Why are bags of chips bought at high altitude not swollen?

Question

When I buy a bag of chips at sea level, and take them up to the mountains, the bag is swollen. I get why that is. However, when I purchase a bag of chips from a store in the mountains, those bags of chips are not swollen. Why is that?

Air leakage over time seems to be the obvious response, but I don't think this can be the case, otherwise how can the chips stay fresh if the bag isn't air tight?

Answer 1

It is a serious problem for vendors up in the mountains. Check "High Altitude Living". Probably the reason why you don't see swollen packages in stores is somebody took the effort to work around the problem, such as getting products from distributors that also operate at high altitudes.

Answer 2

Was that during summer or winter times (hot or cold)? I say this because at any air-filled bag the air there suffers if any change in temperature. At high alts there's a really a problem of cold, lot colder than at sea side level. So when you fill the bag (air tight one, and the chip bag really is) with a lot of air, along chips, at sea level when you take it and keep it to high alts you'll see that is deflating itself, even though it should inflate harder because of the expansion of the air in the bag is not balanced by the environmental air from outside (see the weather balloons)
Hope I was useful
Dfriend :)

Answer 3

Under the equalized pressure after the air slowly leaks out, there is very little flow in either direction. You could consider it negligable. But do keep in mind. Those chips wont stay fresh indefinatly...They will go stale if they sit around too long - even unopened. I hope this helps, jason

Answer 4

they are probably not that air-tight. try leaving a bag unopened for a bit. (i know it is hard to resist the temptation to eat up the chips :)

I mean it's not like they package those chips at high altitude.