It’s common knowledge that smoking increases lung cancer risk, but what about indirect exposure to cigarettes? The World Health Organization reports that about one-third of adults worldwide are regularly exposed to cigarette smoke despite not smoking themselves. Secondhand smoke exposure (inhaling smoky air when people smoke nearby) is a known risk factor for lung cancer. However, the effects of thirdhand smoke exposure from cigarette residue are not as well-established.

If you live or work with a smoker who doesn’t smoke around you, you may still be at heightened risk for lung cancer. Here’s a deeper explanation of where thirdhand smoke may be lurking and how you can lessen its impact on you and your loved ones.

What Is Thirdhand Smoke?

After cigarette smoke has been cleared from the air, nicotine and other toxins from cigarettes can linger in smokers’ homes on surfaces such as clothing, furniture, and carpets. This “thirdhand smoke” builds up with repeated smoking sessions and can’t always be cleaned away. Unlike secondhand smoke, thirdhand smoke may linger for weeks or months after a cigarette has been put out.

Cigarette smoke contains over 60 carcinogens (cancer-causing substances) and thousands of chemicals. Furthermore, chemicals from cigarette smoke may change over time, aging and potentially becoming more toxic. As thirdhand smoke gets absorbed back into the air, it may form additional pollutants with unknown side effects. For example, formaldehyde and other carcinogens are produced when nicotine combines with ozone, a gas present in the air.

In addition to nicotine, thirdhand smoke contains polycyclic aromatic hydrocarbons and tobacco-specific nitrosamines. Heavy metals like arsenic, cyanide, and lead may also be found in thirdhand smoke. As these compounds combine with substances in walls or carpeting, new toxins may be formed. Thirdhand smoke can even be detected in dust particles, making it especially difficult to measure or avoid.

Health Effects of Thirdhand Smoke

The main way people are exposed to thirdhand smoke is by absorbing chemicals through the skin or by accidentally swallowing them. The skin can easily absorb nicotine from the surrounding air or surfaces. Using specialized wipes to detect nicotine levels on fingers and hands is one method researchers use to assess thirdhand smoke. Levels are notably higher in people who smoke, in people who recently quit smoking, and in the young children of smokers.

Studies show that living with someone who smokes increases a person’s risk of poor health. When babies are exposed to tobacco smoke (during infancy or in the womb), they are at greater risk for serious health problems, including respiratory infections, asthma, and sudden infant death syndrome. However, it can be almost impossible to distinguish whether some risks are due to secondhand or thirdhand smoke.

Most health officials view thirdhand smoke as an underestimated public health hazard with the potential to impact babies and children the most. In addition to having carcinogens that are known to cause cancer, thirdhand smoke contains pollutants that can damage DNA. This can produce harmful gene mutations that are associated with an increased risk of cancer, including lung cancer.

How To Lower Your Risk

It’s not always possible to avoid items that contain thirdhand smoke. For instance, if you live in an apartment that was previously smoked in, you may not know about the pollution that’s been left in your home. Research shows that even in homes where people only smoke outside, children of smokers have a five to seven times higher exposure to nicotine than in completely smoke-free homes.

Before moving into an apartment, ask your landlord about past smoking policies and the procedures used to clean units between tenants. Just because the space doesn’t smell like smoke doesn’t mean you’re not at risk. In fact, some dangerous compounds in thirdhand smoke don’t smell at all.

To create a smoke-free environment in your home:

• Clean the ventilation systems — Be sure to install new filters.
• Remove carpeting and padding — Replace them with new materials after floors have been washed.
• Repaint walls — Add at least two coats of fresh paint.
• Wash walls, ceilings, and floors — Wash multiple times with hot water and detergent. Don’t forget to wear gloves.

If you smoke or live with someone who does, you can take extra precautions to reduce thirdhand smoke. Ideally, smokers should avoid smoking indoors and always wash their hands after reentering the home.

Keeping up with house cleaning won’t completely get rid of thirdhand smoke, but it helps. Since dust is a significant source of thirdhand smoke, vacuuming and dusting frequently are essential. Make a habit of wiping high-traffic indoor surfaces often, including doorknobs, tabletops, and cabinets. Be sure to throw your window treatments and bedding in the wash regularly as well.

Quitting smoking is the best thing you can do for yourself and those around you. The Centers for Disease Control and Prevention (CDC) has tools and resources to help you quit, including tips from former smokers and a free quitline for support over the phone. Quitting smoking often requires more than one attempt, so don’t be afraid to try again even if you’ve tried and failed in the past.

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer and their loved ones. On MyLungCancerTeam, more than 6,200 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

How has thirdhand smoke affected you or your family? Share your experience in the comments below, or start a conversation by posting on your Activities page.