What makes "indoor atmosphere" different from "the outdoors"?

Factual Questions
1

This is a totally weird question, and I might not even be using the correct terminology, so please bear with me.

I live in an apartment with no AC, so in the summer, I leave the windows open. I have things like a TV, a computer, books, and so on - things that would be quickly degraded if they sat outside all of the time - but they don’t go to pot in here, even though the only *legal * difference between them being in this apartment instead of, say, outside on the sidewalk is that there are some walls and a ceiling between them and the sidewalk.

The atmosphere and the air - the environment - is the same between the two, especially with the windows open. What keeps my books from getting moldy and wrinkling up, my computer and TV being destroyed in the way that they would be if they were “exposed to the elements?” Is it just that being legally indoors, even with all the windows open, keeps the sun, wind, and rain off of them, so they stay in decent condition?

I know it’s a weird question, but it’s something I’ve been thinking about lately - how is the computer that’s only six feet away from the open window not the same as the computer sitting on the sidewalk down below? Or is it?

2

Maybe direct sunlight is the missing factor. It’ll do a number on lots of things given time.

3

I’d say it’s water more than anything else. Water infiltration is the biggest problem with badly constructed homes, it screws up everything it touches. Wood rots, metal rusts, mold grows. A 2x4 that will last 100 years dry will last 1 year if it gets wet often enough. Put something like a computer or a book out of doors, and it will be just fine until it rains.

4

And to follow up on the “water” answer, it occurs to me that I’ve never seen dew fall in an apartment or home, probably because the inside of the building isn’t as subject to drastic temperature changes and radiational cooling. So even in humid weather, objects inside the house aren’t going to be subjected to the kind of water damage and weathering you’d see outside.

5

You could ask Fuel