More than 3 out of every 10 middle and high school students are being exposed to secondhand smoke, a state-run health promotion agency said in a report Sunday.

The Korea Health Promotion Foundation said 31.8 percent of male students and 35.6 percent of female students were found to have experienced passive smoking in their daily lives. On average, teenage boys were exposed to secondhand smoke 3.41 days a week while girls experienced it 3.6 days a week. The study was based on health data of 74,186 students from 797 schools around the country compiled by the Korea Centers for Disease Control and Prevention in 2012.

Younger teenagers were more vulnerable to passive smoking than those in the highest grades in high school.

More than 36 percent of middle school freshmen were exposed to secondhand smoke but the rate dropped to 31 percent for high school seniors.

Family income and the father’s educational background were found to be linked to the rate of teens’ exposure to secondhand smoke.

Students who said they belonged to a low-income family were 1.37 times more likely to experience passive smoking than those who regarded themselves as members of high-income families. In addition, students whose father did not graduate from college were 1.21 times more likely to be exposed to secondhand smoke.

Researchers at the KHPF claimed that raising taxes on tobacco would decrease the smoking rate among low-income families.

“Teens from low-income families have higher chances of being exposed to secondhand smoke. So the government should consider raising the tobacco taxes further,” the foundation said in the report.

By Yoon Min-sik (minsikyoon@heraldcorp.com)