<Anchor> When
I go to places where many people gather indoors, such as a restaurant or a bar, I am worried about corona.
Sometimes I wonder if opening the door and ventilating would help, but we found out how people's saliva floats indoors and how it changes when ventilated.
Reporter Shin Seung-yi and Choi Jae-young reporters one after another.
<Reporter> In the
Corona era, indoor spaces are always burdensome.
A restaurant district in Yeouido, Seoul.
There are still quite a few places that are closed and open.
[Coffee shop staff: (How do you ventilate, here?) I only do it three times a day.
If we hit the headwind, what we have piled up will fly away.]
[Won Ju-hye/Seoul Yeongdeungpo-gu: I'm still reluctant.
I'm not sure yet.
Ventilation doesn't mean I can see it directly with my own eyes...]
Ventilation, how often and what to do.
I did experiments with researchers from domestic universities.
First, researchers at Sejong University analyzed the movement of 2,200 saliva droplets that occur when coughing through computer simulation.
With mechanical ventilation, 6 times per hour, i.e., 6 times the volume of outside air in an hour.
The air conditioner is not turned on.
The salivary droplets travel in the air stream toward the exhaust, some of them exiting, but the rest of them spreading back into the room.
This time, I turned on the ceiling air conditioner and experimented with the same ventilation conditions.
As soon as you cough, the salivary droplets are sucked into the air conditioner and quickly spread in all directions.
This time there are more particles being released into the exhaust vent.
As a result of the experiment, half of the droplets disappeared, but it took 17 minutes when the air conditioner was turned on and 6 minutes when the air conditioner was turned on.
After 30 minutes, if the air conditioner was turned on while ventilating, the amount of saliva dropped to 20%.
[Sung Min-ki/Sejong University Professor of Architectural Engineering: As the air conditioner circulates indoor air, it diffuses (particles) a little more quickly, so it has such an effect that it is quickly discharged through the exhaust port.]
But if the ventilation volume is reduced to 0.5 times per hour Varies.
If only the air conditioner is turned on in a poorly ventilated condition, little saliva is discharged and it spreads to every corner of the room, making it more dangerous.
[Sung Min-ki/Professor of Architectural Engineering, Sejong University: If the number of ventilation is small, it can be said that even large particles that slowly diffuse indoors or sink to the ground have a bad effect of rapidly spreading indoors.]
Therefore, in a dense room, as much as possible. It is recommended to use the air conditioner's cooling or blowing functions, fans, etc., with a high ventilation level and as far away from people as possible.
It would be nice if there was a mechanical ventilation device that could control the air volume, but I found out how to ventilate in a building that doesn't, through another experiment.
<Reporter Choi Jae-young> This
is a coffee shop located in Suwon, Gyeonggi-do.
All doors and windows were closed and laboratory smoke was smoked.
The air is stagnant and the smoke rises straight up only.
This time, both doors facing each other were wide open.
Smoke flows through the wind.
When both doors, which are 18% of the wall area, were opened, the ventilation volume increased to more than 11 times per hour.
In one hour, air is circulating at least 11 times the volume of the room.
Even when only one window and door are opened, the ventilation volume is recorded '7 times per hour', and when the fan is operated together, it is about '10 times per hour', similar to the case of opening both doors.
Just by leaving the window open, you can see the effect equal to the ventilation standard of the infectious ward.
As the amount of natural ventilation changes from moment to moment, it is better to use auxiliary devices such as an electric fan, but a restaurant kitchen fan and toilet exhaust fan are also helpful.
[Song Doo-sam/Professor, Sungkyunkwan University, Department of Civil and Environmental Engineering: Make these fans more auxiliary so that the air can always escape (should).
The reason that the air escapes is that the amount of fresh outside air comes in.]
However, in the case of late autumn or winter, when the temperature difference between indoors and outdoors becomes large
due
to cold weather, sufficient ventilation can increase the burden of electricity bills. It seems necessary.
(Video coverage: Lee Byeong-ju·Lee Yong-han, video editing: Lee So-young, CG: Hong Seong-yong, Choi Jae-young, Kim Min-ah, Lee Ye-jeong, Seong Jae-eun, VJ: Jeong Young-sam, Jeong Han-wook, Kim Choa)