Luckily there all the guards were out and there were none of the guards he had to worry about, he had 2 minutes before the guards entered the prison again to patrol.
There were no environmental differences for each prison level, what differentiated them was the oxygen content at each level. Every descending level prison, the oxygen content will be depleted, so prisoners will find it difficult to take intense action to escape. But if the inmates could survive the low oxygen content, they would still have a hard time escaping because they were in the dungeon.
When Evan had reached prison level 2, he heard that Velorina's breathing rate increased. He forgot to tell them about the torture of being imprisoned by the Western Empire.