[sgt_doofey]

If you're going to go in to some confined spaces beforehand, just make sure they are ventilated extremely well before going in to them.
Having worked in a vintage in a winery and having heard of people entering confined spaces and dying from carbon dioxide poisoning quite rapidly, I'd be very cautious with confined spaces. CO2 is heavier than oxygen and sits at the bottom of tanks and so forth.
In a winery, it's a minimum of a two person job to enter a confined space. One to go in fully harnessed with a tow line, and a spotter outside who can quickly pull the line to drag the unconscious person to them and drag them out. They also say to have a third person nearby should they need to go for help. They also test the quality of the air for CO2 before allowing someone to enter.