Oregon has become the fifth state in the country to raise its smoking age to 21.

Gov. Kate Brown signed the bill on Wednesday. It will take effect at the start of 2018, barring anyone below the age of 21 from purchasing tobacco products.

Brown previously praised Lane County for raising its legal age, arguing that it was an important move to reducing smoking rates. “I want to make sure that we continue to reduce the number of young people starting to smoke, but it’s also critical that we reduce the number of people smoking,” she said in May.

Hawaii, California, New Jersey, and Maine have also raised their smoking ages, with Hawaii the first to vote to make the change back in 2015. This is, in short, becoming a popular strategy for addressing one of the gravest public health problems in human history.

While smoking rates have dropped in the past several years as policymakers have enacted tougher restrictions on tobacco, the death rate from smoking is still very high: By the latest estimates, smoking still kills 480,000 to 540,000 people in the US every year — far more than all other drug-related deaths, murders, and car crashes combined.

Many people, citing their own experiences smoking and drinking before they were of legal age, are likely skeptical of the arguments for Oregon’s law. But the research on this point is pretty clear: A higher minimum legal age for buying cigarettes really does save lives. Not only that, but the research shows that the logical comparison point — the minimum legal age for buying alcohol — saves lives too.

A higher nationwide smoking age would save lives

A 2015 report from the Institute of Medicine (IOM) found that raising the smoking age to 21 could prevent approximately 223,000 premature deaths among Americans born between 2000 and 2019.

The analysis, which reviewed the available research and used a mathematical model for its projections, concluded that increasing the minimum legal age to 21 would decrease smoking initiation rates by 25 percent among 15- to 17-year-olds, while other age groups up to 21 years old would see smaller but significant decreases. In total, IOM’s model projected that the increased minimum legal age would drive a 12 percent decrease in the prevalence of tobacco use by the time today’s teenagers became adults.

Richard Bonnie, a University of Virginia professor of health and law who headed the analysis, previously told me that delaying when people start smoking is crucial because older people — perhaps more aware of their mortality and the health effects of tobacco — are less likely to initiate smoking. About 90 percent of adults who become daily smokers report first using cigarettes before 19 years of age, and almost 100 percent report first use before 26, according to the IOM report. So preventing people from starting to smoke at a young age could very well stop them from smoking for a lifetime.

The higher legal age for smoking would delay the initiation rate in two ways. Most obviously, it would prevent 18- to 21-year-olds from legally purchasing cigarettes. But it would also have trickle-down effects on younger groups — particularly 15- to 17-year-olds — by limiting their access to friends and family who can buy cigarettes legally. The logic is simple: It’s possible that middle and high school students may have access to 18-year-old peers to purchase cigarettes now, but they’re likely not going to have as much access to people who are 21 or older, who will likely be in college or living their adult lives.

Older friends and family members “are largely where young people get their tobacco,” Bonnie said. “If you raise [the smoking age] to 21, over time we think that's going to have a significant effect on separating these social networks.”

The drinking age saves lives too

Raising the smoking age lends itself to comparisons to the minimum legal age for alcohol. Indeed, several people on social media and Reddit immediately drew the comparison when Hawaii voted to hike its smoking age in 2015.

Bonnie cautions against putting too much emphasis on this comparison. For one, there's a much bigger stigma against smoking than against drinking, which surely plays some role in people's obedience of the age laws. Furthermore, the age policies for drinking and smoking have different goals: Raising the smoking age is supposed to deter people from smoking altogether by delaying their initiation, while raising the drinking age is supposed to stop people from drinking only until they're more responsible adults.

Still, Bonnie notes that the research does show the drinking age works to delay some drinking. “The evidence is overwhelming [that] raising the age reduces consumption,” he said. “Even though consumption remains significant among the younger population and increases as people get older, it's still lower than it would be if you lowered the age to 18.”

A 2014 review of the research published in the Journal of Studies on Alcohol and Drugs bore this out: Although many young people disobey the drinking age, the evidence overwhelmingly suggests that it has depressed drinking and saved lives.

The review found that the elevated drinking age saves at least hundreds of lives annually as a result of reduced alcohol-related traffic fatalities among underage drivers. One study cited in the analysis found that the number of fatally injured drivers with a positive blood alcohol concentration decreased by 57 percent among those ages 16 to 20, compared with a 39 percent decrease for those 21 to 24 and 9 percent for those 25 and older, between 1982 and 1995, after the National Minimum Drinking Age Act of 1984 raised the legal drinking age from 18 to 21. Other studies had similar positive findings.

Critics of the drinking age commonly argue that it forces youth to drink in secret, which may lead to binge drinking as people stash booze to secretly consume all at once. But the review of the research found no evidence for this, and instead concluded that the national drinking age law reduced access to alcohol and consumption. And New Zealand, which reduced its drinking age from 20 to 18 in 1999, saw increases in drinking among ages 18 to 19 and even bigger increases among those 16 to 17 years old, as well as a rise in alcohol-related crashes among 15- to 19-year-olds.

William DeJong, a professor at Boston University School of Health and a co-author of the research review, suggested his findings for the drinking age may apply to the smoking age too. “The basic idea behind these laws is to reduce youth access to these substances,” he previously wrote in an email. “The evidence is clear that, the later a young person takes a first drink, the less likely they are to experience negative alcohol-related consequences as adults. And the later a young person starts to smoke, the less likely they are to develop a lifelong habit.”

The law accomplishes this in a similar way to a higher smoking age: Obviously, it makes it harder, if not nearly impossible, to purchase alcohol before someone is 21. But it also breaks up social groups in a way that makes alcohol less accessible: If the drinking age were 18, someone who is a freshman or sophomore in high school would be much more likely to have access to an 18-year-old senior. But if the drinking age is 21, a freshman or sophomore in high school is not going to have as easy access to a 21-year-old who's working or in college.

So the laws may not be perfect, and they may be disobeyed at times. But the overall evidence is suggestive: Higher minimum legal ages for smoking and drinking reduce use and save lives, and they do so by working exactly as one would expect.