Young American women commonly smoke, but only very lightly, or they smoke on some days but not others, a new study finds.

Researchers analyzed information from more than 9,700 women ages 18 to 25, who answered questions about their smoking habits in 2011.

Overall, about 30 percent of the women were current smokers, whereas 28 percent were former smokers and 41 percent had never smoked. Most of the current smokers were "very light smokers," who smoked five or fewer cigarettes per day.

Nearly 20 percent of all women in the study, and more than 60 percent of the current smokers, were very light smokers, according to the findings.

In addition, more than 70 percent of the very light smokers said they didn't smoke every day. The very light smokers were more likely than heavier smokers to have some college education, and were more likely to perceive smoking as carrying higher health risks.

"Health educators and health care providers working with women in emerging adulthood need to recognize the high prevalence of very light smoking in this population, and screen for any level of tobacco use," the researchers, wrote in the July issue of the journal Preventing Chronic Disease. [Kick the Habit: 10 Scientific Quit-Smoking Tips]

In addition, some of the public health efforts aimed at getting people to quit smoking should be tailored to target very light smokers, the researchers said. People in this group may be less likely to identify themselves as smokers, but also more likely to recognize the high risks in smoking, the researchers said.

"Making very light smokers aware that even small amounts of tobacco are harmful would be important," study researcher Carole Holahan, of the Department of Kinesiology and Health Education at the University of Texas at Austin, told Live Science.

Even light smoking can carry health risks; very light smoking is linked with heart and lung problems, and an increased risk of cancer.

The study also found that very light smokers were more likely than nonsmokers to report depression and psychological distress. People in this group were also less likely to be married than any other group of smokers or nonsmokers.

Some people may become light smokers because they can't afford to buy a lot of cigarettes, the researchers said. Women in college, for example, may smoke at a light level because they attend parties on the weekend that promote smoking, study authors said. People may also start smoking lightly because of emotional stress, the researchers said.

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