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Cigarettes aren’t good for us.

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That’s hardly news--we’ve known 
about the dangers of smoking for decades.

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But how exactly do cigarettes harm us?

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Let’s look at what happens 
as their ingredients

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make their way through our bodies,

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and how we benefit physically 
when we finally give up smoking.

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With each inhalation,

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smoke brings its more than 5,000 
chemical substances

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into contact with the body’s tissues.

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From the start, tar, 
a black, resinous material,

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begins to coat the teeth and gums,

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damaging tooth enamel, 
and eventually causing decay.

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Over time, smoke also damages 
nerve-endings in the nose,

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causing loss of smell.

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Inside the airways and the lungs,

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smoke increases 
the likelihood of infections,

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as well as chronic diseases
like bronchitis and emphysema.

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It does this by damaging the cilia,

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tiny hairlike structures whose job it is 
to keep the airways clean.

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It then fills the alveoli,

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tiny air sacs that enable the exchange 
of oxygen and carbon dioxide

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between the lungs and blood.

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A toxic gas called carbon monoxide 
crosses that membrane into the blood,

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binding to hemoglobin

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and displacing the oxygen

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it would usually have transported
around the body.

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That’s one of the reasons smoking 
can lead to oxygen deprivation

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and shortness of breath.

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Within about 10 seconds,

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the bloodstream carries a stimulant 
called nicotine to the brain,

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triggering the release of dopamine 
and other neurotransmitters

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including endorphins

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that create the pleasurable sensations 
which make smoking highly addictive.

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Nicotine and other chemicals 
from the cigarette

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simultaneously cause constriction 
of blood vessels

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and damage their delicate 
endothelial lining,

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restricting blood flow.

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These vascular effects lead 
to thickening of blood vessel walls

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and enhance blood platelet stickiness,

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increasing the likelihood 
that clots will form

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and trigger heart attacks and strokes.

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Many of the chemicals inside cigarettes 
can trigger dangerous mutations

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in the body’s DNA that make cancers form.

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Additionally, ingredients like arsenic 
and nickel

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may disrupt the process of DNA repair,

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thus compromising the body’s ability 
to fight many cancers.

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In fact, about one of every three 
cancer deaths in the United States

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is caused by smoking.

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And it’s not just lung cancer.

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Smoking can cause cancer 
in multiple tissues and organs,

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as well as damaged eyesight

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and weakened bones.

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It makes it harder 
for women to get pregnant.

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And in men,
it can cause erectile dysfunction.

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But for those who quit smoking,

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there’s a huge positive upside

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with almost immediate 
and long-lasting physical benefits.

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Just 20 minutes after 
a smoker’s final cigarette,

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their heart rate and blood pressure
begin to return to normal.

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After 12 hours, 
carbon monoxide levels stabilize,

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increasing the blood’s 
oxygen-carrying capacity.

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A day after ceasing,

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heart attack risk begins to decrease as
blood pressure and heart rates normalize.

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After two days,

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the nerve endings responsible 
for smell and taste start to recover.

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Lungs become healthier 
after about one month,

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with less coughing 
and shortness of breath.

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The delicate hair-like cilia 
in the airways and lungs

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start recovering within weeks,

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and are restored after 9 months, 
improving resistance to infection.

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By the one-year anniversary of quitting,

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heart disease risk plummets to half
as blood vessel function improves.

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Five years in,

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the chance of a clot forming
dramatically declines,

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and the risk of stroke 
continues to reduce.

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After ten years, the chances 
of developing fatal lung cancer

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go down by 50%,

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probably because the body’s ability 
to repair DNA is once again restored.

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Fifteen years in, the likelihood 
of developing coronary heart disease

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is essentially the same 
as that of a non-smoker.

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There’s no point pretending 
this is all easy to achieve.

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Quitting can lead to anxiety 
and depression,

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resulting from nicotine withdrawal.

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But fortunately, 
such effects are usually temporary.

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And quitting is getting easier,
thanks to a growing arsenal of tools.

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Nicotine replacement therapy through gum,

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skin patches,

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lozenges,

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and sprays

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may help wean smokers off cigarettes.

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They work by stimulating 
nicotine receptors in the brain

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and thus preventing withdrawal symptoms,

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without the addition 
of other harmful chemicals.

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Counselling and support groups,

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cognitive behavioral therapy,

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and moderate intensity exercise

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also help smokers stay cigarette-free.

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That’s good news,

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since quitting puts you and your body 
on the path back to health.