Over the past two days, after exposure to transmission and fecal transmission, aerosol transmission — a new way to spread the new coronavirus – began to be focused. “Air poison can float a few kilometers away” “open window ventilation can also induce poison into the room” … What is the aerosol of “God”, which is passed down by netizens? Is aerosol propagation really so dangerous?
Air is poisoned, is it a hole to the wind?
Since the outbreak of new coronary pneumonia, with the scientific community’s understanding of the virus gradually deepened, the transmission of the virus has been recognized by the public.
From close-to-the-reach droplets, to invisible but “touched” contact transmission, from “disease from mouth in” manure transmission, to air-borne aerosol transmission … Along with the promotion of scientific research, the same increase is also the difficulty factor of prevention and control and the public panic.
Recently, Ningbo disclosed a new case of coronavirus infection, infected with the confirmed patient only close to 15 seconds to be infected. This has brought renewed concern about the way the new coronavirus is spread.
February 8, Shanghai epidemic prevention and control work leadership group press conference revealed that there are health and epidemic prevention experts pointed out that the current can be determined the transmission of new coronary pneumonia mainly for direct transmission, aerosol transmission and contact transmission.
News out, on the network immediately became a hot search topic, “virus in the air can float out of the air for several miles” “open window ventilation will also be in the middle of the trick” “air transmission and how to prevent” …
Additional takeaway peace of mind cards are attached to the delivery and information about the contact of the meal. China News Agency reporter Jing Jing
What is the aerosol that makes people “shiver”?
The so-called aerosol, academically speaking, refers to a gaseous dispersion system consisting of solid or liquid particles suspended in a gas eous medium. In layman’s terms, in order to distinguish it from clean air, dusty or polluting gases are often used to refer to aerosols.
In fact, aerosols can be produced naturally, such as clouds, fogs, hazes, dust floating in the air, are aerosols.
Aerosols can also be formed manually, such as sneezing, coughing droplets, large droplets quickly fall to the ground or surface of objects, tiny droplets can be suspended in the air for a period of time, the latter belongs to aerosols.
According to Feng Zhaoxuan, a researcher in the Infectious Diseases Department of the China Center for Disease Control and Prevention, the aerosol transmission of the virus refers to the loss of moisture in the air suspension process and the remaining proteins and pathogens composed of the nucleus, the formation of a droplet nucleus, can be floated into the distance through the form of aerosols, resulting in long-distance transmission.
Can aerosols actually spread the new coronavirus?
Although the relevant experts in Shanghai confirmed that there are channels for aerosol transmission, but whether it is the National Health and Reform Commission’s diagnosis and treatment program, or the China Center for Disease Control and Prevention experts, show that the route of aerosol transmission has yet to be clarified.
– National Health and Care Commission: yet to be clarified
On February 4th, the National Health and Reform Commission issued the “New Coronary Virus Infection Pneumonia Treatment Program (Trial Fifth Edition)” shows that the main routes of transmission through respiratory droplets and contact, aerosols and digestive tract and other routes of transmission have yet to be clarified.
Photo Source: Pneumonia Treatment Programme for New Coronary Virus Infection (Trial 5th Edition)
On February 8th, when experts in Shanghai said that the identifiable routes of transmission of the virus included aerosol transmission, the revised version of the fifth edition of the diagnosis and treatment program issued by the National Health and Reform Commission was reiterated that the expression “the routes of transmission such as aerosols and digestive tracts have yet to be clarified”.
– Cdc experts in China: Transmission may occur under special conditions
In addition, in the National Health and Health Commission website “You ask me to answer” column released on the 8th, China’s CDC infectious diseases researcher Feng Zhaosaid said that at present, the main transmission of the new coronavirus or respiratory droplets spread and contact transmission, aerosols and feces – mouth and other transmission routes have yet to be further clarified. Epidemiological investigations have shown that many cases can be traced to close and close contact with confirmed cases.
He says the new coronavirus can be transmitted through respiratory droplets. The droplets travel very short and do not float in the air for long. Aerosol propagation may occur under certain special conditions, such as when performing specialized medical operations such as clinical trachea intubation.
If in the normal clinical care, general working life conditions, take the correct wearing mask droplet transmission protection measures, is sufficient to protect the general public without infection.
“Yet to be clear” aerosol transmission how to prevent?
– Which specific places need to pay special attention to aerosol propagation?
Professor of Environmental Science and Engineering College and expert of biological aerosols at Peking University told the media, for example, in the automobile and office environment, there is not enough ventilation, but also relatively small, especially extreme environment is in the car, aerosol transmission and droplet stoma transmission should be placed in the same important position to consider.
Classrooms, he says, are also an environment to consider. For example, in a classroom there are two or three patients, after a period of period of viral aerosol accumulation, without timely ventilation, the chances of aerosol transmission of infection is very high. The ventilation of the subway, aircraft and high-speed trains is relatively good, and the carriages and cabins are constantly exchanging air with the outside world.
If there are patients, the likelihood of other healthy people infected through aerosols is related to the distance or direction of the air flow with the patient, he said. For example, the farther away from the patient, nor the direction of the air flow, the probability of infection is lower.
He said that inhalation of the virus will not necessarily be infected, depending on the dose and activity of inhalation, low dose and low live virus, infection may not occur, different virus situation is not the same.
– What is the probability that aerosol stoics can infect healthy people in open atmospheric space?
Qian Hua, a professor at The University of Southeast’s School of Energy and Environment, said the risk of long-range infection salutation was much lower than at close range. Aerosol transmission over long distances, the risk of infection is not only associated with individual resistance, but also related to viral aerosol concentration, virus activity in aerosol and duration of exposure.
Qian Hua said that people exhale with viral aerosols, first in the form of droplets out. Small droplets will quickly evaporate dry to form a droplet nucleus, if the virus in the process of evaporation dry droplets also have activity, these with the virus droplet nucleus is easy to feel inhaled, or contact with the eye conjunctiva, nasal mucous membrane, mouth mucous membrane may form an infection. Ventilation can dilute the viral aerosol and reduce the risk of transmission.
To flourish also analysis, patients discharge of viral aerosols in the open environment rapid dilution, concentration significantly reduced, activity is affected, the probability of inhalation and dose are greatly reduced. When there are no close-up droplets nearby, healthy people are less likely to be infected than in traffic accidents.
– How should the public prevent indoor aerosol infection?
Qian Hua, a professor at Southeast University’s School of Energy and Environment, said:
First, the natural ventilation is very large, open the window, the virus dilution to a certain extent, the risk is very low. Ventilation effect with the day’s wind speed direction, opening size and indoor and outdoor temperature difference, now the season ventilation should be very large, the best conditions best multi-frequency window opening, such as every two hours open the window for 10 minutes.
Home has a new fan open fan, there is a purifier opener, purifier will filter aerosols, including viral aerosols, while not to touch the filter.
Second, the bathroom also should pay attention.
Now there are studies that show that feces also carry the virus, when flushing the toilet, cover the toilet lid and flush. Each floor leak water, water seal well, to prevent the downstairs aerosol son.
Third, the elevator room ventilation is very poor, but also small space, must wear a mask, careful touch. In addition, wash your hands frequently, scrub, and separate your distance from others.