Custom oxygen level bar help

New to this so forgive if I am in the wrong part of the forum. In the game I have a custom bar for Oxygen. If the oxygen is to high the player takes dmg. If to low, as if under water, they start taking DMG. Right now I am just setting up the bar. Will worry about how to make work a little later. In the image I go to As Third Person Character I try to get Oxygen but nothing is found. Is this something that will have to be scripted or can I find something similar under another name? Thanks for any guidance.