Source: Internet Joint Rumor Refutation Platform
Can blow out the lighter when wearing a mask,
Don’t wear a mask like this,
because it cannot block the virus...
Recently, some "fast methods" to verify whether mask
can block the virus. If
is blown out, can't you prevent viruses?
does not blow out, does it have a barrier effect? Is there any scientific basis for the mask verification method of
?
Before you can easily draw conclusions
Why don’t we follow
professionals to take a look ��
Senior engineers of Shanghai Quality Inspection Institute Yu Hong and Shen Yueming told reporters that there is no necessary connection between the "breathability" of masks and the ability to block viruses. In other words, whether the lighter can be blown out (partial wind blown through the mask) cannot be used to determine whether the mask can block the virus.
The reason why the above "fast method" spreads rapidly on the Internet is related to the fact that many citizens do not know the principle of masks blocking viruses.
Principles 1:1
Masks are mainly used to block aerosols with novel coronavirus particles.
The key safety indicator of masks is [particle filtration efficiency]. Only when this indicator meets the standards can the aerosol be effectively blocked.
Respiratory resistance (also known as ventilation resistance or airflow resistance) refers to the ability of airflow to pass through the mask, is a performance indicator of the mask, and also represents the comfort level of breathing when wearing the mask.
There is no necessary connection between respiratory resistance and filtration efficiency . When the filtration efficiency is qualified, the smaller the respiratory resistance, the more comfortable the wearer feels.
Focus on
"Mask breathable or not" can reflect the quality of the respiratory resistance of masks to a certain extent. There are clear provisions on this in different national standards.
GB 19083-2010 "Technical Requirements for Medical Protective Masks" requires that the airflow resistance shall not exceed 343.2Pa, and the non-medical mask standards shall be standard, such as: T/CNTAC 55-2020 "Civil Protective Masks" shall not exceed 49Pa (adult), and T/CTCA 7-2019 "General Protective Masks" shall not exceed 80Pa.
is visible. In order to ensure the wearer's comfort, mask-related standards have put forward upper limit requirements for respiratory resistance.
The particulate filtration efficiency of masks is a decisive indicator that determines the quality and safety of masks
Particle filtration efficiency refers to the ability of masks to block particulate matter. The higher the filtration efficiency, the better the performance of barrier aerosol. The mask's barrier ability to particles is based on physical barriers on the one hand, and on the other hand, it plays a key role in the electrostatic adsorption of the meltblown cloth in the intermediate layer, and has no necessary connection with respiratory resistance.
"Mask breathability" means that "mask cannot block the virus" is incorrect.
Mask breathability means that the respiratory resistance of the mask is relatively small, but it does not mean that the particulate 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 standards, the new version of the national mandatory standard for particulate protective masks GB 2626-2019 is to reduce exhalation and inhalation resistance and improve user comfort without changing the filtration efficiency.
Supervision departments have taken multiple measures to achieve "zero tolerance" for the quality and safety of epidemic prevention items
Since the outbreak of the new crown pneumonia epidemic in early 2020, Shanghai drug regulatory departments have carried out uninterrupted law enforcement inspections and product quality supervision and random inspections on epidemic prevention items such as medical masks and Shanghai market supervision departments have carried out uninterrupted law enforcement inspections and product quality supervision and random inspections on quality violations such as production and sale of unqualified masks, and achieved "zero tolerance".
Before buying, think about
Choose a suitable mask to deal with different scenarios. The National Health Commission’s "Guidelines for Wearing Masks for Public and Key Occupational Populations" (August 2021 Edition) recommends that in view of the characteristics of the mutant strain of the new coronavirus and the epidemic characteristics of the population at this stage, it is recommended that the public choose disposable medical masks, medical surgical masks or above protective masks.At the same time, Shanghai also provided guidance on "How to take personal protection for urban operation security personnel after the division of the three districts". For the objects of enhanced first-level protection and second-level protection, it is recommended to replace masks with masks of KN95 or N95 or above protection levels.
distinguishes different mask types through standards. Medical masks and non-medical masks implement different national/industry standards (see the figure below), and some non-medical masks implement group standards and enterprise standards.
Don’t trust online videos easily. Some online videos suggest that you judge whether the mask is qualified by blowing the lighter while wearing a mask. This is unscientific and unfounded. The mask material will burn and melt under continuous contact with the open flame. The practice in the video has certain risks. Please do not try it.
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