided into three grades: ≥95%, ≥99%, ≥99.97%. And that’s why the N95 is named.
Currently, the masks we use include medical masks and particle protective masks.
Medical masks mainly include: one-time use medical mask, medical surgical mask, and medical protective mask.
Particle protective masks include: daily protective mask, PM2.5 protective mask, and protective masks (with plus P100 filter cotton).
Although the mask is small, there is a a lot of knowledge, let’s learn about the mask from three aspects.
- Quality requirements for masks
- Method for detection of masks
- Usage scenarios and precautions of masks
Quality requirements for masks
1 Medical masks
1.1 EU Standard: EN 14683 – 2014
|Testing items||Type Ia||Type II||Type II R||Test method|
|pressure difference (Pa/cm²)||29.4||29.4||49.0|
|Hemodialysis (KPa)||non||non||≥16(120mmHg)||ISO 22609|
|Microbial cleanliness (cfu/g)||≤30||≤30||≤30||ISO 11737 – 1|
Remark: Test at least 5 samples. 32 masks, no more than 3 through the blood.
1.2 US Standard: ASTM F2100-2004
|performance index||Low barrier||Moderate barrier||High barrier|
|BFE(%) ASTM F2101|
(28.3LPM·3.0μm Glucose bacterial particles)
|Pressure difference (mmH2O/cm²)|
184.108.40.206 of MIL-M-36954C (8.0LPM)
|PFE(%) 0.1μm emulsion particle|
ASTM F1862, ISO 22609
|Flame resistance 16CFR Pat 1610||Class 1||Class 2||Class 3|
1.3 YY 0469 – 2004 (medical surgical mask)
|performance index||BFE(%)||PFE(%)||Obstruction (pa)||Hemodialysis (mmH2O)||Remarks|
|Requirement||95||30||49||120||dip water grade 3|
|coli group||Pseudomonas aeruginosa||Staphylococcus aureus||hemolytic streptococcus||fungus colony|
|≤20||No detection||No detection||No detection||No detection||No detection|
2 Particle protective masks
2.1 EU Standard EN 149:2001+ A1-2009
|Penetration rating||NaCl particle 95L/min|
Max value % – penetration
|NaCl particle 95L/min|
Max value % -productiveness
|Oil particle 95L/min|
Max value % – penetration
|Oil particle 95L/min|
Max value % -productiveness
2.2 US Standard: NIOSH Standards (Title 42 CFR Part 84)
Test material: NaCl & DOP Particle diameter: 0.3μm Test flow rate: 85L/min
|N95 / P95 / R95||5%||≥95%||35mm H2O|
|N99 / P99 / R99||1%||≥99%||35mm H2O|
|N100 / P100 / R100||0.03%||≥99.97%||35mm H2O|
Method for detection of masks
The quality requirements of the mask generally include two categories, the use requirements of the mask and the performance requirements of the mask.
There are some basic requirements for the use or different countries of the masks: the mask should cover the wearer’s mouth and nose, the mask should have good facial tightness, the surface of the mask must not be damaged or stained, the mask should meet certain grade of rubbing color fastness, the mask belt should meet certain breaking strength and so on.
|Colorfastness to crocking (dry and wet)||≥4|
|Formaldehyde content (mg / Kg)||≤20|
|PH value||4.0 ～ 8.5|
|Decomposed carcinogenic aromatic amines||forbidden|
|Ethylene oxide residue (μg / g)||≤10|
|The breaking strength of the mask strap and the joint of the mask||≥20N|
The performance requirements of masks are based on the relevant standards, whether for medical masks, or anti-particulate masks, the European Union and the United States standards have different performance requirements for masks, we should do the corresponding test according to the standards. Such as air permeability test, burning test, and wet resistance test and so on.
Spray rating tester, to determine the surface wetting resistance of fabrics, which may or may not have been given a water-resistant or water-repellent finish. Auto air permeability tester is used to determine the air permeability of fabric totally automatically. Crockmeter, electronic mode, to determine the color fastness of textiles to dry or wet. Textile tensile testing machine, to determine the physical and mechanical performance of tension, tearing, compression, bursting, rapture, flexibility, shear and peel, and seam slippage.
Usage scenarios and precautions of masks
|one-time use medical mask||medical surgical mask||medical protective mask|
|Recommend the daily use of the public and medical institutions.||Recommended for use in public places: buses, taxis, sanitation workers, suspected case patients, etc.|
Protect the patient’s wound from contaminated inflammation during the operation, and provide medical staff to prevent the isolation of blood and body fluids.
|Do not recommend excessive public protection.|
Use of confirmed cases of transfer. Use of fever clinic and isolation ward.
|daily protective mask||PM2.5 protective mask||protective mask|
(with plus P100 filter cotton)
|The protective effect is better than medical surgical mask, one-time use medical mask, it is recommended to wear suspected cases.|
It can be worn in personnel-intensive occasions or can be used as haze protection.
|It is not recommended in public use.|
The barrier ability of particulate matter is the same as that of medical protective mask, which can be used for haze protection, industrial dust prevention.
|The level of protection is higher than that of medical masks.|
Use in emergency condition, endotracheal intubation, endoscopic operation in patients or suspected patients.
One-time use masks are common on the market, although they are disposable, but can be used two to three times under the general life scene. For example, take a walk inside and outside the district, this use condition, take off the mask after going home, put it in a ventilated environment, naturally dry and dry the moisture in it, prevent the accumulation of surface flora, so that it can be used for myself again. (Note: Disposable masks are not washable)
Recently, because novel coronavirus pneumonia (NCP) is very serious, many people’s habit of wearing masks is not correct. Therefore, for the NCP, we should pay attention to the following problems when wearing a mask.
1 Does a presidential gauze mask work?
It’s useless. After the role of SARS, in the implementation of the virus specialist environment professional implementation, the use of 12 or even 18 layers of cover, the result of particulate matter removal rate is only 96%, which is no less than 95% of the standardized one-time use mask, in the actual situation, it is impossible to wear a dozen layers of mask repeatedly.
2 Is the anti haze mask useful?
It’s useless. The design standard of anti haze mask is different from that of medical mask and cannot be used intercept the virus. If the inner filter material contacts virus, it is easy to be polluted again. In addition, anti haze masks are often with decorative, warm design. It is not recommended to use anti haze masks in epidemic situations.
3 Is valve mask useful?
Not recommended. The mask with valve function is mainly used for dust prevention. The valve is a “breathing valve” after leaving the dusty environment, which can breathe smoothly after opening. However, there is a risk of failure of this valve, and there is a large particle stuck situation, it can not prevent the virus inhalation.
4 Is it more useful to wear two disposable masks?
More does not mean that the efficiency of particle prevention will be improved. Some people are afraid that the mask is thin, it is unnecessary to wear two disposable masks. Because relevant experiments confirm that the “interception rate” of overlapping disposable masks to viruses is also 95%. Moreover, the double-layer mask causes the respiratory resistance to increase greatly, which will produce the discomfort of “suffocation”.