This infographic explores the lungs of smokers vs non-smokers.
Non-smokers' lungs are pink in color and healthy while that of smokers is dark and mottled due to the accumulation of impurities from smoke.
An average human inhales 388 cu.ft. of air per day. This is the amount of air that fits into the trucks of 3 sedans. Out of this only 19 cu.ft is made of oxygen. Rest is all a combination of other gases.
To a smoker lesser amounts of oxygen are available as compared to the non-smoker. A smoker's lung has less capacity to absorb oxygen than that of the non-smoker's.