Does KN95 mask breathing valve affect the protective effect?

Update:30 Jul 2020

1. Is there a difference between KN95 and N95? KN95 is […]

1. Is there a difference between KN95 and N95?

KN95 is one of the levels specified in the Chinese standard GB2626-2006. N95 is one of the levels specified in the American standard 42 CFR 84. N95 masks are actually respirators. Respirators are a kind of respiratory protective equipment. Compared with ordinary masks, the design fits the face more closely and can filter the particulate matter in the air very effectively. Among them, N means Not resistant to oil, which can be used to protect non-oily suspended particles; 95 means that the filtration efficiency is greater than or equal to 95%, indicating that after careful testing, this respirator can block at least 95% of very small (0.3 Micron level) test particles.

In terms of design, if ranked according to the priority of the wearer's own protection capabilities (from high to low): N95 masks>surgical masks>ordinary medical masks>ordinary cotton masks. If worn correctly, the filtering capacity of N95 is better than ordinary masks and medical masks. The technical requirements and test methods of these two levels are basically the same, and the filtration efficiency reaches 95% under the corresponding standards.

2. How long can KN95 masks be used?

At present, foreign countries, including the World Health Organization (WHO), have not made clear conclusions on the best wearing time of N95 masks, and my country has not yet made relevant regulations on the use time of masks. Some researchers have done related studies on the protection efficiency and wearing time of KN95 medical protective masks. The results show that KN95 masks are worn for 2 days, the filtration efficiency remains above 95%, and the respiratory resistance does not change much; the filtration efficiency decreases to 94.7 after wearing for 3 days. %. The advice given by the US Centers for Disease Control and Prevention is that when there is no sufficient supply of masks, as long as the equipment is not obviously soiled or damaged (such as creases or tears), it can be considered for reuse.

When the following situations occur, the mask should be replaced in time: 1. When the respiratory impedance increases significantly; 2. When the mask is damaged or damaged;

3. When the mask cannot be closely attached to the face; 4. The mask is contaminated (for example, when it is stained with foreign objects such as blood stains or droplets); 5. It has been used in individual wards or in contact with patients (because the mask has been contaminated).

3. Does the presence of a breathing valve affect the protective effect?

Generally speaking, KN95 is divided into two types with or without exhalation valve. For people suffering from chronic respiratory diseases, heart disease or other diseases accompanied by breathing difficulties, using KN95 respirators may make it more difficult for the wearer to breathe, so using N95 masks equipped with an exhalation valve can make them breathe easily Some, and help reduce heat buildup. The design of the exhalation valve is very delicate, with several layers of flaps. When inhaling, the flap will close tightly to ensure that no particles enter. When you exhale, the flap will open, letting out the hot and humid air. At the same time, there is a soft flap inside to ensure that no small particles enter.

contact us