When I read it, I thought it should have been "leaving" Otherwise, the American Academy of Family Physicians suggests, leave the wound open to the air and keep it dry to help it to heal faster.
Leave is correct. It is parallel to Cover at the beginning of Step 2.
- Cover the wound only if A or B. Otherwise, leave it open to the air and keep it dry.
If you said leaving, you would turn "leaving it open" into a subject, and you would have to continue the sentence by saying something about it. E.g. - Cover the woun