SafetyRob:I disagree with safety Joe. Both inert gases and CO2 can kill you, by the means of displacing oxygen. It will depend on what type of confine space your workers will be working in, that will determine what precautions need to be taken. Confine space can be a wide range of applications, so each procedure can be different depending on the clients recommendation, your company or Government reg. But you must meet the highest PPE required by either organization, but also you cannot downgrade protection.
I guess you didn't read my whole comment. wear I said "niether one will hurt you other than displace the oxygen in the confined space." since this is a safety professional bullitin board, I figured that all here would be aware of the danger of displacing the oxygen in a confined space without having to go into detail.
BTW I said they will displace the oxygen.