I remember having a conversation with Tali saying that they still had to wear suits on Rannoch. Others I have spoken to about this just disagreed with me completely, saying they only wore suits on the Flotilla and such. http://www.awkwardzombie.com/index.php?page=0&comic=101711 helps my argument, thinking that there was a conversation in the game that mentioned it.
Think about, if they had to wear suits on Rannoch how did they get past the stage where they couldn't build sterile suits that probably accounts for most of their history. Aethyta on Illium implies that she saw the Quarians without her suits. Also, conversations with Tali I believe make it clear the the Quarians always had a fragile immune system, but it was managable until they where forced off their home planet and the sterile environments of the ships completely destroyed it.
One of Tali's logs on the former Quarian colony of Haestrom mentions: "our ancestors walked these halls with uncovered heads". There is also some piece of dialogue (with Aethyta? can't remember), which states that many of the people living on the Citadel are old enough to "remember what the Quarians looked like outside their suits". From what I gather they only started systematically wearing their suits some time after their exile. TiberiusYakushev 08:09, October 29, 2011 (UTC)
^ Which would make sense, seeing as how immune system atrophy is a gradual process, and that the Geth War started in 1895, exactly 288 years before ME1. In Citadel terms, that's not a very long time (humans are still considered newcomers nearly 30 years after first contact, the turians have had full Council membership for roughly 1200 years, the volus have been on the Citadel for more than 2000 years; you get my point). Asari can live for a thousand years, so it's not much of a stretch that the Citadel's asari population would be able to remember what quarians looked like. 188.8.131.52 12:04, October 29, 2011 (UTC)
Yeah, I'd think that if they had to wear suits even on their homeworld, their biology wouldn't have been able to reap the benefits that the planet's bacterial life provided. Plus, I'm sort of inclined to think that if they weren't able to take off their suits - at least part of the time - even on their own planet, they probably wouldn't feel quite as strongly about taking it back as they do. Might as well just colonize another world.
For all the good that taking back Rannoch would do them. I mean, even ignoring the costs (in resources and life) of unleashing full-on war on the geth, I'm pretty sure that at one point Legion says that Rannoch's surface is still covered in the toxic remains of the original war. Odds are, even if the quarians managed to defeat the geth and move back to their planet, they'd probably still have to wear the suits in order to not fall prey to the now-poisonous environment.
I wonder what makes people answer this "question" in a serious tone. Concerning Rannoch, if I remember right, Legion says that geth have been preparing the planet for the return of quarians, and ecology is in a good state. The planet should be habitable.
Before the Geth war, they did not wear suits. K1LLERAnish 08:00, October 30, 2011 (UTC)
The quarians have only begun wearing environmental suit systems relatively recently (in terms of Citadel time). It would seem likely that Rannoch and the other colonies would have been more hostile to the quarians fragile but adaptive immune systems but not enough to cause them serious harm; if their own home was lethal, there wouldn't be any quarians right? After all, Tali'Zorah mentions the theory that the quarians evolved to have weak immune systems so as to contract beneficial viral infections and spread pollen and such. Without such an environment constantly adapting them, their ability to fight most ordinary infection is almost nil, hence the suits aboard the Fleet.