This is a response to a question about second hand smoke. This smoke contains about 4,000 substances, more than 40 of which are known to cause cancer in humans or animals. Many others are known irritants. This exposure can damage the developing lungs of young children. Studies have shown that children exposed to secondhand smoke are more likely to have diminished lung function, infections, coughing, wheezing, and increased mucous production.
Asthmatic children are especially at risk.
Healthy children are adversely affected by secondhand smoke as well. The EPA estimates that passive smoking is responsible for between 150,000 and 300,000 lower respiratory tract infections in children less than 18 months old. Exposure to smoke may lead to a buildup of fluid in the middle ear, which in turn contributes to the development of childhood middle ear infection. A study from the Alberta Children's Hospital demonstrated a connection between exposure to cigarette smoke in the home and increased risk of middle ear infection. Parents can decrease their children's exposure to secondhand smoke by simply not smoking.