The retired middle-school teacher went missing on western Beijing's Tietuo Mountain on Sept 30. After his disappearance, many people volunteered to search for him, and the number of rescuers once stood at 300. Now, just the Lvye ("green field" in Chinese) Rescue Team (LRT), an NGO based in Beijing, is sticking to its task.

"Looking for a missing person in the mountain is like searching for a needle in a vast sea. But the reason we keep trying to find his body is to give his relatives some comfort," says LRT member Xu.

"We know he must be somewhere in the mountain. We just want to keep him company so he won't be alone."

Since China's opening-up, the number of outdoor enthusiasts has increased dramatically. Many outdoor groups have emerged across the country. The number of outdoor sports clubs has rocketed to nearly 1,000, according to chinanews.com.

On the other hand, related accidents have increased. Consequently, some experienced outdoor enthusiasts have turned to rescue work. LRT is a good example.

Founded in 2007, LRT is North China's largest outdoor rescue team, with a membership of more than 130, of whom one in four is female.

The rescue crews are mainly experienced outdoor sports enthusiasts. Most of them are aged 18-60 and are based in Beijing. LRT also has branches in Qinghai, Sichuan, Guizhou and Jiangsu provinces.

Over the past 18 months it has rescued 50 people from mountains around the capital city.

"Many outdoor sports enthusiasts don't dare sign up for our team as they are afraid of not being strong enough to do the job," LRT member Zhang Hao recalls.

"But physical strength is not the most important thing about being a good rescuer. It is about the rich experience of outdoor activities."

A few rescuers have been living on Tietuo Mountain during their search for Ren, while other LRT members do the job at weekends, working from 9 am to 4 pm.

Xu says the reason they haven't found him is that the 1,000-m mountain is difficult to climb. Covered by bushes, it has been exploited for coal since the Ming Dynasty (1368-1644). It is these small coal pits that have posed great difficulties for rescuers trying to find the 61-year-old.

"We have been wherever we can go - cliffs and ravines for instance. Previously there were no tracks in the mountain. Now, some paths have emerged because of our searching," Xu adds.

Yang Yanwu is a typical "donkey" (the nickname of outdoor sports enthusiasts in Chinese), who has been involved in outdoor sports for more than 7 years. Despite being a businessman, the 32-year-old prefers to dress in outdoor clothes, and takes his GPS with him at all times, even when dining out.

"Rescuing people can generate a sense of accomplishment. Honestly, I am addicted to the feeling," the senior LRT member says with a smile.

He recalls, two years ago, about 39 people climbed Baihua Mountain on the outskirts of Beijing. When they reached the top of the mountain in the evening, it started snowing and the path was covered so they had no idea how to get down.

They made an emergency call to the police. Yang was asked by the police to help out.

After hours of waiting on the top of the mountain many of the climbers had collapsed from exhaustion. When Yang eventually reached the top, they were so excited they were speechless. "It was my most successful rescue experience. The feeling was so great it was worth more than money," he says.

Beijing is surrounded by mountains - Haituo Mountain in the north, Lingshan Mountain in the west and Yunmeng Mountain in the east - with altitudes ranging from 1,900 m to 2,000 m.

Yang points out that many people lack awareness of the risks they might encounter in the mountains, as they think naively that outdoor activities are like wandering around public parks.

"Up to 90 percent of people don't bring a map and compass when climbing mountains, and they don't even prepare first-aid medicine - bandages and antidotes for snakebite for instance," he says.

When they lose their way, some decide which way to go by throwing their shoes down and seeing which way they point, Yang adds.

In order to reduce the likelihood of getting lost, LRT has made road signs in the mountains, giving basic information, such as the rescue hotline, the mountain's altitude, longitude and latitude.

"Although many of the road signs are hand-made, they definitely lift the hopes of (lost) climbers," LRT member Zhang Hao says.

Normally, rescuers work in groups of at least three or four, but sometimes only one person is able to handle the conditions and guide lost people out of the mountain.

This September, for example, a family of three lost its way in Yunmeng Mountain. After receiving their call, the police immediately set off to look for them. But they also got lost.

LRT member Du Chong played a crucial role in locating them.

Since he knew the mountain like the back of his hand, Du asked the family to describe the surroundings by telephone, then told them where to go. As darkness and low temperature set in, Du told them the way to an abandoned house to stay overnight in the mountain. All of them were rescued the next day.

"This was the most efficient rescue operation I have known. So, we love to address Du as a walking map," Zhang comments with pride.

The outdoor rescue system has some imperfections in China. So far, local firemen take primary responsibility for rescuing people from the mountain, which is not their forte, LRT leader Zhang Yong says.

As such, LRT has co-operated with the local fire brigade since April, to ensure sure that the rescue team is informed as soon as an emergency happens. Zhang admits a lack of funds has left the rescue team ill equipped, especially in terms of transportation and communication equipment. "We don't even have a car for rescue operations. Asking a favor from friends is not a real solution."

Yang adds what they need most is to learn more from Western countries.

"Outdoor rescue in some foreign countries - Italy and the United States for instance -can be traced back to after World War II. As a starter, we long for their rich experience and professional training," Yang says.

LRT will be renamed Lantian Rescue Team next year when it cooperates with the Red Cross Society of Beijing, according to Zhang Yong.