I would jus stick to exhaling jus once. I've herd tht ur lungs use the thc quite rapidly. The recycled smoke mos likely has mor carcinogens so re inhaling is worth the effort. I was upsatirs,sis was down n livin room cheifin. I hadn't smoked in a while n her fumes from down stains gave me a slight tingle. Coulda be the used smoke or the joint? Mayb both