Final answer:
Smoking cigarettes is the number one preventable cause of death in the world.
Step-by-step explanation:
The number one preventable cause of death in the world is smoking cigarettes. Smoking is the most significant cause of respiratory disease, cardiovascular disease, and cancer. Exposure to tobacco smoke by smoking or breathing air that contains tobacco smoke is the leading cause of preventable death worldwide. Regular smokers die about 10 years earlier than nonsmokers. According to the Centers for Disease Control and Prevention (CDC), tobacco use is the single most important preventable risk to human health in developed countries and an important cause of early death worldwide.