Hiroseʼs column

In the process of developing the Hero Inner-Mask, I have answered the following questions:ʻWhy do people inhale and exhale air through their nosesʼ?
ʻWhy has the nasal cavity evolved so thin that it can get clogged by empyemaʼ?
When we were aquatic animals such as fish in ancient times water flowed through our mouths
and exited through our gills; therefore, freshwater (oxygen) was pumped into the gills.
However, our ancestors that emerged to the ground began to inhale and exhale air throughtheir noses. This structure forced the re-inhalation of exhaled air composed of a low oxygen
concentration through the same hole. In particular, I have never questioned the structure
related to pulmonary respiration. This structure appears to be similar to eating and defecatingfrom the mouth, which is very irrational.
Why have we evolved in this manner? To answer this question, I conducted a literature review
on physiology and observed that the major issues with animals that were once aquatic wererelated to their living tissues, which had to be preserved in a wet state (similar to that in water)
after they emerged from the water and reached the ground. I, therefore, speculate that theprocess of evolution from gill respiration to lung respiration is as follows:
Our ancestors who emerged from the water and reached the ground had a gill-breathingmechanism, which led them to create a one-way airflow, similar to gill breathing, that would
allow them to breathe efficiently. However, the trachea, which is the passageway into therespiratory tract, became dry due to the outside air; therefore, it was difficult to maintain thewet state. At that time, there was a species that breathed through lungs with the same air inlet(trachea), which was always maintained wet by exhalation. As a result, this species easily
adapted to environments composed of dry ground.
However, species that had a large hole (nostril) slowly exhaled air drifts around the hole.
Subsequently, during inhalation, the drifting exhaled air was inhaled again. In this case, theoxygen intake efficiency in respiration was poor.
In contrast, species that had small nostrils exhaled from the narrow nostrils far away at a highspeed, improving their breathing efficiency, as the inhaled air was not mixed with the exhaled
air floating around the nose. This resulted in a higher survival rate.
We inhaled and exhaled air through the same nose; therefore, the nostrils became narrower toavoid the exhaled air being mixed with the inspiratory air. Problems would arise if the only
nasal cavity of the species would become clogged; therefore, they had two nasal cavities. The
nasal structure evolved similar to that observed in our study.

The figure above is a simulation material reported by Professor Sera of Kyushu University.
During inhalation, the stationary air around the nose is slowly inhaled into the nasal cavity,
whereas, during exhalation, the air is vigorously blasted from the nasal cavity, even if theairflow (trachea) is the same. Although the flow of inhalation from the nostril and that of theexhalation are different, the process prevents the mixing of inhaled and exhaled air, improving
the breathing efficiency, which appears to have never been interpreted.
This discovery is an example of my understanding of the natural respiratory mechanism to try
to create an industrial product based on the respiratory mechanism. This is a typical exampleof ʻanalysis by synthesisʼ process in the field of robotics.
The mask we currently wear interferes with the exhalation-inhalation separation mechanismthat the nose originally had, therefore preventing the exhaled air from being blown far away.
This is considered the fundamental principle of discomfort.
In contrast, the HERO Inner-Mask guides the exhaled air from the nose to the lower part
inside the mask. This air is filtered from the lower non-woven fabric and then assists
inhalation from the upper non-woven fabric.
This unique device considers the exhalation-inhalation separation mechanism of the humannose, allowing easier breathing even when wearing a mask.

Shigeo Hirose
HERO Lab.