have you ever seen the inside of a lung sugar? it doesnt have much place to cycle.....once its in there its inthere, and even if it was, how would holding your breath allow it to cycle threough your lungs? the best way to get the smoke throughout all your lungs is take deep breaths....not really a matter of time. and its just common fucking sense that holding it in is worse for your lungs. think of all the bad shit floating around int he smoke....holding it in their gives it a little more time to attach to the side of your alveoli's or however its spelled. that means its not good.