The Dangers of Secondhand Smoke

First published September 2014
Updated November 2025

Smoking is expensive, addictive and, most importantly, deadly. Unfortunately, many adults willingly accept those consequences. But as parents and caregivers, we would never physically hand our children cigarettes with their dinner, during a car ride or any other time.

Yet every day, millions of children are exposed to secondhand smoke without a thought for their health. Kids are also often exposed to “thirdhand” smoke, which comes from toxins that build up over time on surfaces exposed to smoke, including upholstery, carpets, clothing and hair. These layers of toxins can become cancer-causing substances.

What Are Secondhand and Thirdhand Smoke?

• Secondhand smoke is the combination of smoke exhaled by a smoker and the smoke that comes from a burning cigarette, cigar, or pipe.
• Thirdhand smoke refers to the toxic residue left behind on clothing, furniture, carpets, and hair after tobacco has been used. These chemicals build up over time and can break down into cancer-causing substances.

Why Smoke Exposure Is So Dangerous for Children

Children’s lungs and immune systems are still developing, making them especially vulnerable to the effects of tobacco smoke. Here’s what we know:

• There is no safe level of smoke exposure.
• Smoke in a car can reach levels comparable to what a firefighter experiences during 4–8 hours of battling a wildfire.
• Cracking a car window while smoking still exposes kids to 13 times the level of outdoor smoke.
• Smoke toxins can linger for days, even after the smoker has left the space.
• Kids who grow up around smokers are more likely to start smoking themselves.
• Exposure increases the risk of lung cancer by 20–30% in adults who don’t smoke.
• Children exposed to smoke have more frequent colds, ear infections, and bronchitis.
• Among children with asthma seen in emergency departments, 40% have at least one parent who smokes.
• Secondhand smoke can stunt lung growth in children with cystic fibrosis.
• The safety of e-cigarette vapor has not been fully tested—treat it as you would any other tobacco product.

Quitting smoking is incredibly challenging—but you can still make immediate changes that significantly reduce your child’s exposure.

• Never smoke inside your home or car.
• If you do smoke, use a “smoking jacket” with a hood to keep smoke residue off your clothing and hair, and leave it outside after use.
• Wash your hands and face after smoking.
• Keep e-cigarette liquids and cartridges out of reach. These contain concentrated nicotine, which can poison a child if swallowed.
• Encourage family and friends to join you in creating a smoke-free environment.
• Talk with your health care provider about smoking cessation tools and support programs.
• Advocate for stronger protections: call or email your state legislators to support laws banning smoking in cars when children are present. Seven states already have these laws—Ohio and others should follow.

You’re Not Alone

About one in five adults in Ohio still smoke, but help is available. Nationwide Children’s Hospital offers resources to help families quit smoking and reduce children’s exposure to harmful substances. Talk to your pediatrician for more information on quitting strategies and family safety.

Protecting kids from smoke exposure is one of the most powerful ways to give them a healthy start in life.