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Protect Children from Third Hand Smoke Exposure

How tobacco smoke lives and lingers long after the smoke has "supposedly" cleared

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Studies have shown that when just one cigarette was smoked in a bedroom with the door closed, it took two hours for particulates in the air to return to below the threshold for harm. Figure: Ott et al. 2003. J. Air & Waste Manage. Assoc.

Many people today are aware of the dangers of second hand smoke—the smoke that comes off a lit cigarette or is exhaled by a smoker. That's why there have been increased restrictions on indoor smoking, and why many smokers today go outside to smoke. Now medical researchers are asking what happens after second hand smoke has cleared? Could other dangers exist beyond the visible plumes a lit cigarette emits? Studies have shown that when just one cigarette was smoked in a bedroom with the door closed, it took two hours for particulates in the air to return to below the threshold for harm.

What is third hand smoke?

What happens when second hand smoke collects on our clothes, or in the car seats, furniture, carpets, and even the wallboard that surround us? The contamination that persists after second hand smoke has dissipated is called third hand smoke (THS).

Researchers have identified significant amounts of toxins from third hand smoke in homes and cars of smokers even months after no smoking has occurred. Residual pollutants remain on surfaces and in dust; they re-emit as nicotine gas or as ultrafine particles; and they can collect in textiles and other materials to create a reservoir that emits gas over time. These pollutants can also react with other compounds in the environment, like ozone, to create secondary pollutants.

We know these residual toxins exist, but researchers haven't yet established what constitutes a harmful dose, partly because it is difficult to isolate which negative health effects are caused specifically by third hand rather than second hand smoke exposure.

Children are most vulnerable to third hand smoke exposure

Because they crawl on carpets and furniture and put things in their mouths, children are most vulnerable to third hand smoke. They have smaller body mass, breathe faster, have less-developed defenses against environmental pollutants, and spend more time indoors.

Susanne E. Tanski, MD, MPH, FAAP, a Norris Cotton Cancer Center researcher and Dartmouth-Hitchcock pediatrician who studies the effect of third hand smoke on children, noticed in her practice that the smoking parents of her patients were often unaware of third hand smoke exposure. She wanted to help them learn about reducing this exposure, and to support them if they wanted to quit smoking.

Tanski notes that it was nonsmoking flight attendants who first raised awareness about the health hazards of secondhand smoke when they successfully brought a class action law suit against the tobacco industry in 1997. "Kids are a lot like flight attendants," she said. "They have no choice and no voice with regard to their own exposure: adults expose kids to smoke."

"We really need to have 100% smoke free homes and cars," Tanski explained at a recent NCCC Grand Rounds presentation. "You can't smoke in one room with the door closed and say that whole space is safe."

Even when parents understand the dangers of second hand smoke in the home, many think it is safe to smoke in a car if children aren't in it. "For many smokers the car is the last place they can smoke," she said.

But smoking in the car creates an especially intense environment for third hand smoke exposure. The nicotine can combine with nitrous acid from exhaust to create cancer-causing tobacco-specific nitrosamines (TSNAs) that settle into the dust on the dashboard, seats, and carpets. And these TSNA's can be absorbed through the skin—when you open a glove compartment or dust off the dash with your hand.

Help smokers stop exposing their loved ones to third hand smoke

The only way to protect nonsmoking family members completely is for all family smokers to quit completely, Tanski says, but there are things you can do if this is not a possibility:

  • Create (and enforce) 100% smoke-free home and car rules
  • Be specific about what these rules mean: It does not mean smoking in a room with the door closed, near an exhaust fan, or in the car with the windows open.
  • Help those who are not yet able to quit by suggesting support tools like smoking cessation programs, or using nicotine replacement therapy as a way to maintain a smoke free home and car.

February 04, 2013