Public health experts have an unusual suggestion for reducing teen smoking: Give just about any movie that depicts tobacco use an automatic R rating.

If that were to happen, as many as 5.6 million kids who are alive today would be spared a tobacco habit that will ultimately lead to their death, according to the authors of a report published this month by the Centers for Disease Control and Prevention.

The study’s primary aim was to assess Hollywood’s progress in keeping “tobacco incidents” out of the movies most likely to be seen by America’s kids and teens. Researchers who focus on this area define such incidents as “the use or implied use of a tobacco product (cigarettes, cigars, pipes, hookah, smokeless tobacco products, and electronic cigarettes) by an actor.” If two characters are smoking during a conversation, that counts as two tobacco incidents. If one of those characters is holding a pack of cigarettes in another scene, that qualifies as another incident.

A group called Breathe California in Sacramento keeps track of tobacco incidents in all movies that spend at least one week among the nation’s top 10 highest-grossing films. At least two raters assess each movie, and their findings are collected in a database that’s part of a project known as Thumbs Up! Thumbs Down!, or TUTD.

The study’s authors examined TUTD records from 2010 to 2016, focusing on movies with a G, PG or PG-13 rating. These were the movies kids were most likely to see, they reasoned.

The good news is that tobacco is making appearances in fewer movies. In 2010, 31percent of movies with youth-friendly ratings had at least one tobacco incident. By 2016, that figure had dropped to 26percent, according to the study.

Tobacco made a grand total of just four appearances in movies rated G or PG in 2016. That represents an 87percent decline from 2010, when there were 30 such appearances. And among PG-13 movies, the proportion that included at least one tobacco incident fell from 43percent in 2010 to 35percent in 2016.

But although tobacco appeared onscreen in fewer PG-13 movies over time, the total number of these appearances rose from 564 in 2010 to 809 in 2016, a 43percent increase.

This means tobacco incidents were concentrated into fewer movies. A kid watching a youth-rated movie that depicted tobacco in 2010 would have seen 22 incidents during the course of that film. By 2016, that figure had risen 55percent, to 34 incidents.

The study’s authors noted another problem: Efforts to keep tobacco out of movies aimed at kids appear to be faltering.

“Since 2010 there has been no progress in reducing the total number of tobacco incidents in youth-rated movies,” they wrote. “Had the trend established from 2005 to 2010 continued, all youth-rated films would have been smoke-free by 2015.”

With progress at a standstill, they added, “enhanced measures to address tobacco incidents in movies are warranted.”

These measures could start with a policy that would give a movie an R rating if it contained even one tobacco incident. That would greatly reduce the chances that younger, more impressionable moviegoers would see flattering depictions of smoking.

There would be a few exceptions. One would be for movies that include the downsides of tobacco use. Another would be for movies about historical figures who actually used tobacco.

The Motion Picture Association of America says it considers smoking — along with nudity, violence and adult language — when deciding what rating a movie deserves. But smoking rarely, if ever, earns a movie an R.

An earlier analysis of movies that came out between 1993 and 2003 concluded that if such a policy had been in effect during those years, the number of teens who took up smoking would be 18percent lower.

The U.S. Surgeon General added that this R-rating policy was likely to make a difference. Indeed, it would have an effect comparable to that of raising the price of a pack of cigarettes from $6 to $7.50.

Another idea is to make sure states aren’t giving subsidies to movies that includes tobacco incidents. If that sounds like small potatoes, consider this: Between 2010 and 2016, states gave about $3.5 billion in tax credits and other public subsidies to film productions that put tobacco on the big screen.

All of these policy prescriptions assume that the more times kids are exposed to tobacco use onscreen, the greater the chances that they’ll decide to experiment with tobacco themselves. The Surgeon General has warned that some of those teens will wind up with a long-term habit.

The study was published in the CDC’s Morbidity and Mortality Weekly Report.