Story highlights San Francisco Board of Supervisors votes unanimously to raise legal smoking age to 21

Legal smoking age is 18 in majority of the U.S.

(CNN) Beginning June 1, anyone looking to purchase tobacco products in San Francisco must be at least 21 -- not 18, the legal age in the majority of the country.

The San Francisco Board of Supervisors unanimously approved the measure on Tuesday, according to CNN affiliate KPIX . With this new legislation, San Francisco joins Boston, New York and more than 100 other U.S. cities in raising the minimum age to buy cigarettes, e-cigarettes and other tobacco products. On January 1, Hawaii became the first U.S. state to raise its smoking age to 21.

Why is this so important?

From a health perspective, teenagers -- especially between ages 15 and 17 -- are most vulnerable to addiction, at a time when their brains are still developing, according to a report released last year by the Institute of Medicine . Even though most middle school and high school students in the United States have never used tobacco themselves, 48% of them report being exposed to secondhand smoke, according to a recent study conducted by the Centers for Disease Control and Prevention

The American Academy of Pediatrics , among others, strongly recommends increasing the minimum age to buy tobacco products to 21 nationwide. Doing so would result in nearly 250,000 fewer premature deaths and 50,000 fewer deaths from lung cancer among people born between 2000 and 2019, according to the Institute of Medicine report.

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