888.552.6760 SCHEDULE A CONSULTATION

The information on this page was reviewed and approved by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on May 21, 2021.

Secondhand and thirdhand smoke and cancer

Smoking tobacco is the leading cause of cancer throughout the world. But smoking isn’t just harmful to those who light up. Secondhand smoke, which is the smoke left in the air from cigarettes, cigars, pipes or other forms of tobacco, may also lead to cancer and premature death in both children and adults. Researchers are also looking into something called “thirdhand” smoke—the remnants of tobacco smoke that get caught in fabrics and land on hard surfaces.

How does secondhand smoke cause cancer?

Secondhand smoke causes cancer in much the same way as firsthand or direct tobacco smoking. When someone lights up a cigarette, cigar or tobacco pipe, smoke is released into the air from both the burning paper and tobacco itself (sidestream smoke) and from the breath that the smoker exhales (mainstream smoke). Both of these types of smoke contain substances that are harmful to breathe in, including the following carcinogens, or cancer-causing agents:

  • 1,3-butadiene
  • Benzene
  • Benzo[α]pyrene
  • Cadmium
  • Formaldehyde
  • Tobacco-specific nitrosamines

Exposure to carcinogens may cause cell mutations that lead to cancer. Like all tobacco smoke, secondhand smoke is associated with lung cancer. In the United States, it leads to 7,333 deaths from lung cancer per year among non-smokers and 33,951 deaths from heart disease per year, according to the U.S. Centers for Disease Control and Prevention. Research also suggests that it may be linked to breast, nasal and throat cancers in adults. It has also been linked to stroke.

Children are also harmed by secondhand smoke, starting in the womb.

  • Exposure to secondhand smoke by pregnant women has been linked to lower weights of their babies at birth.
  • Childhood cancers such as leukemia, lymphoma and brain cancers may be linked to secondhand smoke.
  • Secondhand smoke is also known to worsen asthma and increase the risk of ear infections, colds, bronchitis, pneumonia and SIDS.

How does thirdhand smoke cause cancer?

“Thirdhand” smoke isn’t actually smoke, but rather what smoke leaves behind. Thirdhand smoke refers to the residual particles from tobacco smoke that settle on surfaces or in fabric, including floors, carpets, furniture and clothing. Research into whether thirdhand smoke may cause cancer is more limited than research into secondhand smoke. Still, some of the same carcinogens found in first and secondhand smoke have also been found in samples of dust taken from the homes of people who smoke, suggesting that inhaling or swallowing that dust may be harmful.

How to stay safe from secondhand and thirdhand smoke

Exposure to secondhand and thirdhand smoke exists whenever indoor tobacco smoking is taking place. Keeping yourself and your family away from those situations is the only way to reduce the risk of cancer and other health problems posed by secondhand and thirdhand smoke. There is no safe level of exposure to secondhand smoke (information about thirdhand smoke isn’t yet known).

To avoid secondhand and thirdhand smoke:

  • Don’t allow smoking in your home, car or place of business.
  • Choose restaurants, bars and other locations that are smoke-free if your state allows indoor smoking in public areas.

If you’re inside where people are smoking, there isn’t anything you can do to protect yourself or others from secondhand or thirdhand smoke.

  • Limiting smoking to one part of the home, opening the windows or using a fan won’t protect you from secondhand and thirdhand smoke.
  • Similarly, rolling down the window while someone smokes in your car won’t keep you safe from secondhand smoke either.

Public health measures introduced over the past few decades have worked to curb indoor smoking and reduce or eliminate workplace exposure to secondhand smoke. Federal law prohibits smoking on public transportation and in federal buildings. Recently, smoking inside public housing was banned. State laws about smoking vary across the country, but about half of states have banned smoking from places such as hospitals, malls, movie theaters, restaurants and bars. Authorities have also started banning smoking in open spaces such as parks and beaches in some cities and states.