Well both suits were wide open in the head/hood area. And it didn't look like they had popped open or come undone----they were simply open.
Heck a simple 1940s surgical mask would have been MORE safe from germs than the open bottomed hood!
By the same token and old fashioned 'muffler' scarf over the mouth would have been better against breathing in the cold air! LOL.
It was just awful in both a practical and story-telling sense. A total fail. Just give them an 'off the rack' parka deal.
And another case where they thought they had to do something 'futuristic' when they didn't.
How much better were the simple sickbay sheets/blankets in WNMHGB than the stupid 'futuristic' whatever that sickbay had after that?
And why do away with the nice landing party jackets from Cage and have the phaser/communicator 'futuristically' stuck by Velcro to the belt?