At the end of 2019, the novel coronavirus pneumonia (NCP) from China deeply affects the various sectors of society, and many countries and regions around the world are also affected. The war between humans and the novel coronavirus is testing every aspect, with delayed start of work pressure, out of fear of infection, the International Trade Conference was delayed. To return to normal and orderly work and life, the medical mask which can antiviral is essential.
1 What is the Novel Coronavirus Pneumonia? What are the main routes of transmission?
The novel coronavirus pneumonia – NCP, is an acute respiratory infectious disease caused by the novel coronavirus infection. The main symptoms are fever, fatigue, dry cough and difficulty breathing. Most patients have mild symptoms and a few are critically ill, which can develop into acute respiratory distress syndrome, septic shock, difficulty to correct metabolic acidosis and coagulation dysfunction until death.
At present, there are three ways of transmission of novel coronavirus pneumonia: direct transmission, aerosol transmission, and contact transmission.
Direct transmission refers to the infection caused by the patient’s sneezing, coughing, talking droplets, and the exhaled gas inhaling directly at close quarters.
Aerosol propagation refers to the mixture of droplets in the air to form aerosols that cause infection after inhalation.
Contact transmission refers to the deposition of droplets on the surface of the article, contact the contaminated hand, and then contact the oral cavity, nasal cavity, eyes, and other mucous membranes, resulting in infection.
2 What kinds of masks are there? What kind of mask should we use in our daily life?
Masks are classified into civilian masks and medical masks. A civilian mask is used to filter air into the mouth and nose to prevent harmful gases, odors, and droplets from entering and leaving the wearer’s mouth and nose. Civilian masks mainly divided into cotton mask, non-woven mask, polymer material mask, activated carbon powder filter mask, activated carbon fiber felt pad mask. Medical masks can prevent most of the bacteria, viruses and other pathogens, and WHO recommends that medical personnel use protective masks (N95 masks) against particles to prevent virus infection in the hospital air. Medical masks mainly divided into medical protective masks, medical surgical masks, general medical masks.
There are three commonly used masks on the market: cotton masks, medical surgical masks and medical protective masks (N95 masks), among which medical surgical masks can block 70% of bacteria, N95 masks can block 95% of bacteria, and cotton masks can block only 36% of bacteria. For this novel coronavirus, it is recommended to select the latter two masks for antiviral. If it is to go to public places, do not contact with patients, it is recommended to wear medical surgical masks, do not need excessive N95 Masks, but if contact with patients, not only wear N95 masks but also wear protective clothing, wear goggles.
3 What if the antiviral mask is not enough?
At present, the world is facing a shortage of masks and lack of capacity for mask making machine, we must know how to use the existing masks effectively. For front-line medical personnel and workers, macro-control should be carried out from the national point of view, focusing on N95 masks, protective clothing to protect the epidemic front-line workers. So for the general staff and employees, want to start work, want to go out, what if the medical-surgical masks are not enough?
3.1 Extend the use time of the antiviral mask.
The current international standard is that disposable medical surgical masks can be used for 4 to 8 hours, up to a maximum of 10 hours, depending on the use environment. If it is medical personnel and other public places to work, generally wear 4 hours to change, if ordinary personnel go out, use for a short period of time, can use several times more.
In general, after 8 hours of use of disposable medical surgical mask, PFE (particle filtration efficiency) decreased from 99% to 96%, and respiratory resistance increased from 33Pa to 42Pa. If the mask is used for too long, it will not be able to effectively filter the virus and bacteria, resulting in easy infection. So how should we extend the effective use of disposable masks in this extraordinary period of the epidemic?
3.1.1 Method of preservation of masks
After the mask is used for a short time, if it needs to be used again, it can be hung in a clean, dry and ventilated place or placed in a clean, breathable paper bag. Masks need to be stored separately, avoid contact with each other, and identify mask users.
3.1.2 Air drying by dry heat method
Dry the mask for about 30 minutes using a drying oven, clothes dryer or hairdryer. The temperature should be between 60℃ and 70℃ because if the temperature is too high may cause damage to the filter fiber of the mask, too low temperature cannot effectively sterilize.
3.1.3 Ultraviolet irradiation method
Exposure to the sun, if there are conditions, can also be irradiated with ultraviolet light disinfection, so that the appropriate extension of the time, the specific use time is based on the obvious difficulty of breathing.
3.2 Antiviral masks DIY.
Under the special period of novel coronavirus, in order to protect everyone’s health, to avoid infection with the virus, we need to wear a disposable medical mask to effectively antiviral. However, the epidemic is serious, many people do not have enough masks or cannot buy masks, so if we have to go out, we need to make our own masks. Next, let’s study how to make a mask.
3.2.1 The structure of the mask, the performance of each component
When people are talking, coughing, sneezing and spitting, they spew out droplets, which can carry a variety of pathogens. Medical masks can effectively prevent infection, which is determined by its structure and material.
Medical masks are generally divided into three layers, three layers of non-woven fabric with different structures and functions. The outer layer is a waterproof layer to block the droplets; the second layer is a filter layer that filters the bacteria and droplets brought in by the air stream, and the third layer is a moisture-absorbing layer that absorbs the exhaled moisture. There are also two auxiliary components, a metal strip and a pair of ears hanging, the metal strip for the nose bridge so that the mask and face form a closed space.
The mask must meet certain standards before it goes out of the factory, the common standards are EN 14683, EN 149, ASTM F2100, YY 0469 and so on, and there are many test items. Please refer to this article for the relevant contents of the standard and test: Quality Detection and Specification for Use of Medical Masks or N95 Masks – for the Novel Coronavirus。
For this novel coronavirus, if we make-self masks, there is no need to verify each test item, but it is necessary to know several key performances. The anti-foam performance of the outer layer of the mask, the performance of the filter virus and particulate matter in the middle layer of the mask, the moisture absorption performance of the inner layer of the mask, and the respiratory comfort of the whole mask, refer to the relevant standards, we give the following suggestions: table 3.2.1
|BFE: The middle layer
outer layer, anti-fly foam
|Just feel less
difficult to breathe
3.2.2 How to choose materials and how to make a mask?
The non-woven materials we can contact in daily life are: cotton cloth, rag, wipe cloth, wet face towel, magic towel, pilose towel, beauty products, sanitary napkin and disposable sanitary cloth, as well as some common packaging bags, cling film and so on. If we want to make-self masks, we must test the related performance of these common materials according to Table 3.2.1 and select the appropriate materials. Relevant test instruments are as follows:
Test the waterproof performance of the material with impact penetration tester, select the material with good performance to anti-fly foam. Test the flame resistance of the material with 45 degree flammability tester to determine the safety. Test the air permeability of the material with medical mask differential pressure tester to find out the material with good respiratory performance. After testing the non-woven fabric with medical face mask testing instruments, we recommend using the following materials to make-self masks: common cotton cloth for the outer layer, felt or towel for the middle layer (choose polypropylene fiber material as far as possible), and medical gauze for the inner layer.
Steps of make-self mask:
Step 1: Cut the prepared material into a suitable shape, probably: 18cm*9cm for adults, 15cm*9cm for children.
Step 2: Align, in the order of inside, middle and outside.
Step 3: Fold the upper and lower sides into the inside, the upper hem can be added to the metal strip, leaving enough gap in the middle to penetrate the rope.
Step 4: Sewing, the make-self mask is finished.
Note: Use the make-self mask only if you cannot a buy medical mask or N95 mask and have to go out. Replace it within four hours. Do not add anything else to it. If someone around you can’t buy a mask, forward the article to them. If you want to buy a reliable mask, look at this: www.testextextile.com/product/medical-face-mask