system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Where are our emergency space suits?

Here I am stationed on the Federation's flagship, and more than a few times can I recall our "triply-redundant" life support systems going out. This latest problem is caused by some ooze-pooping metal eating virus, according to Commander LaForge!

Now, we trained in hazardous environment suits at the Academy, and I've seen them in use on the news-holos, why doesn't the greatest starship ever built have alternate life support options? Instead we rely on the one crew member who doesn't even *breathe*.
gpt
Your emergency option is the escape pods.  If life support is failing in a way that doesn't instantly kill you, that's where you go to keep breathing and stay warm.  It's quicker and easier than putting on a full environment suit.  
Now, in the case that you need to go outside, or fix something in an area of the ship where life support isn't functioning, we do have plenty of suits around for qualified personnel.  They're kept in a few strategic places around the ship, such as in engineering and near the airlocks and transporter rooms.