I've worked in manufacturing in the food industry in quality control. In the specific products I dealt with, we eliminated as much oxygen from the container as possible to keep the product as safe as possible. I never worked with chips or other similar snacks so can't speak to the methods used in it. What I was envisioning by using "pollution" was something like the smog which engulfed cities in the 70's though any befouled air would fit the definition.😌😊👍