the safest way is add it by taping it on the back, but it would mean an extra layer on your card. depending on your design or how much lace you are using, this may not be practical.
I would use the thinnest Red Line tape as possible if you are attaching to the front, as like you say dust could get through, alternatively cover the edge with another embellishment.
Looking forward to seeing your invites, please do share them with us xx
