Effects of working in confined spaces with insufficient oxygen

We found that for some engineering operations, if the operation is performed in a confined space with insufficient oxygen, the quality of the operation will be affected, and there may even be certain dangers. So, in this case, what kind of impact will it have? Let's do a simple analysis of this problem.
In our experience, insufficient oxygen in confined spaces is a frequently encountered condition. Oxygen insufficiency can be caused by many factors, such as crowding by dense gases (such as carbon dioxide), combustion, oxidation (such as rust), microbial behavior (such as mouse decomposition), absorption and adsorption (such as wet activated carbon), work behavior (such as using Solvents, paints, cleaning agents or heat work) etc. can affect the oxygen content.
After entering, workers can be asphyxiated due to lack of oxygen, and excess oxygen may accelerate combustion or other chemical reactions.