Seth is glad he took the time to secure his grip, because the sound makes him jump more than is safe right now.

Without pausing to consider what he might find above, he reaches up and pushes the hatch open, and the sight of open air, however smokey, is an amazing relief. He doesn't do great underground.

He climbs out and steps onto the grass, glancing around, but he can't see any people, armed or otherwise, at least not on first look. So rather than running for cover, he turns back to make sure Daniel gets out alright.