Posted By Mike Draper We are often called on to design, engineer and construct process systems involving inert atmospheres, typically nitrogen. I'm pretty well served on safety data for nitrogen, understanding the hazards and risks, confined space entry requirements, isolation/permit systems, etc. The thing I don't have is an actual medical explanation of the effects of oxygen deficiency, in terms of its immediate physiological effects(i.e. how a person would feel and react when deprived of oxygen) or on the impact on the cardio-pulmonary systems (from breathing, through gas-exchange in the lungs and then down to cell level). The BOC MSDS for nitorgen is a little hazy and the best I've got is a US safety bulletin. Does any one have or know of a half decent explanation that they could share or point me at? Thanks in advance Mike