Originally posted by TheHulkster
The use of the term "particularly" implies a small need to breathe.
He didn't understand the extent of his own powers here.
This story happens in the middle of the Kryptonite X arc, where green K gas in Cyborg Supermans fortress was filtered through The Eradicator and transformed into a chemical that initially powered Superman up to full power, and resulted in him gradually taking in far more energy than he could burn off until his muscles swelled like The Hulk and his heat vision switch was stuck to "on".
The crossover with Icon happens before his powers grow beyond his ability to control, but after he gets lost in space thanks to Lobo and he spends months wandering aimlessly without needing to breath.
Since previously, Superman drowned at the bottom of the sea fighting with Aquaman, he was rightly questioning exactly where his new limits were.