Final answer:
Secondhand smoke is a significant risk factor for lung cancer in non-smokers, but other factors like radon, asbestos, and air pollutants also contribute. Exposure to secondhand smoke increases the risk for non-smokers, but it is not the number one cause of lung cancer among non-smokers.
Step-by-step explanation:
The statement - The number one cause of lung cancer among nonsmokers is secondhand smoke - is false. While secondhand smoke is certainly a significant risk factor and is carcinogenic, other environmental factors such as radon gas, asbestos, and other air pollutants also contribute to lung cancer in nonsmokers. Tobacco smoke contains over 50 known carcinogens and smoking accounts for 85-90 percent of lung cancer cases. However, exposure to secondhand smoke can increase the risk of developing lung cancer by up to 30 percent in nonsmokers, compared to those not regularly exposed. Children are particularly vulnerable, facing a higher risk of respiratory infections, ear infections, sudden infant death syndrome (SIDS), and worsening asthma symptoms due to secondhand smoke exposure.