Make sure to empty the bag out at the end of each day and allow it to air out overnight. This will help to prevent any odors from building up inside the bag. Do not place lunch or snack boxes directly in any compartment of the bag. Instead, put them into tiffin bags before placing them in school bags. If they are smelly then you can place a small container of baking soda inside the bag overnight to absorb any moisture and odor.