It's very good that you point that out.
I mentioned to you that we breathe about 20 kilograms of air a day. That's huge. That's enormous. The exchange of gases is especially fast, faster than that of solids and liquids, for sure.
Since 1982 the Japanese government has considered tree-bathing—it's called shinrin-yoku—a health activity. The Japanese measure blood pressure, heart rate, heart variation, the immune system, and finally the stress system very precisely, especially by dosing the cortisol in the blood.
For all those parameters, while you're in the green milieu, compared with the same people in the urban milieu, you have a very significant drop in blood pressure, comparable to a very good anti-hypertensive drug, simply by being among trees. Afterwards, they found out that trees emit a lot of what I'll call “tree proteins”. That's been known by botanists for years, but now we see they have a direct impact on man.
It's easy to understand. For example, tobacco is a plant. You smoke it; you have effects. Cocaine is a plant; when you smoke it, sniff it, or whatever, you have effects. It is deleterious, and it's the same for opium, etc. You have the direct influence of plants by air.
They are deadly or harmful.
However, we can have positive activity directly on various parts of our system, of our anatomy.
I'm thinking especially of our central nervous system, our cardiac system and our immune system.