My uncle can hold his breath for 2.5 min that means that in one breath you can have enouf oxygen for 2.5 min befor he starts getting light headed and passes out yes lack of oxygen cause a dizzy effect and brain cells distroyed. If my uncle took a breath and Exhailed after 5 sec think he could Stay underwater for 2.5 min after that? No why? because he holds his breath for the 1st 30 sec or so of the dive to absorb oxygen.... Im not arugueing and i donl;t care how you smoke but I'm going hold it for my crappy 18 sec wich is barly anytime to really deprive the brain of oxygen, Thank you for consern i apperate it:smokin: + im saying i can stay high longer due to it not that it a Higher high ( due to lack of oxygen)