Hello. Botrytis mold or Grey mold spores are everywhere. Please look it up on Google; Botrytis. They are just waiting for the right conditions to sprout. Unfortunately cannabis buds can provide that condition. Inside you can clean your air, but outside your at natures mercy. There is no real defense against it at this point in your flowering. You don't want to spray fungicide on the buds your going to smoke. See what Mr. google has to say. Good Luck. Chuck.