An artificial environment in Lan space completely surrounds a planetoid too small to support these optimal-for-life conditions. Gravity systems create an atmosphere.
The planetoid is at a suitable position regarding solar wind from the Lan Star. The molecules needed for good breathable air are within the orbit (they are just usually dispersed in vacuum). The technology collects and keeps what is need, and gravity systems give a Lan Home world feel.
She lets go of the hands of the elLans, and stares at sky. So much is different.
Ami bolts forward and pushes her arms out like flying, she spins often in running about in circles.
Full of giggles and 'geee's, Ami is really off of planet Wroug.
She inter-mixes a straight-legged flips, both forward and sidelong. This goes on for a while. "First" and "second" enjoy this quite a bit, but they are in Lan space; they appear pleased but stoic.
After a bit, Ami comes back. "First" gets a lightly shaky hand, as Ami arrives.
Ami: "Constu ten z"
Ami, more slowly with breathiness: "Constituents of atmosphere...? What percentages...?"
"Second" and Ami discuss what the atmosphere percentages are. The oxygen is a couple of percent points higher here, which is kind of a large jump. Twelve percent on Wroug, but fourteen percent here; that is a one sixth higher amount of oxygen. Even among the Lan, they notice the higher oxygen level here. The Lan have well engineered body systems to account for these types of things.
Ami says it will be OK. She has practiced controlled breathing for a long time. They walk hand-in hand with Ami; but soon "first" lifts Ami and carries her.
Ami trembles while controlling her breathing, but gets a great view with her head on "first"s shoulder. The joy, which Ami has, is incredible; the view is (quite literally) other worldly.