THURSDAY, Aug. 4 (HealthDay News) -- Compared with high school smokers two decades ago, today's teen smokers are more likely to smoke only occasionally, or smoke fewer cigarettes each day, according to a new study.

Researchers revealed that among high school smokers, the percentage of teens considered heavy smokers -- having more than 11 cigarettes each day -- dropped from 18 percent in 1991 to about 8 percent in 2009. At the same time, occasional smoking rose from 67 percent to 79 percent.

"I have noticed more teenagers seem be smoking just a few cigarettes per day," Dr. John Frohna, a professor of pediatrics and internal medicine at University of Wisconsin-Madison, said in a news release from the Center for Advancing Health.

In the study, which is published online and in the September issue of the American Journal of Preventive Medicine, researchers analyzed data from students in grades 9 through 12 who participated in national Youth Risk Behavior Surveys, which included about 11,000 to 16,410 public and private high school students. The surveys included questions about smoking habits.

The study found that of the 19.5 percent of today's high school students who call themselves "smokers," most don't smoke every day or very often.

The downward trend of heavy smoking among high school students, however, did not apply to black or Hispanic teens. Researchers found no change in the smoking habits of black students surveyed. Meanwhile, the percentage of Hispanic students who smoked heavily increased from 3.1 percent to 6.4 percent.

Although fewer teens are smoking heavily, even occasional smoking is cause for alarm, noted Frohna. "I do think there are fewer kids in my practice who are smoking heavily, but I remain concerned that they are smoking at all. We need to continue to reinforce the message that any smoking is unsafe. We also need to ensure strong enforcement of laws against selling cigarettes to children," he said.

"It is important to note that light and intermittent smoking still has significant health risks," the study's co-author, Terry Pechacek, associate director for science at the Office on Smoking and Health of the U.S. Centers for Disease Control and Prevention, noted in the news release. "Even though smoking prevalence among youth and adults has slowed, we're closely watching to see whether light and intermittent smoking persists into adulthood despite tobacco control policies and changes in social norms that have previously led to sharper declines."

More information

The Nemours Foundation has more about teens and smoking.