Quality Detection and Specification for Use of Medical Masks or N95 Masks – for the Novel Coronavirus

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.

Medical masks

Particle protective masks include: daily protective mask, PM2.5 protective mask, and protective masks (with plus P100 filter cotton).

Particle protective masks

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 itemsType IaType IIType II RTest method
BFE(%)≥95≥98≥98
pressure difference (Pa/cm²)29.429.449.0
Hemodialysis (KPa)nonnon≥16(120mmHg)ISO 22609
Microbial cleanliness (cfu/g)≤30≤30≤30ISO 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 indexLow barrierModerate barrierHigh barrier
BFE(%) ASTM F2101

(28.3LPM·3.0μm Glucose bacterial particles)

≥95≥98≥98
Pressure difference (mmH2O/cm²)

4.4.1.2 of MIL-M-36954C (8.0LPM)

<4.0<5.0<5.0
PFE(%) 0.1μm emulsion particle

ASTM F2299

Not required≥98≥98
Hemodialysis (mmHg)

ASTM F1862, ISO 22609

80120160
Flame resistance  16CFR Pat 1610Class 1Class 2Class 3

1.3 YY 0469 – 2004 (medical surgical mask)

performance indexBFE(%)PFE(%)Obstruction (pa)Hemodialysis (mmH2O)Remarks
Requirement953049120dip water grade 3
bacterial colony

CFU/g

coli groupPseudomonas aeruginosaStaphylococcus aureushemolytic streptococcusfungus colony

CFU/g

≤20No detectionNo detectionNo detectionNo detectionNo detection

2 Particle protective masks

2.1 EU Standard EN 149:2001+ A1-2009

Penetration ratingNaCl 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

FFP 120≥80%20≥80%
FFP 26≥94%6≥94%
FFP 31≥99%1≥99%

2.2 US Standard: NIOSH Standards (Title 42 CFR Part 84)

Test material: NaCl & DOP  Particle diameter: 0.3μm  Test flow rate: 85L/min

Gradepenetrationfilter efficiencyobstruction
N95 / P95 / R955%≥95%35mm H2O
N99 / P99 / R991%≥99%35mm H2O
N100 / P100 / R1000.03%≥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 value4.0 ~  8.5
Decomposed carcinogenic aromatic aminesforbidden
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.

mask tester

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 maskmedical surgical maskmedical 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 maskprotective 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”.

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