“Demonstration experiment to visualize the scattering situation of the droplets madeby blowing darts was carried out.”「The Droplets do not scatter by blowing darts?!」
Demonstration Experiment carried out by: Japan Sport Wellness Fukiya Association
Experiment Collaborator: Shin Nippon Air Technologies Co., Ltd.
Supervised by: Mr. Hiroyuki IMAI, Doctor of Medicine
In order to play Sport Wellness Fukiya safely under executing the infection control
measures for COVID-19, Japan Sport Wellness Fukiya Association carried out thedemonstration experiment of visualizing the scattering reality of the droplets made byblowing darts. To confirm the safety of playing Sport Wellness Fukiya and to know thecorrect countermeasures are the purposes of carrying out this demonstration experiment.
Outline of ExperimentThree players blew darts for several experiments in the clean room of Shin Nippon Air
Technologies, who is the pioneer of Clean Room in Japan, and observed scatteringsituation of the droplets made by blowing darts.
 Image of clean room

 Image of targets wrapped by industrial plastic wrap (because we observed a lot ofdust came out from the target when darts stuck in the target)1

“What we understood from the demonstration experiment”
Dr. Imai’s comments are as follows: We understand that there are almost no droplets scattered from the muzzle of blowing
pipe. The droplets out of the muzzle of blowing pipe are less than the droplets madeby the normal conversation without mask and we could say that there is almost nopossibility of spreading droplets infection by Sport Wellness Fukiya.
 Main infection routes of COVID-19 are known “Droplets Infection” and“Contagion”, but they say recently that there may be some possibility of “AirborneInfection”. Thus, it is advisable that we should keep normal cautions, such as,
frequent changing of air, having mask etc.
 There are some images showing that something dropped from the end of the dart
when sticking in the target. I cannot say completely that these are the droplets, butthere may be slight possibility that the droplets are conveyed to the target by the dart.
Therefore, it is necessary to wipe (disinfect) the surface of target.
Blowing without dart
After cleaning the inside of blowing pipe, players blew without dart. At the first blow, wecould see slight particle, however there were no particle from the second blow andonwards. We judged these were not the droplets.
 Image of the 1st blow Image of the 2nd blow2

How much droplets leak from the mouth, when blowing darts?
In case players held the blowing pipe deeply in their mouth, we could not see any droplet
scattered from the mouth of all three players. Even if they blew with the corner of themouth opening, we could not see any droplet scattered from the mouth. However, in casesome player held the blowing pipe shallowly, which is out of basic motions, there might
be a possibility that a very few droplet leak from the mouth. Thus it is important that
players should hold the blowing pipe deeply and tightly in the mouth as prescribed in thebasic motions of Sport Wellness Fukiya.
Evaluation by Shin Nippon Air Technologies:“We could see almost no particles when blowing darts.”
 Image of holding the blowing pipe deeply Image of holding the blowing pipe shallowly

How much droplets leak from the muzzle of blowing pipe when darts coming out?
At the first blow just after cleaning inside of the blowing pipe by cloth, we could confirm
some particles came out from the muzzle of the blowing pipe together with the dart.
However, the particles decreased from the second blow onward and we could not see any
particles at the fifth blow. From this result, we believed that these particles were not the3droplet but the dust or fiber attached inside of the blowing pipe.
Evaluation by Shin Nippon Air Technologies:“We could see some particles at the first blow of all three players. But, particles weregetting fewer and no particles were found at the fifth blow of all three players.”
 Image of the 1st blow Image of the 2nd blow Image of the 5th blow4How is the condition of droplets at the surface of target when the dart sticking in?
 Comparison of droplet of the 1st dart with the 2nd dart (5m distance):
Floating matter confirmed at the 1st blow was getting extremely fewer at the 2nd blow andonward. Thus, it is considered that fibers of the cleaning cloth came out together with thedart at the 1st blow.
 Image of the 1st dart

 Image of the 2nd dart

 Comparison of the surface by blowing from 5m distance with 8m distance:
At the moment of the dart stuck in the target, we confirmed that something dropped fromend of the dart, but it dropped immediately and did not scatter. We could not see any
difference due to the blowing difference. It is advisable that we had better wipe
(disinfect) the target surface because we usually touch the target when pulling out darts.
Evaluation by Shin Nippon Air Technologies:“We could not see any outstanding difference due to the blowing distance. We could
realize the tendency that particles (we cannot completely say that these are droplets) of
the first half were more than those of the second half.”5 Image from 5m distance Image from 8m distance Due to high-illumination exposure on the target, images showed that darts expanded
because of halation.
How is the condition of the space at about 2m apart from the muzzle of the blowing
pipe?
From the images of the darts at the space of about 2m from the muzzle of the blowing
pipe, we could see only a few floating material. We cannot say completely that this must
be droplets.
 Images at the space of 2m

6 Due to using three lightings, images showed a dart as three rings because of halation
after image.
Differences of the particles out of the muzzle of the blowing pipes due to thediameter of the darts:
We could see more particles when blowing 13.00mm diameter dart than blowing
12.85mm diameter dart. It is considered that in case we blow a dart with a bit bigger
diameter than normally used, we may blow stronger and the dart may be rubbed against
inside of the blowing pipe which causes more particles. We would like to recommend
using a bit smaller diameter darts.
 Image of blowing 12.85mm diameter dart

 Image of blowing 13.00mm diameter dart

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Vocalization/Wearing mask
Many droplets were confirmed by the conversation without wearing mask which aremuch more than the particles out of muzzle of the blowing pipe and looks scattered. We
would never blow darts towards persons, risk of sport Wellness Fukiya infecting
COVID-19 is much less than that of normal conversation without mask. As the efficiencyof wearing mask is very high, we strongly suggest wearing mask except when we blowdarts.
 Image of vocalization without wearing mask

 Image of vocalization with wearing mask

Comments from Mr. Takashi ARAI, Doctor of Medicine, Advisor of Japan Sport
Wellness Fukiya Association:
By this demonstration experiment, it is confirmed that droplets made by blowing darts aremuch less than those made by the normal conversation without mask. I would like tokeep myself in good health by continuing Sport Wellness Fukiya with the correct
countermeasures for viral infection. I appreciate Dr. Imai’s supervising this valuable
demonstration experiment.
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Overall Summary
From the result of this demonstration experiment:① No droplets came out from the mouth. However, in case holding the blowing pipe
shallowly, which is out of the basic motions, a few droplets were found. It is
important for all of us to be faithful to the basic motions.
② A few particles came out from the muzzle of the blowing pipe together with thedart, but did not scatter.
③ We could not confirm that particles reached the target even for 5m blowing
distance.
④ From the above ① through ③, we could say that droplets did not come out by
blowing darts. Even if we consider that all particles are droplets, they are much lessthan those made by normal conversation.
The most important matters under the current new way of life with COVID-19:
 Participants must keep health care regularly, such as measuring temperature; Checking health condition and measuring temperature of participants;
 Keeping habits of preventing infection, such as disinfection of hands and fingers,wearing mask, avoiding close contact and crowd together; and Changing air of the venue every 20 to 30 minutes.
It is really important that we should keep the above and follow “The suggestion of Dr.
Imai” (announced in May 2020).

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