Good morning .
I am slightly confused as in your title you have said mines but then in your message description you have said caves , I shall answer this with information about ?mines? .
All mines have a slight natural air flow if they have a minimum of two open adits that are connected it causes the air to come in one and pull through depending on how the levels work , they can have one large adit some times it?s enough to still walk around the hole mine anyway and you can feel the air pressure change on various levels inside of the mine , bryneglwys slate mine on the lefel fawr level has a very strong air flow due to its shaft on the level and the massive water ingress pulling the air inside and back out .
Rember also atmospheric pressure changes this every minute of every day also
Regarding caves I shall not answer because I have no clue at all compared to the other members
I would try to enlarge on your message so people can help you more and explain your interest / research etc I hope this has helped though .