Health Risks of Secondhand Smoke

No amount of secondhand smoke is safe

Young child being exposed to secondhand smoke
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In This Article

Secondhand smoke, also known as environmental tobacco smoke (ETS), occurs as a result of breathing in pollutants in the air from tobacco products. When non-smokers inhale secondhand smoke, it's termed involuntary or passive smoking. While much deserved attention gets put on the health risks of smoking itself, secondhand smoke exposure can also cause very serious consequences including respiratory conditions, heart disease, and cancer.

There are no safe levels of secondhand smoke. It's important that you consider your surroundings to protect your health.

What's in Secondhand Smoke?

Secondhand smoke is a combination of two types of smoke: mainstream smoke, which is actually exhaled from the person who is smoking, and sidestream smoke, which is emitted from the end of a burning cigarette, cigar, pipe, or tobacco burning in a hookah.

According to the American Lung Association, smoke emitted from tobacco contains about 7,000 toxic chemicals; of these, hundreds are known toxins and 69 are known to be linked to cancer (carcinogenic). Both types of secondhand smoke contain the same toxic carcinogens, but sidestream smoke is more concentrated and contains smaller particles, which make their way into the lungs easier.

Each time someone lights up a cigarette, poisonous chemicals such as benzene, formaldehyde, vinyl chloride, arsenic ammonia, hydrogen cyanide, and carbon monoxide are released into the air. While smokers inhale these poisonous substances directly, nonsmokers do so in an indirect manner as a result of secondhand smoke.


Although everyone exposed to secondhand smoke is at risk, certain groups of people are at higher risk for developing severe problems from secondhand smoke. This includes unborn babies and newborns, children and teens, and people with asthma or other respiratory conditions, including those with COPD.

The Surgeon General and the Environmental Protection Agency (EPA) recommend that no one smoke when young people are present, and new laws have been formed to protect adults from the harmful effects of ETS, too, especially in the workplace.


Secondhand smoke is a major respiratory irritant. It may cause the following issues:

Respiratory Conditions
Secondhand smoke can cause or worsen chronic obstructive pulmonary disease (COPD) and asthma. Adults with COPD are particularly at risk when exposed to secondhand smoke, often developing a worsening of symptoms, including increased shortness of breath, cough, and mucus production.

Moreover, secondhand smoke acts as a major trigger for asthma. Just the odor of smoke on clothing or skin is enough to trigger symptoms.

For people with COPD and other lung conditions, secondhand smoke exposure can prompt an exacerbation of symptoms, which can lead to hospitalization.

Cardiovascular Disease
People who don't smoke are at an increased risk for high blood pressure and cardiovascular disease when they are exposed to secondhand smoke

Secondhand smoke can also cause lung cancer in people who don't smoke. Declared by the EPA as a human lung carcinogen, secondhand smoke is responsible for approximately 3,400 lung cancer deaths annually in nonsmokers in the U.S., and has been associated with stroke and hardening of the arteries.

According to the American Cancer Society, there's some evidence that secondhand smoke can also result in cancers of the following:

  • Brain
  • Breast
  • Bladder
  • Larynx (voice box)
  • Pharynx (throat)
  • Rectum
  • Sinus cavity
  • Stomach

Babies and Newborns

When a woman smokes during pregnancy, the unborn child receives less oxygen and develops an increased level of carbon monoxide in his or her bloodstream. This can lead to a higher incidence of miscarriage, premature birth, stillbirth, and sudden infant death syndrome (SIDS).

Babies exposed to cigarette smoke in the womb are also at risk for low birth weight and other complications. Additionally, there is a definite connection between smoking during pregnancy and SIDS. In fact, infants of mothers who smoke are more than two times as likely to die of SIDS than children of non-smokers.

Children and Teens

While there is good news that exposure to secondhand smoke is declining in the past decade, more than 35% of American children (23 million) are still exposed to secondhand smoke, according to the American Lung Association.

Because children have smaller airways, they are more sensitive to secondhand smoke than adults. When a child is exposed to secondhand smoke, his or her ability to breathe becomes impaired, as the airways become inflamed and filled with mucus. This leaves them more susceptible to respiratory symptoms such as coughing and wheezing and often leads to respiratory infection.

Secondhand smoke is associated with 7,500 to 15,000 hospitalizations of infants and toddlers annually and leads to more than 430 deaths from sudden infant death syndrome (SIDS) each year. Furthermore, because secondhand smoke irritates the airways of the lungs, it is a powerful trigger for children who have asthma, contributing to tens of thousands of new cases each year in children. It is also known to aggravate asthma symptoms in more than 202,000 children with asthma annually. Secondhand smoke may also cause fluid buildup in the middle ear, resulting in 790,000 doctor's office visits every year.

Children and teens of parents who smoke not only develop more frequent respiratory infections but have more difficulty recovering from them. Secondhand smoke is also known to be associated with pneumonia and bronchitis in children.

What About Vaping Smoke?

E-cigarette emissions are aerosols that can contain nicotine and highly toxic compounds called volatile organic compounds (VOCs), such as benzene, acetaldehyde, formaldehyde, as well as tobacco-specific nitrosamines. This, like cigarette smoke, is harmful—particularly to children and to adolescents' brain development, according to the U.S. Surgeon General.

Secondhand Smoke-Related Deaths 

The American Lung Association estimates that secondhand smoke is responsible for more than 41,000 deaths each year.

Even brief exposure to secondhand smoke can trigger a heart attack or an exacerbation of a wide range of negative health consequences. Additionally, exposure causes disease and premature death in both children and adults who don't smoke.

Secondhand smoke is known to cause approximately 7,330 deaths from lung cancer and 33,950 deaths from heart disease every year, according to the American Lung Association.

How to Prevent Exposure

The only true way to reduce exposure to secondhand smoke is by prohibiting smoking in any indoor space, including homes, public buildings, offices, and cars. Separating smokers from nonsmokers and ventilating buildings does little to limit exposure.

It is extremely important if you have any type of respiratory condition, including asthma and COPD, that you not only quit smoking but avoid secondhand smoke as well. The following steps can be taken in an effort to prevent exposure:

  • Never allow anyone to smoke inside your home, office, or car.
  • Explain your “smoke-free home” policy to everyone who visits. People who really care about you will respect and support your house rules.
  • Discourage smoking behavior in your home by removing all ashtrays.
  • Advise guests and family members, if they must, to smoke outside, away from open windows or doors.
  • Do not frequent places where people are smoking. If you must be in an area where public smoking is taking place, sit or stand in a well-ventilated, non-smoking section of that area.
  • If family members smoke, suggest that they quit.
  • Join, or suggest your loved one join a stop-smoking support group. 

If you or a loved one is having difficulty quitting, talk to your healthcare team about getting help. Nicotine replacement therapy and other medications are available and can increase your chances of successfully quitting.

While Traveling

Although many cities and communities have made great strides in banning smoking from public buildings, restaurants, and parks, there are still parts of the world where smoking is allowed everywhere—even on flights.

The best way to prevent exposure to secondhand smoke is to plan ahead and to advocate for yourself:

  • Request a non-smoking room: Whether you are booking a hotel room or a cabin on a cruise ship, always request a non-smoking room; never assume it's the norm in the culture where you're traveling. In addition, make your sensitivity to cigarette smoke known at the time of your reservation and at check-in. The hotel or ship’s cleaning crew can use a high-powered air filter system to clean the air in your room prior to your arrival if smoking has previously been allowed in the room.
  • Use a smoke filter mask: If you can’t avoid secondhand smoke in public places, avoid breathing it in by covering your mouth in smoky areas. A filter mask, can block up to 95% of air particles and is a handy and lightweight way to prevent exposure.
  • Aim to keep smoke off your clothing: If you can’t stay in a smoke-free hotel, keep your clothes stored in a garment bag or suitcase to keep them from absorbing cigarette smoke. If the dresser in the hotel smells of cigarette smoke, the best thing to do is to not use it and keep your clothes in your suitcase. Likewise, if you spend time in smoke-filled areas, causing your clothes to smell, store them in a separate bag away from the rest of your attire.

A Word From Verywell

Although smoke-free ordinances exist in many cities across the country, more needs to be done to protect the health of all people, especially children. Continuing education in our schools and in the workplace can help shed light on this sensitive subject. Every individual is entitled to breathe clean, fresh air, free from the harmful effects of secondhand smoke.

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