What are the Health Effects of Thirdhand Smoke?

Smoking is one of the worst yet preventable dangers to your health. According to the American Heart Association (AHA), cigarettes have more than 5,000 chemicals. Many of these are toxic. Examples include arsenic, formaldehyde, and tar — many chemicals that you would see in manufacturing and processing facilities. Over time, smoking increases your risk of cancer, heart disease, and premature death.

But avoiding exposure to thirdhand smoke as a nonsmoker can be a bit more challenging, especially if you have a family member who smokes. The fact is that thirdhand smoke left over from someone else who smokes affects everyone in your family of all ages.

There are multiple health effects of thirdhand smoke in children. In fact, according to the Mayo Clinic, children are the most vulnerable to such effects. This is because they’re more likely to touch surfaces and put objects near their noses and mouths.

Children exposed to thirdhand smoke at home are more likely to have:

• asthma
• ear infections
• frequent illnesses
• pneumonia

Additionally, children who grow up with parents who smoke are at an increased risk of smoking themselves.

Infants can also be affected by thirdhand smoke. One study suggests that smoke exposure is one of the biggest risk factors for sudden infant death syndrome (SIDS). The other large risk factor for SIDS is improper sleeping position.

Aside from the risk of SIDS, thirdhand smoke exposure sets infants up for some of the same health risks as older children, including frequent illnesses and respiratory problems.

While not as vulnerable as babies and growing children, adults aren’t immune from the effects of thirdhand smoke, either. You may be at a higher risk of cancer later in life from repeated exposure to cigarette toxins.

While lung cancer is the greatest risk, the AHA also notes that smoke exposure can lead to cancers of the:

• bladder
• cervix
• kidneys
• mouth
• pancreas
• throat

In the short-term, thirdhand smoke can lead to more illnesses and infections. You may also cough more than normal.

If you’re pregnant, thirdhand smoke exposure can also affect your unborn baby. Whether you breathe in or touch surfaces with chemical residue, you’re at risk of taking in toxins from the smoke into your bloodstream. This can then transfer over to the fetus.

A small study examined the effects of thirdhand smoke exposure on fetal rat lung tissue. It found that certain toxins in cigarette smoke adversely affected lung development.

A baby’s exposure to thirdhand smoke can also lead to respiratory illnesses after birth. According to the American Academy of Pediatrics, smoking during pregnancy also increases the risk of SIDS.

You could still be breathing chemical residue from tobacco smoke in indoor spaces where no one has smoked for years. This was the surprise finding of a study published in the journal Science Advances.

Researchers at Drexel University in Philadelphia found that chemicals left on clothing, furniture and other surfaces by tobacco smoke – known as thirdhand smoke — can become airborne and travel through a building's ventilation system.

The researchers measured the air composition in a non-smoking, unoccupied classroom over the course of a month. They initially wanted to see what happens to outdoor air particles when they come inside. But they kept noticing a chemical signature that was only indoors and not outdoors. They discovered it consisted of chemicals from thirdhand smoke — and made up 29 percent of the air mass in the room.

"We didn't expect this at all." says Peter DeCarlo, associate professor of environmental engineering and chemistry at Drexel and lead author on the study.

DeCarlo and his team looked into the mechanism that would allow compounds from tobacco smoke to end up in a room that hadn't allowed smoking in at least 20 to 25 years. What they discovered was that thirdhand smoke compounds were effectively hitching a ride on tiny particles in the air.

The classroom they studied happened to be 20 meters down the hall from a balcony where people would sneak out for an unauthorized smoke. The room was also located near an office space where several smokers worked; that space shares the same HVAC system as the classroom in question.

The researchers suspect the thirdhand smoke from these smokers made its way into the classroom and stuck to surfaces there. The compounds were then exposed to another chemical — possibly ammonia from people's breath or skin, or even cleaning products — and became gaseous again.

"The chemistry of this is very interesting," says Neal Benowitz, professor of medicine at the University of California, San Francisco and a leader of the California Consortium on Thirdhand Smoke. He says scientists have known for some time that the nicotine levels in walls and furniture can persist for years. "What this study shows is that thirdhand smoke moves around the room," he says.

The Drexel researchers suggest that after becoming gaseous again, smoke residue compounds can attach themselves to tiny air particles that come inside through a building's HVAC system. Once the chemicals attach themselves to the air particles, the building's air distribution carries those chemicals throughout the building, including to the classroom researchers studied.

All this means people could be unwittingly exposed to thirdhand smoke in higher volumes than previously thought — even in locations where smoking has been forbidden for years.

Benowitz added, secondhand smoke exposure is usually limited to the time a smoker is in the room — a matter of minutes.

"With thirdhand smoke, there is a constant source of exposure, day after day after day," he says.