Can ordinary masks be transformed into N95 masks by tying a knot? Is it really that magical?

[This issue's rumor]: Recently, a video titled "Ordinary mask turns into N95 in seconds" has been widely circulated online. The video description states that "the ordinary wearing method of medical masks can only reduce 84.3% of infectious aerosols, while tying a knot can reduce it by 95.9%, which is equivalent to N95."

Screenshot of the video circulating online

【NetEase Health Assessment】：

It’s a misunderstanding!

【Rumor Identification Points】:

1. Can ordinary masks be transformed into N95 masks by tying a knot? The reprinter made it up!

After verification, the original video was released by the US CDC in April 2021. Based on the problem that medical surgical masks easily leave gaps on the wearer's face, it promoted a way of wearing a mask called Knot & Tuck (tie a knot and then tuck the fabric inward).

The original video did not mention that this way of wearing a mask can improve the protective effectiveness or "turn an ordinary mask into N95 in seconds." The exaggerated statements such as "tying a knot can increase the protective effectiveness by 10 percentage points, equivalent to N95" were all information added by the video reprinter without authorization.

2. Medical masks are better sealed when tied and worn

Following the method demonstrated in the video, the airtightness of ordinary medical surgical masks can indeed be improved, preventing the virus from reaching the respiratory tract directly through the gaps on the left and right sides.

Before launching the popular science propaganda, the US CDC published a related experimental report around February 2021. The report showed that tying a knot and inserting it before wearing it can improve the filtration efficiency.

3. It does not turn into N95 just by tying the knot. There are big differences in all aspects!

The difference between the medical surgical masks and N95 masks we usually use is reflected in many aspects:

In terms of filtration efficiency: N95 masks are one of the nine types of particulate protection masks certified by the National Institute for Occupational Safety and Health. N refers to oil resistance, and 95 means that the filtration efficiency of particles with an aerodynamic diameter of 0.3 microns reaches more than 95%. Medical surgical masks are mainly aimed at bacterial filtration, and the filtration efficiency requirements for saline particles are lower than those of N95 masks.

In terms of material: the filter layers of N95 masks and medical surgical masks are both made of polypropylene meltblown material.

In terms of the number of layers: medical surgical masks are divided into three layers, the outer layer is a water-blocking layer, the middle layer is a filtration layer, and the inner layer is a water-absorbing layer. N95 masks generally have more than 3 layers, usually 4-6 layers. The functions of the outer and inner layers are the same as those of surgical masks, but the middle layer has different numbers of layers for different brands, and its function is filtering.

To sum up, compared with the two, the N95 mask has a higher level of protection.

Medical staff must wear N95 masks when in contact with patients with respiratory infectious diseases; if ordinary people go to medical institutions for medical treatment or accompany others to see a doctor or get medicine, when visiting elderly people, infants or young children or people with underlying diseases, in crowded and poorly ventilated enclosed places such as supermarkets, public transportation, and elevators in public buildings, it is recommended to wear N95 masks if possible to provide yourself with stronger protection.

In daily life, such as engaging in outdoor activities in open areas with good air circulation, or in places with good ventilation, wearing an ordinary medical surgical mask can block most virus-carrying droplets from entering the respiratory tract.

No matter which type of mask you wear, it is very important to wear it correctly. Make sure it covers your mouth and nose and keeps the mask and face fit tightly.