Continuous or simple tense? Which to use?

How would you say these 2 sentences please?

1 There is air constantly going through/There is air that constantly goes through your shoes because of the little hole on the side of your shoes making sure your shoes air out and never smell bad. (how would you rewrite this?)

2 You can smell it when you are wearing them/when you wear them/while you are wearing them. (when could you use WHEN) which when would you use?)

Thank you