The deadly air is causing him difficulty, and he only makes it half way to the door before passing out. Everyone's pretty much unconscious at this point, but that Starfleet training is paying off. Janeway orders the magic button be pushed. They push it. Things really heat up.
People do start passing out.
Holodoc calls from sickbay. It takes a while for anyone to be conscious enough to respond. Chakotay finally does. Holodoc reports cheerfully that the infection is completely eradicated and the danger is past. Dolby and the others pry open the cargo bay doors and stumble through the poison gas and drag Tuvok and Garen to safety, working like a well-oiled team.