More teenagers in Korea swear more often than two years ago, a straw poll by the Korean Federation of Teachers' Associations for the Chosun Ilbo finds.
The KFTA polled 285 teachers across the nation last week.
In 2011, 53.9 percent of teachers in a similar poll said that over 50 percent of their charges use swearwords, but that rose to 57.2 percent this time.
The proportion of teachers who said more than 75 percent of their students curse rose from 24.6 percent in 2011 to 27.2 percent.
Asked why they think youngsters swear, 39.3 percent cited habit and 22.2 percent said because they are afraid to be isolated from their peers.
Some 56.6 percent said they hear students use swearwords, vulgar language and slang nearly every day, compared to 55.5 percent in the 2011 poll.
Children also seem to start swearing younger. Asked in which year children swear the most, 78.8 percent of the teachers surveyed said elementary school and first and second years of middle school, up from 71.8 percent two years ago. Among them, the proportion who picked the middle school years rose from 43.3 percent to 53.4 percent.
Abusive language is not just reserved for their peers. Some eight out of 10 teachers said they heard children referring to them using mockery and swearwords, but only half of them or 43.9 percent said they tried to discipline them.
Some experts worry that the use of bad language points to a malaise of the public education system and the family. Fewer parents talk to their children, and schools neglect character-building in favor of cramming for exams. Meanwhile the Internet and mass media set a bad example.
Kim Hyung-bae, a researcher at the National Institute of the Korean Language, said, "The results show that youngsters who grow up in big cities and are from low-income households tend to use bad language more often."