How risky is secondhand smoke?

Secondhand smoke causes or contributes to serious health problems, including:

• Cancer. Secondhand smoke is a known risk factor for lung cancer.
• Heart disease. Exposure to secondhand smoke increases the risk of heart disease by about 25% to 30%.
• Chronic lung disease. Exposure to secondhand smoke even for a short time causes measurable decreases in lung function. This can lead to chronic lung disease.

Secondhand smoke poses additional risks for children, who are especially vulnerable to the effects of secondhand smoke. Problems include:

• Reduced birth weight. Exposure to secondhand smoke during pregnancy increases the risk of having a baby with a reduced birth weight.
• Sudden infant death syndrome (SIDS). Secondhand smoke exposure is believed to increase the risk of SIDS.
• Asthma and respiratory illness. Secondhand smoke exposure is linked with the increased risk — and severity — of childhood asthma and wheezing. Infants of parents who smoke are more likely to develop bronchitis and pneumonia during the first year of life.