Secondhand Smoke and Cancer Risk

Secondhand smoke is the tobacco smoke that people breathe in when they are near someone who is smoking. You do not have to smoke to be exposed to it.

This smoke is not harmless. It contains many of the same cancer-causing chemicals as the smoke a smoker breathes in. Because of this, secondhand smoke can cause lung cancer in people who have never smoked.

Experts agree there is no safe level of secondhand smoke.

Secondhand smoke comes from two sources:

• The smoke that drifts off the burning end of a cigarette, cigar, or pipe
• The smoke that a smoker breathes out into the air

When these mix, they fill the air around a smoker. Anyone nearby breathes them in. This is why secondhand smoke is sometimes called "passive smoking" or "involuntary smoking."

Tobacco smoke contains thousands of chemicals. Many of them are known to cause cancer. These same chemicals are present in secondhand smoke.

When a nonsmoker breathes secondhand smoke, those chemicals enter their body. Over time, they can damage cells in the lungs and lead to cancer.

Secondhand smoke is known to cause lung cancer in adults who do not smoke. It is also linked to other serious health problems, such as heart disease and breathing problems.

Breathing someone else's smoke carries real risk.

You might think a little smoke here and there is harmless. But that is not what the science shows.

Experts have concluded that there is no safe level of secondhand smoke exposure. Even brief exposure can harm the body.

Common myths do not hold up:

• Opening a window does not clear the harmful chemicals.
• A fan does not make the air safe.
• Smoking in another room still lets smoke travel through the home.

The only way to fully protect nonsmokers is to keep spaces completely smoke-free.

Secondhand smoke can harm anyone who breathes it. Some groups are especially vulnerable.

Children are at higher risk because their bodies are still growing and they breathe faster than adults. Secondhand smoke can cause serious health problems in children, including breathing illnesses.

People with existing heart or lung conditions may also feel the effects more strongly. And unborn babies can be affected when a pregnant person is exposed to smoke.

The best protection is to keep smoke out of the places you spend time.

Helpful steps include:

• Make your home completely smoke-free.
• Keep your car smoke-free, even with windows down.
• Avoid indoor places where smoking is allowed.
• Support smoke-free rules in shared spaces.

If someone you live with smokes, encouraging and supporting them to quit helps everyone. Quitting protects the smoker and clears the air for the whole household.

Your healthcare team can share resources and help connect a loved one with quit support.

Sometimes you can still smell smoke long after someone has finished a cigarette. This lingering residue settles onto surfaces like walls, furniture, carpets, and clothing.

Researchers are still studying this residue and its effects. But the presence of a stale smoke smell is a reminder that smoke leaves traces behind. The most reliable way to keep these traces out of your living space is to keep smoking out of it entirely.

This is another reason a fully smoke-free home is the goal, rather than trying to smoke in just one room or near a window.

Keeping spaces smoke-free is not only about avoiding harm. It also creates a healthier environment for everyone.

When a home or car is smoke-free:

• Children breathe cleaner air.
• People with asthma or heart conditions are better protected.
• The person who smokes may find it easier to cut back or quit.

Setting a smoke-free rule can feel like a big change, but it is one of the clearest ways to protect the people you care about. Your healthcare team can offer tips for making the change and can help a household member who wants to quit.