50% of all packaging is used for food packaging. And in many cases food is not a "dead" product. Foods have always a life either intended or in case of bacteria, fungal and so on not wanted. We always have a respiration using O2 and producing CO2. Almost all these kind of life, either the product or the not wanted elements, are optimised to live in atmospheric conditions at 21% O2 and almost 0% CO2. In other climate the process is normally reduced.
Storage of food under another composition of air (headspace) in order to both upgrade quality and extend shelf life is a very old technology already well known in the Stone Age.