244
A City on Mars: Reality kills space settlement dreams
(arstechnica.com)
This is a most excellent place for technology news and articles.
Infrastructure for distributing the air once it gets to the settlement is one thing. At least for now, though, Earth is the only place to get oxygen in life-sustaining quantities, which is the single source they're talking about.
Maybe you can posit harvesting oxygen from mineral oxides, hydrolyzing water if you can find it, or capturing an ice asteroid. Whether you split every atom of oxygen you breathe out of rust or lift them out of earth's gravity, let alone doing both for redundancy, it's orders of magnitude more energy and complexity than growing potatoes in Antarctica.
If we're talking about space colonization then "at least for now" doesn't apply any more.
There are vast quantities of oxygen available everywhere in the solar system. Extracting it is really not hard. There's a technology demonstrator generating oxygen on Mars right now. If you're arguing against space colonization because you're assuming that every bit of resources the space colony uses will have to be sent there from Earth, you're completely missing the basic concept of space colonization.