[@Burning Kitty] I just meant they could have taken measures to fix it. If I remember correctly the Krogans had achieved some small percentage of increased conception rate or something like that... I remember a conversation to that effect with Kesh. I'm proposing something similar for the quarians. They could survive without their masks aboard their ark and shuttle craft, but would have to use them when meeting new environments and species.

Here's the link
[url]https://s-media-cache-ak0.pinimg.com/564x/88/12/96/881296ace256d8648da612e2082606e5.jpg[/url]