In order to test the blocking effect of masks on viruses
Have you tried wearing a mask to blow air? Put out the lighter?
Blowing out is a barrier?
Blowing out can’t prevent virus?
before jumping to conclusions< /p>
Let’s take a look with the professionals
One
Principle Learn a lesson
1. Masks are mainly used to block Aerosol with novel coronavirus particles.
2. Key Safety Indicators of masks It is the [particulate matter filtration efficiency]. Only when this indicator reaches the standard, can the aerosol be effectively blocked.
3. Breathing resistance (also known as ventilation resistance or airflow resistance) refers to the airflow through the mask The ability of the mask is the performance index of the mask, and it also represents the comfort of breathing when wearing the mask.
4.There is no necessary relationship between breathing resistance and filtration efficiency , under the condition of qualified filtration efficiency, the smaller the breathing resistance, the more comfortable the wearer feels.
Two
Highlights
1.
“Is the mask breathable or not? “To a certain extent, it can reflect the quality of the breathing resistance of the mask, which is clearly stipulated in different national standards.
GB 19083-2010 “Technical Requirements for Medical Protective Masks” requires airflow The resistance does not exceed 343.2Pa, non-medical mask standards, such as: T/CNTAC 55-2020 “Civilian Protective Mask” requires no more than 49Pa (adult), T/CTCA 7-2019 “General Protective Mask” requires no more than 80Pa.
It can be seen that in order to ensure the comfort of the wearer, the relevant standards for masks put forward the breathing resistance. cap requirements.
2.
The particle filtration efficiency of the mask isDecisive indicators for the quality and safety of masks
Particle filtration efficiency refers to the barrier The ability of particulate matter, the higher the filtration efficiency, the better the aerosol barrier performance. The barrier ability of the mask to particulate matterOn the one hand, it depends on the physical barrier, on the other hand, the electrostatic adsorption of the meltblown cloth in the middle layer plays a key role. , not necessarily related to respiratory resistance.
3 .
“The mask is breathable” means “the mask does not block the virus” is incorrect
The breathability of the mask indicates that the breathing resistance of the mask is relatively small, but it does not mean that the particle filtration efficiency of the mask must not meet the requirements. Under the continuous supervision and orderly promotion of government departments, enterprises have gradually adopted higher national standards. Compared with the old standard GB 2626-2019, the new version of the national mandatory standard for particulate protective masks, the main improvement is that the filter does not change. On the premise of efficiency, the resistance of exhalation and inhalation is reduced to improve user comfort.
4.
The regulatory authorities take multiple measures to achieve “zero tolerance” for the quality and safety of epidemic prevention items
Since the outbreak of COVID-19 in the city in early 2020, the city’s drug regulatory authorities have carried out uninterrupted law enforcement inspections and product quality supervision on anti-epidemic supplies such as medical masks, and the city’s market regulatory authorities on non-medical masks and other anti-epidemic supplies Follow up and spot checks, maintain a high-pressure situation for quality violations such as the production and sale of substandard masks, and achieve “zero tolerance”.
Three
Think Before You Buy
1.
< strong>Choose suitable masks for different scenarios.
National Health Commission’s “Guidelines for Wearing Masks for the Public and Key Occupational Groups” (August 2021 Edition) recommends that for the current stage of the new coronavirus Due to the characteristics of the mutant strains and the epidemic characteristics of the population, it is recommended that the public use disposable medical masks, medical surgical masks or masks of above protection level. At the same time, the city has also provided guidance on “how to protect the city’s operation support personnel after the division of the three districts”. For the objects of enhanced primary protection and secondary protection, it is recommended to replace the masks with KN95 or N95 and above protection level masks.
2.
Identify different mask types by criteria.
Medical masks and non-medical masks implement different national/industry standards (see the figure below), and some non-medical masks implement group standards and corporate standards.
3.
Don’t trust online video.
Some online videos suggest wearing a mask to blow air on a lighter to determine whether the mask is qualified or not. This is unscientific and has no basis. The mask material will burn and melt under continuous contact with an open flame. , The practice in the video has certain risks, please citizens and friends not to try it.
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Data: Shanghai Market Supervision
Editor: Li Bingqian span>
*Reprint please indicate the source from “Shanghai Changning”