California could be among the only states to raise the smoking age. (REUTERS/Kim Kyung-Hoon)

California lawmakers are considering raising the smoking age from 18 to 21. Their argument is that doing so will significantly decrease the number of smokers in the state and save billions in healthcare costs. But how effective would it actually be?

One indicator is the groups that have that come out for and against it. Health groups are for it, like the American Academy of Pediatrics, the American Cancer Society Cancer Action Network and the California Medical Association, while those opposed are the Cigar Association of America and the California Retailers Association, according to the Los Angeles Times. This bill would impact their bottom lines, cutting off customers, and it's no joke.

And there's data that backs up the idea's effectiveness. Although most states set the minimum age at 18, Alabama, Alaska, New Jersey and Utah set it at 19, and some localities have set it at 21. Higher age limits seem to correspond with lower smoke rates in these states; Utah and New Jersey also have among the lowest smoking rates in the country, No. 1 and No. 5, per Gallup, while Alaska has the most improved, and Alabama is somewhat of an outlier in the South, as it's not among the states with the highest smoking rates, like its neighbors Mississippi and Louisiana.

And according to a study by the Institute of Medicine of the National Academies, increasing the minimum legal age to smoke, shown below as "MLA," has different rates of effectiveness depending on how old people are. Those most likely to smoke less where there are higher MLAs are 15-to-17-year olds.

The study says 90 percent of adults who are daily smokers first used a cigarette before they were 19. That suggests the key to decreasing cigarette use is decreasing use by teenagers, most of whom are too young to use them legally. The way these kids get cigarettes before they're old enough is generally through their social circles -- and often their older, legal friends. The higher you raise the minimum age, the less likely you are to have teenagers with friends that old; 16-year olds and 19-year olds were in high school together at the same time, 16-year olds and 21-year olds were not.

The study suggests changing the MLA to 21 can reduce "initiation rates" -- i.e. those who start smoking -- among those 15-to-17-years-old by 25 percent, or one-quarter. (Other groups saw smaller reductions.)

About 10 percent of California high schoolers smoke, according to the Campaign for Tobacco Free Kids, so such a drop could put a dent in that. And the group says smoking-caused government expenditures, like healthcare costs covered by state Medicaid, cost households $745 a year.

This, we would emphasize, doesn't take into account the idea of taking away rights from young adults -- i.e. whether an 18-year old or even a 20-year old who can serve in the military, etc., should be prevented from being able to smoke. This is the same issue often raised when it comes to the drinking age, which is 21 across the country.

But the data do suggest it could reduce smoking.

California's bill was passed by its state Senate and will head to its state Assembly, and Hawaii's legislature has passed a similar bill, which is waiting for the governor's signature.

If they pass and put a dent in smoking rates, we might soon see other states bump up their minimum ages too.