SOLVED. Juvenile Fiction about a man who felt sick if he came down from the mountains. [s]

[Saeed]

The story is about a man who lived high in the mountains and felt really sick and sullied when he came down. I remember there was a specific altitude above which he felt purity and peace, something like 2000 or 2500 meters above sea level (a round number). He came down to town only for errands, and he hated it. He couldn't stand living in the low altitudes amongst other people.
This was what I can remember clearly from the book. I think at some point in the story for some reason he got stock down in the city and things started going wrong, but I'm not sure.

I read this book when I was in high school, in mid 90's. I remember it seemed old back then.
I read the Persian translation of the book. It must have been from the 70's or earlier since it looked like a pre-revolution print. I think the cover was blue.
No clue about the author.

[Lobstergirl, au gratin]

Where is it set - country, region?
Author's nationality?
Author's gender?

[Saeed]

I don't remember those details, unfortunately.

[Lobstergirl, au gratin]

The man's ethnicity or race?

[Saeed]

I am not sure really. Maybe a European in the Alpes. But I could be wrong. Could be a South American in the Andes.

[Orsolya Könyvtáros (formerly Memp)]

Secret of the Andes, by Ann Nolan Clark?

First published in 1952, not sure about translations.

The air was hot and heavy and thick and difficult to breathe. Cusi felt slow and stupid and sleepy. He had never felt like this in the thin, cold air of the mountaintops [...] His feet felt heavy and as if they did not belong to him. "My feet are two heavy somethings that I pick up and put down and pick up and put down," he told Chuto.

Chuto laughed. "It is because we are in lower country. You must remember that our home is thousands of feet above us."

Cusi was interested. He had not thought about altitude before. He had not needed to think about it. In the world he knew everything was high or higher.

[Saeed]

That should be it!!! Thanks a lot <3 <3

[Orsolya Könyvtáros (formerly Memp)]

You're welcome! I remember liking it when I was a kid but that was a long time ago. I'm going to have to read it again now.