The number of children who smoke is worrying doctors, with more than a quarter of students who use cigarettes saying they started puffing at age 10.

A survey released by the Beijing Center for Disease Control and Prevention (CDC) last week that was carried out early this year among more than 10,000 middle school students found 25 percent had tried smoking.

Nearly 10 percent said they had smoked in the previous 30 days, and more than 5 percent had smoked at least one cigarette a week during the previous three months.

"I always see students from Wanshousi Middle School smoking outside the school gate. Most of them seem to be from the higher grades," said Zhang Huayan, who graduated from a primary school next to the middle school.

Research released by the CDC in 2009 shows that about 20 percent of students smoked for the first time when they were younger than 7. School officials said they are trying to counter the interest in smoking among such young children.

"We have been paying more attention to tobacco awareness lessons in recent years and education about the dangers at a younger age is an effective method," said Guo Xin, vice-director of the school health department with the capital's CDC.

The center made learning materials available to 15 primary schools in Changping, Daxing and Dongcheng districts on Dec 4. About 8,000 students will use the materials to learn about tobacco.

The latest CDC survey also reveals that more than half of students reported regularly seeing tobacco-related images on TV and nearly 40 percent believed smoking made actors look more attractive and mature. About 33 percent said they would try smoking because actors made it look attractive.

Duan Jiali, an official from the Beijing CDC said TV dramas tend to connect smoking with fashion and being sexy and those dramas make a strong impression on young people.

"This presents a growing challenge for our anti-tobacco campaign," she said.

Sun Jiangping, a doctor from the Medical Department at Peking University, said smoking gives teenagers the sense they are "being adult".

"Many children do not believe the harm smoking can do to them. We need to make it more vivid and need it to make more of an impression."

Liu Qi, a teacher from Yucai School in Xuanwu district, said other improvements are needed in addition to better education. Liu said students can easily buy cigarettes from shops and that should also be tackled.

And to protect children's health, education will likely need to extend to people who smoke around them as well.

According to statistics from the Campaign for Tobacco-free Kids, between 40 percent and 80 percent of children endure second-hand smoke in their homes.

Qin Zhongwei contributed to this story.