"Science" rumors

Zhang Hang

Myth 1

New crown virus can be transmitted through aerosols,

So you ca n’t open the window for ventilation

Myth: New crown virus can be transmitted through aerosols, so you can no longer open the window for ventilation, otherwise it will be easily infected.

Truth: According to the "New Coronavirus Pneumonia Diagnosis and Treatment Program (Sixth Trial Version)", the virus is transmitted via "respiratory droplets and close contact transmission is the main route of transmission. Long-term exposure to high concentrations of aerosols in a relatively closed environment The possibility of transmission through aerosols. "

Aerosols are very tiny droplets or solid particles that can be suspended in the air for a long time. Microparticles containing biological substances such as microorganisms or biological macromolecules are called bioaerosols, and those containing microorganisms are called microbial aerosols.

However, aerosol transmission occurs only in specific, high-concentration environments. First, aerosols are continuously diluted by the flowing air. The lower the concentration of virus-containing aerosols in the air, the lower the probability of infection. Research on SARS that year found that in the ward, if the windows were closed tightly, the virus concentration in the air would increase, and in this environment, medical staff would be relatively susceptible to SARS coronavirus. In contrast, if the windows are opened for natural ventilation, the air flow and air exchange rate in the ward can be very high, which can greatly reduce the concentration of viruses (aerosols) in the air, and reduce the possibility of infection of the medical staff.

Opening windows frequently, especially in public places, such as offices and medical institutions, can reduce the concentration of viruses (aerosols) that may be in the air, and reduce the risk of infection through inhalation through the air.

Myth 2

Smoking prevents new crown virus infection

Myth: Tobacco particles are nano-sized and can evenly cover the surface of lung cells, forming a barrier to block the virus from the human body. Therefore, smoking can reduce neocoronavirus infection.

Truth: This statement is wrong.

First, there are two kinds of components produced by the combustion of tobacco: one part is gas, such as carbon monoxide, which accounts for more than 90%; the other part is solid particles, such as nicotine and tar particles. According to the Chinese Center for Disease Control and Prevention, these particles are between 1 micron and 2.5 microns in size, not nanoscale. The size of different viruses varies widely, but they are all nanoscale. 1 micron is equal to 1000 nanometers. Counting on tobacco particles to block the virus is roughly equivalent to filtering water with gauze, which is not realistic.

Secondly, tobacco can not only help the respiratory tract resist foreign enemies, but also cause damage to the respiratory tract. Studies show that tobacco contains more than 7,000 chemicals, including dozens of carcinogens. They can interfere with the normal functioning of the lungs, disrupt the lung's defense system, and cause diseases such as chronic obstructive pulmonary disease, lung cancer, emphysema, and chronic bronchitis.

Studies have also shown that smoking increases the risk of getting flu. A 16-year follow-up study of 300,000 veterans in the United States has shown that smokers have a much higher death rate from flu than non-smokers. In other words, smoking not only increases the probability of respiratory virus infection, but also worsens the consequences of the infection.

Rumor 3

You can use steaming, boiling, microwave heating,

Spray alcohol disinfection masks

Myths: Steaming, boiling, 75% ethanol, UV, microwave heating and other methods can sterilize the mask.

The truth: The filter layer of the mask is mainly composed of polypropylene meltblown microfiber, which is very thin, not resistant to high temperatures, and shrinks and deforms when the temperature is higher than 80 ° C, causing structural damage and reducing protective effects. The entry of water will also cause the charge in the filter layer to disappear quickly, leading to a significant reduction in the filtering effect.

The outer surfaces of medical surgical masks and medical N95 masks are water-repellent, making it difficult for alcohol, blood, saliva, etc. to penetrate. Therefore, it is difficult to disinfect the surface with alcohol. At the same time, alcohol will damage the waterproof structure of the outer layer of the mask, and the absorption of blood and saliva by the mask material treated with alcohol will increase, which will accelerate the failure of the filter layer of the mask.

Polypropylene meltblown material is a thermoplastic polymer material that is very sensitive to ultraviolet rays. After receiving ultraviolet rays, the structure will be destroyed, that is, oxidative degradation, and the filtration performance will be greatly reduced.

Microwave heating will also destroy the internal structure of the mask. At the same time, if the microwave is used to treat medical waste, it will not be able to continue to heat food.

(Beijing Association of Science and Technology, Beijing Association of Science and Technology Journalists and Editors)