Secondhand smoke refers to the fumes that are emitted when smokers use:

  • cigarettes
  • pipes
  • cigars
  • other tobacco products

Firsthand smoking and secondhand smoke both cause serious health effects. While directly smoking is worse, the two have similar adverse health effects.

Secondhand smoke is also called:

  • side-stream smoke
  • environmental smoke
  • passive smoke
  • involuntary smoke

Nonsmokers who inhale secondhand smoke are affected by chemicals contained in the smoke. According to the World Health Organization (WHO), there are over 4,000 chemicals found in tobacco smoke. In all, 50 are cancerous. Over 250 are harmful in other ways.

Fluids, such as blood and urine, in nonsmokers might test positive for nicotine, carbon monoxide, and formaldehyde. The longer you’re exposed to secondhand smoke, the greater the risk you are of inhaling these toxic chemicals.

Exposure to secondhand smoke occurs anywhere someone might be smoking. These places can include:

  • bars
  • cars
  • homes
  • parties
  • recreational areas
  • restaurants
  • workplaces

As the public learns more about the harmful effects of smoking, overall smoking rates continue to go down among teens and adults. However, according to the Centers for Disease Control and Prevention (CDC), 58 million American nonsmokers are exposed to secondhand smoke.

Overall, WHO estimates that at least 890,000 premature deaths per year are related to secondhand smoke worldwide. This is a serious health concern that can affect both adults and children who are exposed to secondhand smoke. The only way to eliminate such risks is to stay away from tobacco smoke entirely.

Effects in adults

Secondhand smoke exposure is common in adults. You might work with others who smoke around you, or you might be exposed during social or recreational events. You might live with a family member who smokes.

In adults, secondhand smoke can cause:

Cardiovascular diseases

Nonsmokers who are exposed to secondhand smoke are at a 25 to 30 percent greater risk of heart disease, according to the American Heart Association. Also, smoke exposure can make preexisting cases of high blood pressure worse.

Respiratory diseases

Adults may develop asthma and have frequent respiratory illnesses. If you already have asthma, then being around tobacco smoke might make your symptoms worse.

Lung cancer

Secondhand smoke may even cause lung cancer in adults who don’t directly smoke tobacco products. Living with someone who smokes may increase your individual lung cancer risk by as much as 30 percent, according to the National Cancer Institute. In the United States, the CDC estimates 7,300 deaths from lung cancer in nonsmokers per year.

Other cancers

Among the possibilities include breast cancer, leukemia, and lymphoma. Cancers of the sinus cavity are also possible.

Effects in children

While regular secondhand smoke exposure can lead to a variety of health issues in adults, children are even more vulnerable to the effects of being around tobacco smoke. This is because their bodies and organs are still in developmental stages.

The CDC also states that black children are more likely to be exposed to cigarette smoke. Children don’t have a say when it comes to being around cigarette smoke. This makes decreasing associated risks even more challenging.

The health consequences of secondhand smoke in children include:

  • Lung health effects. This includes delayed lung development and asthma.
  • Respiratory infections. Children exposed to secondhand smoke have more frequent infections. Pneumonia and bronchitis are the most common.
  • Ear infections. These often occur in the middle ear and are frequent in nature.
  • Worsening asthma symptoms, such as coughing and wheezing. Children with asthma might also be privy to asthma attacks from frequent secondhand smoke exposure.
  • Constant cold or asthma-like symptoms. These include coughing, wheezing, and shortness of breath, as well as sneezing and runny nose.
  • Brain tumors. These might develop later in life, too.

Infants are even more vulnerable to the effects of secondhand smoke because it can cause sudden infant death syndrome (SIDS). Pregnant women who are exposed to secondhand smoke may also deliver children with low birth weights.

The WHO estimates that of all the reported secondhand smoke-related deaths, 28 percent of these fatalities are children. As a parent, one of the best ways you can prevent secondhand smoke exposure for your child is to quit smoking yourself.

The bottom line

Given the numerous adverse health effects of secondhand smoke, avoidance is increasingly being viewed as a human right. This is why many states have enacted laws prohibiting smoke in common areas, such as restaurants, outside of schools and hospitals, and on playgrounds. To date, the WHO says about 18 percent of people worldwide are protected by such laws.

Despite the enactment of no-smoking laws, the only way to fully protect nonsmokers from secondhand smoke is smoking cessation. If you live in a multiunit house, cigarette smoke can travel between rooms and apartments. Being outside in an open area, or opening windows around an indoor smoker, does little to stop the effects of secondhand smoke. If you’re around tobacco smoke, the only way you can fully eliminate exposure is by leaving the affected place entirely.

The problem according to the CDC, though, is that most secondhand smoke exposure takes place inside homes and job sites. In such cases, it’s nearly impossible to avoid secondhand smoke as a nonsmoker. This is especially true for children whose parents smoke inside houses and cars. Quitting smoking is the best way to protect nonsmokers from secondhand smoke.