Since the outbreak of the new crown pneumonia epidemic, wearing masks has played an important role in epidemic prevention and control. Recently, rumors such as "wearing a mask can lead to lung nodules" and "residual ethylene oxide on the mask cause cancer" have caused many people

Intern Reporter of Science and Technology Daily Su Jingjing

Since the outbreak of the new crown pneumonia epidemic, wearing masks has played an important role in epidemic prevention and control.

Recently, rumors such as "wearing a mask can cause lung nodules" and "residual ethylene oxide on the mask cause cancer", have caused many people to have doubts and concerns about wearing masks. So, are these views correct?

Source: Visual China

Will wearing a long-term mask cause lung nodules?

"Wearing a mask will cause lung nodules. This question has been compared with the problem of controlling experimental data in medical practice. The data show that long-term wearing of masks has no direct relationship with the occurrence of lung nodules." Qian Kun, deputy chief physician of the Department of Thoracic Surgery at Xuanwu Hospital of Capital Medical University, said in an interview with Science and Technology Daily .

Before the outbreak of the new crown pneumonia epidemic, doctors and nurses in hospitals, operating room anesthesia departments needed to wear masks during work. "For the 20 or 30 years from the start of employment to retirement, medical staff will keep wearing masks at work," said Qian Kun.

According to Qian Kun, data from the hospital's physical examination center shows that as a typical population who has been wearing masks for a long time, the detection rate of lung nodules by medical staff is not higher than that of other non-essential groups in the hospital.

From the perspective of the material of the mask, according to the commonly used medical surgical mask , the mask face is divided into three layers: inner, middle and outer. Among them, the inner and outer layers are polypropylene (PP) nonwoven fabric, and the intermediate layer is polypropylene (PP) meltblown fabric.

Qian Xiaoming, a professor at the School of Textile Science and Engineering, Tianjin University of Technology, said in an interview with Science and Technology Daily that the meltblown cloth used for masks is a microfiber nonwoven material processed from polypropylene polymer material. After this polymer material is processed into a meltblown cloth, it will not produce small molecular substances within the normal use time limit.

Qian Xiaoming pointed out that polypropylene materials may also become powder particles under the action of external forces. However, these powder particles exist in the form of large particles and are difficult to inhaled into the lungs.

For the inner layer of the mask, Qian Kun said that even if the raw material of the inner layer of the mask is PP spunbond fibers break and form 100 microns of hair into the respiratory tract, it will be discharged from multiple human barriers and respiratory self-clearing mechanisms, and will not produce lung nodules.

"The first barrier is the nose hair in the nasal cavity, the second barrier is the respiratory mucus cilia, and the third barrier is phagocytosis. Data shows that only particles with particle sizes less than 10 microns (that is, commonly known as PM10) may cause diseases such as pneumoconiosis. As large particles in life, 100 microns will basically be removed by our mucus cilia system or swallowed by phagocytocytes, and will not form lung nodules." Qian Kun said.

Although the view that "wearing a mask can lead to lung nodules" is not correct, it also reminds us to pay attention to wearing masks in a standardized manner and maintain good hygiene habits. We should use products that meet national standards and change masks regularly.

"From the perspective of hospital infection protection, it is required to change the mask every 4-6 hours." Qian Kun said, "When you find that your friend around you took out a very soft and wrinkle mask from your pocket and furry surface, you should remind him to change the mask in time." Will the residual ethylene oxide on the

mask cause cancer?

"At present, most masks use ethylene oxide, and ethylene oxide is indeed a type of carcinogen released by World Health Organization ." Qian Kun said, "But it is unscientific to talk about toxicity aside. The state stipulates that the residual ethylene oxide after the analysis period of disposable medical masks after leaving the factory cannot exceed 10 micrograms/g, which will not cause harm to the human body."

Picture source: Visual China

Ethylene oxide is a heterocyclic compound, an important petrochemical product and a broad-spectrum sterilizer, which can kill a variety of bacteria, molds and fungi, and is widely used in the fields of washing, dyeing, medicine, pesticides, etc.

Xiao Hailong, director of the Medical Device Inspection Institute of Hangzhou Food and Drug Inspection Institute, once said in an interview that it will take about a month for a mask to be packaged to sterilization of ethylene oxide after 7-14 days of analysis, and then go through factory, warehouse, transportation, sales and other links, and finally reach consumers. Ethylene oxide itself is very easy to volatile and has met national standards when it leaves the factory. Coupled with long-term volatilization, the possibility of residual and endangering health is slim.

Qian Kun said that at this stage, ethylene oxide sterilization is the most common, common and mature sterilization method in the medical device field. Using masks that meet national standards produced by regular manufacturers can effectively protect our health.

What are the causes of lung nodules?

"The newly added lung nodules patients in the past two years have mostly been because they have upgraded the physical examination package , and changed from the original chest x-ray examination to a clearer low-dose spiral CT, or have undergone chest CT examination for other objective reasons, and accidentally found that they have lung nodules. It can be said that the sudden increase in lung nodules patients is an unrelated event in the same period of wearing a mask." Qian Kun said.

pulmonary nodules are a description of focal circular dense shadows with a diameter of ≤3cm in imaging examinations such as chest radiographs or CT.

Qian Kun told reporters that the common components of lung nodules include four types, namely inflammatory nodules, proliferative nodules, benign lung nodules and malignant lung tumors. Clinical data show that more than 90% of lung nodules are benign.

"The external cause of inflammatory nodules is the invasion of bacteria and viruses, and the internal reason is the decline of resistance to ." Qian Kun said, "But the lack of sufficient professional protection in mining, decoration and other work will cause himself to inhale excessive dust in a short period of time and exceed the self-cleaning ability of the lungs. These particulate matter will accumulate in alveolar for a long time and form a chronic inflammatory reaction, eventually forming a proliferative nodule."

Qian Kun said that benign nodules in the lungs are mostly produced under non-specific conditions, while malignant lung tumors are mostly induced by chronic lung diseases or metastasis of malignant tumors in other organs.

Qian Kun recommends that when preventing lung nodules, pay attention to respiratory hygiene, quit smoking, and wear a mask during the season of high incidence of respiratory diseases. At the same time, you should also pay attention to ventilation in the living environment to avoid excessive decoration. Exercise more to enhance cardiopulmonary function. For special occupational groups, occupational protection should be strengthened and occupational physical examinations for toxic and harmful occupations should be regularly participated in occupational physical examinations.

edit: Wang Yu

review: Zhu Li