You see it so often in the movies - characters smoking. It has long been a staple of Hollywood classics, and is still a common occurrence on movie screens. The Motion Picture Association of America, the group that sets movie ratings, has decided to crack down to try and stop it.
Here's ABC's Dan Harris.
It was Superman Two in 1980 that first lit up the public health community. Philip Morris paid to have Marlboro cigarettes featured prominently.
Stars had been smoking in the movies for decades like in classics like Casablanca. After Superman Two, anti-smoking activists started an aggressive campaign.
"Smoking is not presented as a dirty habit. Smoking is not presented as an addiction," said Professor Stanton Glantz with the University of California in San Francisco. "It's generally presented as something glamorous, sexy people are doing."
Change came slowly. To this day in the movies, you can see smoking among men, women, people on other planets and even cartoons characters.
"Children model movie stars all the time. When they see them smoking, they follow them in that way too," said Matt Myers with the Campaign for Tobacco Free Kids.
Now the MPAA, which rates movies, says it will take smoking into account, along with violence and nudity.
"Clearly smoking is increasingly an unacceptable behavior in our society," said the MPAA in a statement.
The MPAA also said it will make exceptions for historical movies like Good Night and Good Luck, which portrays real-life journalist Edward R. Murrow - a big smoker. While anti-smoking activists agree with those exceptions, they want the vast majority of movies that feature smoking to automatically get an R rating.
"We think that the simple act of integrating into the rating system so that smoking the movies got an R would prevent 200,000 kids a year from starting to smoke," Glantz said.
Most anti-smoking activists don't want old movies to get new ratings, but if a studio wanted to make Casablanca today, to keep the G rating Bogart would have to lose his butts.
Dan Harris, ABC News, New York
In a Dartmouth University study researchers looked at 534 recent box-office hits, many rated PG-13, and 74 percent of them contained smoking. The study also concluded that 52 percent, more than half, of teenagers who start smoking said they do it because they see it in movies.