Help how long can my babys go with out o2

Got up this morning everything was fine I'm gone for 4 and 1/2 hours come back my electricity is off changing out a Transformer and I guess my Powers been off for an hour and a half to two hours and I went and talked to them they said another hour I looked at my roots and they are starting to turn brownish are they going to die or will they bounce back if I can get oxygen to them

I've had pumps down for days. Never noticed a problem on bigger plants. What you can do is blow in them for now with your mouth if you're worried. I've done that in the past lol