According to the Centers for Disease Control and Prevention, all secondhand smoke is potentially dangerous, whether from the end of a cigarette or the exhalation of a smoker. Smoke presents health risks for bystanders of all ages. Children are especially at risk because they have a higher ratio of inhaled air to body weight than adults. Kids' physical and behavioral development can be severely impacted by regular contact with secondhand smoke.
Respiratory System Development
Babies' lungs are not fully developed at birth; they continue to develop as kids grow. Secondhand smoke can inhibit proper formation of the lungs and thus impair function, and many types of respiratory problems can appear. Kids can become burdened with chronic coughing, wheezing and excessive phlegm production. Smoke worsens the symptoms of kids with preexisting asthma, and some children develop new cases of asthma after being exposed to secondhand smoke. Those children miss school at a higher rate and need more prescription medication. In fact, asthma is the leading cause of hospitalization of American children, and secondhand smoke contributes to that.
Immune System Development
Secondhand smoke can interfere with the development of a child's immune system, making children less able to fight off infection. Respiratory illnesses such as pneumonia and bronchitis are common problems due to reduced lung function from smoke exposure. Poor immune system function also leads to an increased number of serious ear infections in many kids. In the most severe cases, this can result in hearing loss or require children to receive ear tube surgery.
Development of Cancer
Secondhand smoke can lead to lung cancer in nonsmoking adults. A 2006 study by researchers from the Laboratory of Human Carcinogenesis determined that children who are exposed to secondhand smoke are more likely to develop lung cancer as adults. In addition, some cases of breast cancer may be caused, in part, by secondhand smoke. During puberty, breast tissue is more susceptible to dangerous chemicals that cause cellular changes; this may eventually lead to cancer.
A 2013 research study from the University of Montreal followed the behavioral development of a group of children from 17 months old through fourth grade. Although many had been exposed to varying levels of secondhand smoke at home, some had not. The children who had the highest levels of exposure were more likely to self-report aggressive behavior. In addition, their fourth grade teachers rated them higher on scales of antisocial behavior.