What Is Thirdhand Smoke?

Even if you don’t smoke, you may be exposed to the harmful effects of cigarettes, cigars, pipes, and other burning tobacco products that other people use.

When you inhale smoke that’s in the environment—known as secondhand smoke—you’re breathing in the same toxic chemicals that smokers do, including nicotine.

But there’s also something called thirdhand smoke that can pose health risks. Thirdhand smoke is the residue from secondhand smoke that settles on furniture, walls, carpeting, clothing, and other surfaces after someone has smoked in that area. Thirdhand smoke, which is made up of the gases and particles that settle on surfaces after the smoke dissipates, is sometimes called residual tobacco smoke.

Spaces that contain thirdhand smoke may smell like someone has smoked there for weeks or even months. The deposited gases and particles from thirdhand smoke may combine with gases in the air, forming cancer-causing compounds that can become progressively hazardous over time. People may inhale these off-gassing chemicals from thirdhand smoke. Long-term exposure to thirdhand smoke pollutants has been shown to damage human cells and DNA and may be associated with asthma and cancer.

People can also be exposed to thirdhand smoke by touching contaminated surfaces, and harmful chemicals can be absorbed into the skin.

Yale researchers have found that thirdhand smoke also settles on the clothing or bodies of smokers or people who are exposed to secondhand smoke. Their research shows that thirdhand smoke travels with people, and some of its toxic chemicals are released in new locations, such as movie theaters. Because of this, thirdhand smoke can be present in areas where people didn’t smoke and where secondhand smoke was not present before. It can also persist for years after exposure.

Their work also takes a deep dive into the chemical composition of thirdhand smoke, showing the diverse range of compounds present in thirdhand smoke, depending on whether it is from particles settling on surfaces or the inside of smokers’ lungs. This collection of work by the Gentner group and PhD graduate Roger Sheu is important, says Yale’s Drew R. Gentner, PhD, an associate professor of Chemical & Environmental Engineering, “since it shows the remarkable chemical diversity of thirdhand tobacco smoke and how its chemical composition evolves over time; it also demonstrates how the chemical markers tobacco have been observed in a range of environments, including the homes of smokers who only smoke outside the residence.”

Below, we discuss thirdhand smoke and how to minimize your exposure.

Long after the air clears from a smoking product, toxic chemicals, and particles can remain on surrounding surfaces—sticking to walls, furniture, carpet, clothing, hair, and even pet fur. Children are particularly vulnerable to thirdhand smoke because they may crawl on the floor, touch many surfaces, and place objects in their mouths. What’s more, children who live in apartments reportedly show a higher level of exposure to tobacco chemicals.

Although electronic, or e-cigarettes, do not burn tobacco, the heated fluid containing nicotine and chemicals releases a vapor that creates “smoke” and can stick to clothes, furniture, and other surfaces. Nicotine residue can remain on indoor surfaces for days after someone has used an e-cigarette, also known as vaping.

Thirdhand smoke can be difficult to remove from polluted locations, which can include sheetrock, drywall, floors, and ceilings. It’s important to note that common cleaning methods will not remove thirdhand smoke.

Research is limited on the best way to remove it, but here are some tips:

• Vacuum frequently and thoroughly with a HEPA (high-efficiency particulate air) filter, and regularly wipe, wash, or scrub surfaces with acidic (white household vinegar) and alkaline (such as Simple Green®) solutions. Pay attention to hard-to-see areas, such as the undersides of furniture, inside cabinets, and walls covered by hangings.

• Wash polluted blankets, pillows, clothes, and toys in the washing machine. It may require multiple washes. Use a dishwasher for tableware and plastic toys; multiple washes may also be needed.
• If certain items, such as HVAC ducts or mattresses, cannot be cleaned, replace them, if possible.

Keep in mind that ridding a room of the stale tobacco smell does not mean the pollutants have been removed.

For more advice on cleaning, including how to clean heavily polluted walls, ceilings, and floors, visit the Thirdhand Smoke Resource Center.