How Long Does Secondhand Smoke Stay In Your System?

February 17, 2018

Jelly Bell

How Long Does Secondhand Smoke Stay In Your System?

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Although cigarette smoking is prohibited by the government at a range of public places like hospitals, public transportation or school, non- smokers are still at the high risk of absorbing smoke from the environment outside. Many people are wondering that whether the smoke they inhale from smokers is dangerous for their health or not.

If yes, how long does secondhand smoke stay in your system and what is its effect on your body? These questions will be clarified in the article below.

What is secondhand smoke?

Secondhand smoke can be called passive smoke or environmental tobacco smoke. Two types of burning tobacco smoke are mixed to create passive smoke, including:

  • Mainstream smoke which refers to the smoke exhaled directly from the smokers
  • Sidestream smoke which is released from a lighted end of a cigarette or other devices like cigar, pipe. This type of smoke is more harmful to your health than mainstream smoke due to the higher concentration of cancer- leading factors in it. Moreover, the particles in this smoke are also easier to enter your lung and your body’s cells than the other because of its smaller size.

Over 7000 chemicals are found in environment smoke. Hundreds of them are noxious for our body, and roughly 70 of those toxic chemicals can cause cancer. People can be exposed to involuntary smoke from various areas like in home, cars, workplaces or public places.

What are the dangers of secondhand smoke?

Smoking harms not only smokers but also their loved ones. Although inhaled smoke is less dangerous than the smoke coming from the cigarette tip, it still leads to various health problems for non-smokers, such as increasing the risk of heart attacks, lung cancer and other breathing problems (coughing, wheezing or difficult of breath).

secondhand smoke
Secondhand smoke is dangerous

Some studies showed that exposing to secondhand smoke in one hour in an enclosed space can provide a sufficient quantity of nicotine to bind receptors that are targeted by smoke exposure directly and causes alter the brain’s function of non- smokers. In case the exposure to secondhand smoke is prolonged, the nicotine levels in the brain will become higher and raise people’s vulnerability to nicotine addicted.

Click here to see HOW LONG DOES IT TAKE TO GET ADDICTED TO NICOTINE if you are wondering about this question.

Secondhand smoke is especially dangerous for vulnerable groups, including infants, children, and pregnant women.

  • Children: Typically, children breathe faster than adults and their systems have not developed entirely. Thus, children tend to exhale more secondhand smoke into their lungs and this cause a range of issues like sudden infant death syndrome (SIDS), chronic cough, more respiratory infections (bronchitis or pneumonia), asthma attack and ear infections [1].
  • Pregnant women: Women who breathe secondhand smoke during pregnancy are more likely to have babies with SIDS, low birth weight, limited mental ability, trouble with learning and have a high risk of premature delivery [2] [3].

Because of the serious consequences of secondhand smoke, “How long does it stay in your system?” is a question that we need to discover.

How long does secondhand smoke stay in your system?

Most of the people know that smoking is harmful to their health, but some of them are wondering whether secondhand smoke that is inhaled from smokers affect their body. If yes, how long does it stay in their body?

In reality, there is no clear study regarding the stay of secondhand smoke in your system. However, it is showed that its stay does depend on the amount of it that penetrates into your body. The longer time you contact with secondhand smoke, larger its concentration accumulates in your body, and this leads to lower your body’s removal of nicotine from secondhand smoke.

Like smoking directly, secondhand smoke contains mobs of nicotine which is hazardous to your health. When nicotine from secondhand smoke comes into your body, it metabolizes into cotinine and mainly accumulates in bodily fluids such as blood, saliva, and urine. The nicotine removal from each region is dissimilar and depends on various factors.

  • Blood: With an appropriate amount of nicotine entering your body from secondhand smoke, it can be detected in your blood and exists in 1 to 3 days for nicotine and up to 10 days for cotinine.
  • Saliva: When reaching a certain amount, nicotine can be found in your saliva. This STAY OF NICOTINE IN YOUR SALIVA can vary from 10 hours after the last cigarette to 4 days depending on the nicotine’s concentration in your body.
  • Urine: If you contact with smoker frequently or live in a smoking environment, secondhand smoke can penetrate into your body and exist from one week to three weeks.

You can click HOW LONG DOES NICOTINE STAY IN YOUR SYSTEM to know more detail.

When and why do non-smokers need to do nicotine testing?

Nicotine testing is a test done to find whether a person uses tobacco and nicotine-containing products or not. Because nicotine utilization prolongedly leads to raising the risk of lethal diseases and causes a severe impact to an individual’s health, the companies often require this test to check their employees before hiring to ensure the quality of work.

Health insurance companies are also aware of the less healthy of smokers than non-smokers, so they charge higher premiums for the tobacco users. Because of above reasons, both smokers and non- smokers sometimes have to do this test if they apply for a job or buy insurances at some companies where request.

Knowing that how long does secondhand smoke stay in your system is very necessary. Many people, especially women think that they do not smoke so they will pass this test. However, you can probably get the positive result if you are one of the following cases:

  • You live or work with people who smoke habitually and share the air with them for years
  • You get into the car being driven by a person who smokes regularly.
  • You met your friends who were smoking and spent several hours on talking with them, even in the past 2 to 3 days.

Therefore, to be sure that you indeed pass the nicotine testing for getting a job, you should use an in-home test kit to check before you do the real test.

If you want to know more about the relation between tobacco and your body, click HOW LONG DOES TOBACCO STAY IN YOUR SYSTEM.

How to test nicotine from secondhand smoke in your body?

test nicotine from secondhand smoke in your body
Test nicotine from secondhand smoke in your body

To answer the question how long does secondhand smoke stay in your system, you need to test the level of nicotine in your body. Nicotine from secondhand smoke is tested similarly with the one from smoking tobacco directly. Cotinine, a byproduct of body’s metabolism of nicotine, is considered as an accepted indicator of tobacco usage or exposure. There are four basic methods to test nicotine and cotinine when it enters your system.

  • Nicotine and cotinine the blood sample: The appearance and amount of nicotine in your bloodstream can be determined through the blood test. This test is an invasive procedure and considered as a most accurate way to check. See HOW LONG DOES NICOTINE STAY IN YOUR BLOOD to find more interesting information.
  • Nicotine and cotinine in saliva sample: Saliva test is the most sensitive test (97.6% sensitivity) to detect nicotine in the body and estimate how much nicotine was consumed.
  • Nicotine and cotinine in urine sample: Collecting urine sample to do this test is more convenient and less invasive than the blood sample. This test is the most popular method to check nicotine for employment.
  • Nicotine and cotinine in hair follicles: Although nicotine testing from hair follicle is the most reliable way, it is not used frequently due to its high cost.

Nicotine test can also reveal the qualitative as well as quantitative results [4].

  • Qualitative testing: This test shows whether nicotine presents in your body or not.
  • Quantitative testing: It indicates the concentration level of nicotine in your system and gives us information about your smoking habits. This test can tell us whether you are an active smoker, a tobacco user who has quit lately or a passive smoker. With non-users, it can even tell if you breathe a substantial amount of tobacco smoke or not.

The stay of nicotine in your body varies based on many factors, see FOODS WILL FLUSH OUT NICOTINE FROM YOUR BODY and HOW TO GET NICOTINE OUT OF YOUR SYSTEM to help you understand more about the factors that influence the nicotine test.

Can secondhand smoke exposure produce a positive result?

Some people ask how long they exposed to secondhand smoke that could affect their result of nicotine test. The answer is that it rarely leads to a positive test for people who were around secondhand smoke only because of the following reasons:

  • Most tests measure the level of cotinine which is a metabolite of nicotine in your body to determine nicotine exposure. Nicotine does have a short half-life and can stay in your system in about 24 hours. On the other hand, cotinine can exist for several days in your body.
  • However, the absorption of secondhand smoke is normally not substantial to be accounted for in nicotine tests. Therefore, the trace of nicotine or cotinine is difficult to be considered as a positive test.

However, it is indicated that the level of cotinine required to activate a positive result is roughly 30 ng/ml. Typically, the cotinine concentration in non- smokers is less than 10 ng/ml [5]. Thus, if you are in nearby and prolonged contact with tobacco smoke, this can probably cause the positive result in your test.


How to avoid secondhand smoke?

avoid secondhand smoke
Avoid secondhand smoke

There is no safe level of environment smoke, so in order not to worry about how long does secondhand smoke stay in your system, the best way is to keep away from it. How to do this if we live or work with smokers for so long. Let’s follow the plan below:

At home

  • Hang out a sign: “No smoking” at your front door to notify for visitors in advance before going into your home.
  • If family members, relatives or someone ask whether they can smoke or not, don’t be afraid to tell them to step outside.
  • Remove all ashtrays
  • If you live with smokers, convince and support them to quit smoking
  • Teach your children how to request other people not to smoke around them. If they do not stop smoking, stay away from them.

In public areas and workplaces

  • Avoid indoor public places that allow smoking
  • Choose smoke- free care facilities: Eat and drink at 100% smoke-free restaurants or bars and so on.
  • Do not allow smoking in your vehicle
  • Tell your colleagues who smoke that smoking restriction is enforced at work.
  • Participating in the meetings about the policies of smoke-free
  • Assist your nearby organizations that are working to protect non-smokers.


To conclude, “How long does secondhand smoke stay in your system?” mostly depends on the time exposure with it and its concentration on your body. Involuntary smoke is responsible for thousands of disease cases. Thus to protect your health and your loved one, we should say no to tobacco and strictly comply Tobacco Control Law.

Do not hesitate to ask questions if you are not sure about any problems. We are always ready to answer you.

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