The use of KN95 masks for epidemic prevention on the front lines by medical personnel is the subject of heated debate. When many individuals purchase masks, they frequently find them labeled “KN95” rather than “N95.”
Exists a distinction between KN95 and N95 masks? Can the KN95 mask be used for first-line defense? In response to the SARS epidemic, Science and Technology Daily interviewed Professor Jin Xiangyu, deputy director of the Engineering Center for Industrial Textiles of the Ministry of Education and director of the Department of Nonwoven Materials and Engineering at Donghua University, who oversaw the “Development of anti-SARS virus protective Textiles” project.
Exists a distinction between KN95 and N95 masks?
Jin: The respirator certification grade in the United States is N95. The National Institute for Occupational Safety and Health has certified it. This type of mask is named N95 because it can filter out more than 95 percent of non-oily particles (aerosols) at a specified gas flow rate (85L/min). If it can filter more than 99 percent of particulate matter (aerosol), it is called a N99 mask. In addition, corresponding to N95, KN95 is a mask certified by China’s GB2626-2006 respiratory protective equipment self-priming filter type anti-particulate respirator standard.
KN95 and N95 masks have the same level of protection, but they follow different national testing standards. KN95 masks comply with the Chinese standard, and N95 masks comply with the American standard. The protection efficiency of both masks against non-oily particles (experimental sodium chloride particles) is not less than 95 percent . s2. Can KN95 mask be used for first-line protection?
Jin: Both KN95 and N95 masks include medical and non-medical varieties. KN95/N95 masks with the “medical” mark can be used for first-line protection of medical personnel during the fight against the epidemic, whereas masks without the “medical” mark are not recommended for medical personnel and can be used by ordinary people. In accordance with GB19083, masks above grade 1 are not only capable of 95 percent filtration, but also prevent liquid penetration. They can be utilized in a variety of medical procedures.
If the published content is accurate and the health authorities have confirmed that this type of product cannot be used for the protection of first-line medical staff in hospitals designated for COVID-19 treatment, then KN95 masks may be non-medical.
Why are KN95 and N95 masks effective against viruses?
Jin Xiangyu: Viruses are typically found attached to droplets, dust, dander, and other particles in the air. The filtering mechanism of KN95 and N95 masks is to block these fine particles through the mask’s high-performance filtering layer and create a protective barrier.
Therefore, when wearing KN95/N95 respiratory protective equipment self-priming filter type anti-particulate respirator mask, attention should be paid to the tightness, should be close to the face, never leave a “convenient door” for viruses and bacteria, it is recommended to cautiously use masks with “breath valve” type.
What is the distinction between non-medical and medicinal KN95/N95 masks?
Jin Xiangyu: The primary distinction is the hydrophobic outer surface of medical masks. The medical surgical masks of GB19083-2010 and YY0469-2011 specify the requirement of “synthetic blood penetration” and the parameter index of “surface moisture resistance,” thereby defining the protective effect of medical protective masks on blood and body fluids. In general, it is as though water that drips onto a lotus leaf will roll off. The liquid cannot be absorbed into the surface of the mask, which can block alcohol and blood frequently handled by medical personnel and slow their penetration. Non-medical KN95/N95 masks do not receive this specific treatment.
The filter layer of KN95 and N95 protective masks, which is comprised of polypropylene melt-blown microfibre electrode material, provides the greatest level of protection. The exterior surface of the mask has not been hydrophobically treated, and contact with water and alcohol during application will degrade the material’s structure, resulting in a significant reduction in filtration efficiency. In addition, blood frequently contains bacteria, viruses, etc., and hospital application scenarios determine that medical personnel are exposed to the blood environment of patients. Therefore, it is necessary that the surface of surgical masks be hydrophobic. Normal individuals are likely to encounter alcohol, and the risk of blood exposure is not negligible; however, as long as the mask is regularly replaced, its exterior is also innocuous without this treatment.
What protective impact does the KN95/N95 mask with breathing valve have?
Jin Xiangyu: KN95/N95 masks are also available with and without breathing valves. For masks, air permeability and filtration efficiency are always at odds. If the filtration effect is effective, you will frequently feel stifled. The purpose of the breathing valve is to alleviate breath-holding.
Breathing valve and suction valve is a mechanical switch, inspiratory close, EXPIRATION valve open, air through the filter layer “sieve” again, EXPIRATION valve open, decrease resistance. The issue is that it is unclear whether the mechanical switches could fail suddenly while being worn or become trapped in minute particles, so allowing dangerous airborne particles that are not screened through. Consequently, medical masks lack a breathing valve. During this period, the general public is also encouraged to wear KN95/N95 respirator masks or surgical masks without a breathing valve, particularly when the surrounding environment is hostile.
What factors should we consider before donating masks and other materials?
Jin Xiang Yu: When contributing items, it is essential to consult the manufacturer and clearly label the specifics. For donated masks, medical or non-medical varieties, such as anti-pollen masks, anti-haze masks, KN95/N95 masks, medical and surgical masks, etc., should be specified. Due to the relatively low filtration criteria of anti-pollen and anti-smog masks, they are not advised for use by medical personnel, other workers, and journalists on-site during epidemic prevention.