reasons to give up smoking

Reasons to give up, quit smoking immediately:
Even one cigarette slows down your cilia. Heavy smoking kills the cilia.
Mucus and dirt pile up and germs don't get swept out. Smokers get sick more often than non-smokers.
Tar sticks to the insides of your lungs and can cause cancer.
Nicotine (a drug in tobacco) makes your blood vessels smaller. That means your heart has to work harder to pump the blood.
A very dangerous gas called carbon monoxide is in cigarette smoke. It is also found in car exhaust! It gets into your blood and doesn't let the oxygen in. That means your heart has to work even harder to get enough oxygen for your cells.

atmospheric air composition

Composition of atmospheric air and expired air in a typical subject.
Note that only a fraction of the oxygen inhaled is taken up by the lungs.
Component Atmospheric Air (%) Expired Air (%)
N2 (plus inert gases) 78.62 74.9
O2 20.85 15.3
CO2 0.03 3.6
H2O 0.5 6.2
100.0% 100.0%