The World Health Organization (WHO) says movies that contain smoking scenes or tobacco imagery should receive an adult rating, in an effort to prevent young people from starting to smoke.

In a report, “Smoke-Free Movies: From Evidence to Action,” WHO said 44 percent of all Hollywood movies in 2014 featured smoking, and 36 percent of films with tobacco use were rated for young people.

“Because smoking on screen is uniquely vivid and because young people see so many films so often, its effect in promoting smoking initiation is striking,” the report said. “The most vulnerable age group, adolescents, should not continue to be exposed to the most powerful promotional channel for smoking imagery available in today’s globalized economy.”

WHO defines movies with an “adult rating” as being suitable only for those ages 18 and older, CNBC reports. The group said possible exceptions could be made for older films, which would not need to be re-rated. Those films could have warning labels on DVDs and videos.

Exceptions also might be made for movies depicting actual historical figures who smoked, and for films that clearly show the dangerous effects of tobacco use. The report did not address e-cigarettes, the article notes.

Films should no longer display tobacco brands, WHO recommended. The report also called for airing anti-smoking ads before showing any film that included tobacco imagery, and withdrawing state or lottery funding from film productions that promote smoking.

“The measures have enormous potential for averting the growing burden of disease due to tobacco use, particularly in low- and middle-income countries,” the report noted.

“With even tighter restrictions on tobacco advertising, film remains one of the last channels exposing millions of adolescents to smoking imagery without restrictions,” Dr. Douglas Bettcher, WHO’s Director for the Department of Prevention of Noncommunicable Diseases, said in a news release.