Toward the world without
lockdown
An engineering approach for
fighting COVID-19
Low-cost
and high-performance Powered Air-Purifying Respirator (PAPR) as aｎ engineering alternative to
lockdown.
by NPO e-JIKEI Network
Promotion Institute
[Announcement]
An International Project for Saving the World from
COVID-19 has just been launched with the Japanese government funding!
International Research Collaboration Project
Development of Low-Cost Powered Air-Purifying Respirators
(PAPRs) and Operational Tests in Hospitals in Cebu City, Philippines
http://www.e-jikei.org/site/KAKENHI_FosteringJointResearchB_E.htm
Call for companies for mass production! Contact us if you
are interested in this project.
A simple engineering
way of fighting COVID-19 is proposed.
First, the
possibility of mass production of an inexpensive helmet-type mask, whose
shielding rate against virus invasion is almost 100%, is shown.
Second, the
possibility of obtaining a pseudo herd immunity by means of the numerical
control of the wearing ratio of the helmet-type masks is shown.
Introduction
The world is in an intermittent
lockdown state due to COVID-19 [1,2,3]. 'Herd immunity' is normally obtained
either through vaccination or immunity developed through previous infection.
WHO supports achieving 'herd immunity' through vaccination, not by allowing
COVID-19 to spread through any segment of the population, as this would result
in unnecessary cases and deaths [4].
We propose an alternative engineering
way to achieve 'pseudo herd immunity' through the mass spread of the
almost-perfect masks. This proposal is based on the following 3 simple
ideas/hypothesis.
[a] Mass
production of helmet-type masks, which shield viruses 100%, is easy with the
modern technology.
[b] If
every person wears the helmet-type mask all the time, anyone cannot be newly
infected. And all the airborne infectious diseases, including COVID-19, will be
shut down promptly.
[c]
Considered in the same way as herd immunity, the mask wearing rate, which is
required to converge the infection, is not necessarily 100%.
This research is the improved one
from the previous researches by us [5,6] based on the inventions made by us
[7,8].
Prototype of the helmet-type almost-perfect
mask
Figure 1 shows a helmet-type mask
(total mass: 664g, operational time: 8 hours, total cost of parts: 200USD)
developed using commercially available parts. If it is mass produced, the price
is estimated to be 100USD or less.
The features of the developed prototype are
the following two points.
[a]
Positive internal pressure
The pump
power is controlled so that the flow rate is 100 L/min or larger, the carbon
dioxide concentration is 2000 ppm or less and the internal pressure is 50 Pa or
higher than the outside.
[b]
Filtered air intake
Pumps make
all the intake air filtered with a non-woven filter (HEPA H13 standard, 99.97%
adsorption of particles up to 0.3 μm). Natural exhaust filtered with a
non-woven filter (95% adsorption of particles around 0.1-0.3 μm) is realized
due to the higher internal pressure.
The particles in a bio-aerosol are
generally 0.3 to 100 μm in diameter [9], therefore, the adsorption rate of
particles up to 0.3 μm can be considered as the virus shielding rate. Since the
air invasion from the outside cannot occur due to the positive internal
pressure, the aerosol/virus shielding rate of intake air Sr,in is
estimated to be approximately 1.00 (100%). The virus leakage to the outside
mainly depends on the air tightness of the neck seal, and it is estimated to be
5% or less. Therefore, the aerosol/virus shielding rate of exhaust air Sr,out
is estimated to be approximately 0.90 (90%) or higher.
(a) Photo of the mask
(b) Schematic of the mask
Fig. 1. The prototype of the helmet-type mask (with Sr,in =1.0 and Sr,out =0.9 )
Infection control by means of the helmet-type masks
If all the people wears this mask
(Sr,in
=1.0) all the time, no people can become newly infected and the spread of
infection will be shut down immediately. However, with the concept of held
immunity, not necessarily 100% people should wear the mask (Sr,in
=1.0) all the time to converge the spread of infection, as discussed below.
A susceptible person, who wears a
mask that perfectly blocks the entry of the virus (Sr,in =1.0),
cannot become infected and then cannot infect others just like an immunized person.
If the ratio Wr of all the people in a society wear the masks (Sr,in
=1) all the time, that means, the ratio Wr of all the susceptible
people wear the masks and they cannot be infected. Then, the effective
reproduction number Rt of COVID-19 of the society is reduced to the
modified effective reproduction number Rtm as follows,
Rtm = (1- Wr) Rt
(1).
Wr = 1 – Rtm/Rt (2).
By estimating the current
effective reproduction number Rt and setting the target
of the modified effective reproduction number Rtm, the
required mask wearing ratio Wr can be calculated
using the equation (2).
Table 1. Proposed social status for fighting
COVID-19
In the above discussion, the
condition in which ratio Wr of all the susceptible
persons wear the helmet-type masks all the time, can be replaced by the
condition that all the susceptible persons wear the helmet-type masks at the
ratio Wr of all the interpersonal physical contacts.
When lockdown is required due to
the spread of infection, the government can take the following alternatives in
lieu of lockdown as shown in Table 1.
[a] Every
person is required to wear the helmet-type masks (Sr,in =1) when
going out.
[b] The
wearing rate Wr, which each person should follow, is shown.
By developing and introducing a
system for measuring and managing the wearing rate of each individual, a
society, in which each person is officially encouraged to make the
interpersonal contact without the mask within the ratio of (1- Wr)
for maintaining the health of the society, could be created.
As for evaluating the effective
amount of the interpersonal physical contacts, various indicators can be
considered, such as [a] the ratio of the time spent wearing the mask to the
time spent going out, and [b] the ratio of the number of people contacted with
the mask to the total number of people contacted. It is necessary to examine the
validity and implementability of the indicators from the viewpoints of control
of the infection spread.
Figure 2 shows the wearing rate Wr
of the mask (Sr,in = 1), which is required to realize the
modified effective reproduction number Rtm =0.5 for the society
with the current estimated value of the effective reproduction number Rt.
Figure 2 Wearing rate Wr required to realize Rtm=0.5
(using the helmet-type mask with Sr,in=1.0)
For an example, in order to
realize Rtm = 0.5 and halve the number of infected people every
infection period in a society under almost the worst infection situation of Rt
= 5.0, the helmet-type mask with 100% intake shielding rate (Sr,in
= 1.0) should be worn by 90% (Wr = 0.9) of all the
members of the society at all the time. Alternatively, all the members of the
society should wear the masks in 90% of all the interpersonal contacts.
Discussions
Considering that infectious
people, including asymptomatic infectious people, wear the helmet-type masks
with a higher exhaust shielding rate Sr,out than usual face
masks, the modified effective reproduction number Rtm is
considered to be lower than that derived from the equation (1).
If this proposal is taken by the
society, then, the comfort, convenience, functionality and design of the helmet-type
masks will be rapidly and significantly improved by the efforts of companies
and governments.
As for “air” not like “water”,
modern people, still like primitive people, breathe “natural air”. With the
advent of very-comfortable and almost-perfect helmet-type masks, many people
might prefer to wear the masks, regardless of the spread of virus infection or
regardless the government order to wear them. This means the emergence of a
society that is extremely resistant against all airborne infectious diseases.
Conclusions
If this proposal is taken, the society can
take “order to wear the masks” instead of “lockdown”. The damage to the society
can be minimized even under the worst infection status.
References
[1] WHO coronavirus disease (COVID-19) dashboard.
[2] COVID-19
Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns
Hopkins University (JHU), ArcGIS. Johns Hopkins University.
https://gisanddata.maps.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6
[3] Y. Fujii, “Toward coexistence with the
new coronavirus”, Japanese Journal of Social Safety and Privacy, Vol.4, No.1,
pp.1-5, 2020. (in Japanese)
http://jjssp.e-jikei.org/ARCHIVES/vol04no01/JpnJSSP_vol04_no01_p01.pdf
[4] WHO Coronavirus disease (COVID-19): Herd immunity, lockdowns and
COVID-19
https://www.who.int/news-room/q-a-detail/herd-immunity-lockdowns-and-covid-19
[5] Y. Fujii, A. Takita and S. Hashimoto, “Development of a mask
that can almost completely shield viruses, and proposal of a social
infrastructure that eliminates the need for lockdown”, Japanese Journal of Social Safety
and Privacy, Vol.4, No.1, pp.6-10, 2020. (in Japanese)
http://jjssp.e-jikei.org/ARCHIVES/vol04no01/JpnJSSP_vol04_no01_p06.pdf
[6] Y. Fujii, A. Takita and S. Hashimoto, "A Helmet Type Mask
“Distancing-Free Mask”: An Engineering Solution that Eliminates the
Lockdown", Journal of Mechanical and Electrical Intelligent System, Vol.3,
No.3, pp.1-7, 2020.
[7]
Y. Fujii, A. Takita, S. Hashimoto and T. Yamaguchi, Japanese Patent Application,
No. 2020-113097.
[8] Y. Fujii, A. Takita and S. Hashimoto, Japanese Patent Application,
No. 2020-177304.
[9] J. Wang and G. Du, “COVID-19 may transmit through aerosol”, Irish
Journal of Medical Science,Vol. 189, pp.1143-1144, 2020.
https://doi.org/10.1007/s11845-020-02218-2
l This page is mainly copy from the following paper under the
permission by the publisher.
Y. Fujii, A. Takita and S. Hashimoto, "An
engineering approach for fighting COVID-19; Pseudo herd immunity through the
complete spread of the helmet-type masks", Journal of
Mechanical and Electrical Intelligent System, Vol.4, No.1, pp.1-5, 2021.
http://jmeis.e-jikei.org/ARCHIVES/v04n01/JMEIS_v04n01a001.pdf
[Publications by the Research
Team]
[1] Y. Fujii, A. Takita and S. Hashimoto, "A
Helmet Type Mask “Distancing-Free Mask”: An Engineering Solution that
Eliminates the Lockdown", Journal of Mechanical and Electrical Intelligent
System, Vol.3, No.3, pp.1-7, 2020.
[2] Y. Fujii，“新型コロナウイルスとの共存に向けて”, Japanese
Journal of Social Safety and Privacy, Vol.4, No.1, pp.1-5, 2020. (in Japanese)
http://jjssp.e-jikei.org/ARCHIVES/vol04no01/JpnJSSP_vol04_no01_p01.pdf
[3] Y. Fujii, A.
Takita and S. Hashimoto，“ウイルスをほぼ完全に遮蔽できるマスクの開発，および，ロックダウンを不要化する社会基盤の提案”, Japanese
Journal of Social Safety and Privacy, Vol.4, No.1, pp.6-10, 2020. (in Japanese)
http://jjssp.e-jikei.org/ARCHIVES/vol04no01/JpnJSSP_vol04_no01_p06.pdf
[4] S. Xu, Y. Cao, S. Hashimoto, Y. Fujii, A. Takita
and W. Jiang, “Control design applicable to a helmet type full-face mask”,
Journal of Technology and Social Science, Vol.4, No.3, pp.24-30, 2020.
http://jtss.e-jikei.org/issue/archives/vol04-no03/4-A108/JTSS_A108.pdf
[5] Y. Fujii, A. Takita and S. Hashimoto, "An
engineering approach for fighting COVID-19; Pseudo herd immunity through the
complete spread of the helmet-type masks", Journal of Mechanical and
Electrical Intelligent System, Vol.4, No.1, pp.1-5, 2021.
http://jmeis.e-jikei.org/ARCHIVES/v04n01/JMEIS_v04n01a001.pdf
[6] Y. Fujii, A.
Takita and S. Hashimoto，“軽量一体型「自由外出マスク」〜ロックダウン・外出自粛を不要化する「決め手」〜”, Japanese
Journal of Social Safety and Privacy, Vol.5, No.1, pp.6-10, 2021. (in Japanese)
http://jjssp.e-jikei.org/ARCHIVES/vol05no01/JpnJSSP_vol05_no01_p01.pdf
[7] Y. Fujii and A. Takita, " Personal respiratory
air purification device (helmet-type): Distancing-Free Mask (Prototype
No.5)", Journal of Mechanical and Electrical Intelligent System, Vol.4,
No.2, pp.1-5, 2021.
http://jmeis.e-jikei.org/ARCHIVES/v04n02/JMEIS_v04n02a001.pdf
[8] Y. Fujii and A. Takita, " Booth-type of
Personal Respiratory Air Purification Device: Distancing-Free Booth (Prototype
No.1)", Journal of Mechanical and Electrical Intelligent System, Vol.4,
No.2, pp.6-12, 2021.
http://jmeis.e-jikei.org/ARCHIVES/v04n02/JMEIS_v04n02a002.pdf
[Patents by the Research Team]
[1]
Y. Fujii, A. Takita, S. Hashimoto and T. Yamaguchi, Japanese Patent Application,
No. 2020-113097.
[2] Y. Fujii, A. Takita and S. Hashimoto, Japanese Patent Application,
No. 2020-177304.