Experimental environment
■Measurements were carried out in a normal conference room in which the air conditioner was installed in the ceiling.
■The diffusion of micro-sized droplets was visualized when words were uttered with a tracer placed in the mouth.
No masks, no air conditioning
In a RIKEN conference room
First half: raw data
Second half: motion emphasis processing
■The visualization of the diffusion of micro-sized droplets when words were uttered with a tracer in the mouth shows that aerosols spread straight ahead and stay in a cloud-like mass when the air conditioner is not running, and no masks are worn in an environment such as a conference room.
If masks are not worn, exhaled air forms a cloud-like mass that floats towards the person opposite the speaker.
Measurements at a hotel lounge
Air conditioning, no masks
First half: raw data
Second half: motion emphasis processing
■Even if masks are not worn, the air conditioning prevents aerosols from spreading to the seat next to the speaker.
※* Since the specific indoor environment varies depending on the location of the air conditioning, it is desirable to measure each room
Measurements at a hotel lounge
No air conditioning, no masks
First half: raw data
Second half: motion emphasis processing
■Without air conditioning, aerosols can spread far and wide.
■In situations where masks are not worn, such as when eating or drinking, it is necessary to take measures such as diffusing aerosols by operating air conditioners. To minimize this dependence on air conditioning, it is especially important to wear a mask.
※* Since the specific indoor environment varies depending on the location of the air conditioning, it is desirable to measure each room
Micro-sized droplet infection test
■When the infective titer (concentration of the virus) in the aerosol was measured, it was confirmed that the infective titer did not diminish over time.
Evaluation of mask performance by micro-sized droplet penetration
■The following configuration of experimental equipment was used to evaluate mask performance by micro-sized droplet penetration by mask materials.
Masks to be evaluated
■The following configuration of experimental equipment was used to evaluate mask performance by micro-sized droplet penetration by mask materials.
Comparison results of mask performances by material
■It has been confirmed that the infectivity of SARS-CoV-2 in aerosols of 2.5 μ to 5 μ does not decrease nearly as much after 20 minutes. To prevent infection, it is necessary to prevent aerosols from entering the body through the mouth and nose.
■The measurement of aerosol penetration through masks showed that most of masks, including non-woven masks, can prevent the penetration of a great deal of aerosols when worn correctly. This means that infection control measures of "non-infectious" and "non-contagious" can be thoroughly conducted by wearing a mask.
Comparison results of mask performances by material
■Measurement of particles penetrating through the masks shows that almost no particles penetrate through masks other than those made of polyurethane.
■The logarithmic display shows that even ordinary non-woven masks are able to block many aerosols.
