Similar to damage from inhaling caustic fumes. To what extent added lung capacity can be developed afterwards I don’t know. But if you are older, it’s probably minimal.
So saying someone survived can be relative. So if you have some RW relative poo-pooing the disease, point this out. A person may be a survivor but have permanent lung damage, meaning possibly disabled, or having a lower quality of life. As someone who is very active, and even in middle age does a lot of very physical activities including forest management, this is a very scary thing to me.
In America, “Liberty” means “Free to Die in Service of Capital” - Amfortas the hippie