San Francisco is set to become the first U.S. city to ban the sale of e-cigarettes. City officials unanimously voted in favor of the ban Tuesday, and Mayor London Breed has indicated she will sign off on it. The ban also applies to flavored tobacco products. Proponents of the bill say that e-cigarettes have not been properly assessed by the Food and Drug Administration for safety. The spread of vaping among young people in recent years has raised concerns about the long-term health effects of the products. Opponents of the bill say the ban could cause people to turn back to conventional cigarettes. Juul, the most popular producer of e-cigarettes, is headquartered in San Francisco.