: Is 2nd hand smoking worse than 1st hand smoking I have heard many things about smoking and a main issue as of one being that 2nd hand smoking is worse than 1st hand smoking itself? (I do not smoke I am just around someone

TL;DR

Yes, if one was to inhale the same amount of smoke passively as smokers inhale actively, it would be more dangerous. This is hardly the case though, as smokers also inhale parts of second hand smoke, and because as always, dosis facit venenum.

Risk of Second Hand Smoke

Risk of developing cancer

Exposure to secondhand smoke raises the risk -- by as much as 30 percent [1.3 times] -- that others will get lung cancer and many other types of cancer, it can lead to emphysema, and it is bad for your heart.

Source: WebMD, Emphasis Mine, Annotation Mine

The lower risk of developing cancer is because passive smokers don't inhale the same amount of smoke - you usually walk past a smoker and not stand right next to them until they have finished their cigarette.

Inhalation of toxic fumes

There are 2 types of tobacco smoke:


Mainstream smoke, which is directly inhaled through the mouth end of the cigarette
Sidestream smoke, which comes from the burning tip of the cigarette


Second-hand smoke is made up of sidestream smoke and
exhaled mainstream smoke, mixed with the surrounding air.

Sidestream smoke is about 4 times more toxic than mainstream smoke,
although people inhale it in a more diluted form. This is because
sidestream smoke contains much higher levels of many of the poisons
and cancer-causing chemicals in cigarettes, including:


At least 3 times as much carbon monoxide
10-30 times more nitrosamines
Between 15–300 times more ammonia


Source: cancerresearchuk.org

However, the total amount of toxic fumes passive smokers inhale is less than what smokers inhale, because the former are not exposed to smoke as often as the latter.

Risk of Developing Heart Diseases or Strokes

Breathing secondhand smoke can cause coronary heart disease, including
heart attack and stroke. Know the facts:


Secondhand smoke causes nearly 34,000 early deaths from coronary heart disease each year in the United States among
nonsmokers.
Nonsmokers who breathe secondhand smoke at home or at work increase
their risk of developing heart disease by 25–30%.
Breathing secondhand smoke interferes with the normal functioning of the heart, blood, and vascular systems in ways that increase
your risk of having a heart attack.
Even briefly breathing secondhand smoke can damage the lining of blood vessels and cause your blood to become stickier. These changes
can cause a deadly heart attack.


Source: cdc.gov

Again, the risk is lower than the risk of smokers because it is only an exposure during work or at home and are not expected to inhale the same amount of smoke as bystanders as smokers do.

Risks of First Hand Smoke

Risk of developing cancer

People who smoke cigarettes are 15 to 30 times more likely to get lung cancer or die from lung cancer than people who do not smoke. Even smoking a few cigarettes a day or smoking occasionally increases the risk of lung cancer. The more years a person smokes and the more cigarettes smoked each day, the more risk goes up.

Source: cdc.gov, Emphasis Mine

Toxic fumes

Cigarette smoke is a mixture of over 4000 chemicals, many of which are
harmful to the human body. All currently available tobacco products
that are smoked deliver substantial amounts of toxic chemicals to
their users and those who breathe their smoke.

Of the more than 4000 chemicals present in cigarette smoke, more than
60 have been identified as cancer causing chemicals, 11 of which are
known to cause cancer in humans and 8 that probably cause cancer in
humans.

With approximately one non-smoker dying due to secondhand smoke
exposure for every eight smokers dying of smoking-related disease it
is no surprise that secondhand smoke has been designated a known human
carcinogen (cancer-causing agent). Further, about half of regular
smokers will die of a smoking-related disease and have a reduced life
expectancy of about 13 to 16 years as compared with non- smokers.

Source: Australian Department for Health, Emphasis Mine

Risk of Heart Diseases and Strokes

If you smoke, your chance of dying from a heart attack is 2 to 3 times
greater than that of a person who does not smoke. About 1 out of 4
heart attacks is believed to be directly related to smoking. Smoking
is a much more important risk factor for a heart attack than high
cholesterol, obesity, high blood pressure, or stress.
A person who smokes is twice as likely to die from a stroke as a person who does not smoke.

Source: WebMD, Emphasis Mine

If you have children

Second hand smoking is especially damaging to children:

Every day millions of children in the UK are exposed to secondhand
smoke, which puts them at increased risk of lung disease, meningitis
and cot death. Treatment, hospital and GP visits for secondhand smoke
related illnesses cost the NHS more than £23.6 million each year.

Source: gov.uk, Emphasis Mine

Early exposure to chemicals is a lot more damaging than during adulthood.

Passive smoking causes lasting damage to children's arteries,
prematurely ageing their blood vessels by more than three years, say
researchers.

Source: BBC.com

This can lead to early heard attacks and other coronary diseases.

Exposure of unborn children to tobacco smoke may also increase the
risk of miscarriage, low birth weight and sudden infant death syndrome
(SIDS), or ‘cot death’. There is strong evidence that the babies of
mothers who smoke after birth have more lung diseases in their first
year of life and have double the normal risk of serious airway
infections.

Source: Gov.au

If you have kids, you definitely should follow the advice below.

What you can do

You can protect yourself and your family from secondhand smoke by:


Quitting smoking if you are not already a nonsmoker
Not allowing anyone to smoke anywhere in or near your home
Not allowing anyone to smoke in your car, even with the windows down
Making sure your children’s day care center and schools are tobacco-free
Seeking out restaurants and other places that do not allow smoking (if your state still allows smoking in public areas)
Teaching your children to stay away from secondhand smoke.
Being a good role model by not smoking or using any other type of tobacco.


Source: cdc.gov

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