Before each mission, Yan Qun takes a picture of himself, and then deletes it when the bomb is defused. To date, he has taken 278 of these "just in case" pictures.

Yan, 41, is deputy head of the bomb-disposal squad of the fifth detachment of the Beijing Public Security Bureau's counterterrorism department. He has disassembled 27 explosive devices by hand in his 23-year career.

"It's like an exciting scene from a thrilling movie, but without a script. The work is fraught with uncertainty and you can never rehearse," he said.

Yan was once three minutes from death. In 2004, a suspect threatened to blow up a public baths in Beijing after a dispute with its owner. Days later, a bomb was found in a changing room locker. Detonation had been set for 5 pm, but the timer had stopped at 4:53 pm.

"Homemade devices are usually unstable, and cutting the outside wiring can trigger an immediate explosion. The only way was to defuse it," Yan said.

But when he removed the bomb from the locker for more working space, the timer restarted.

"Normally the safest course would be to evacuate all team members and let it explode," he said.

In this case, however, the damage would have been great, and the evidence would also have been destroyed. So Yan volunteered to stay with just seven minutes to spare.

"You work to only the sound of your own breathing in the helmet. Alone in the area, you have no one to talk to at the critical moment," he said.

At 4:57 pm, Yan made it, although inside his 35-kilogram protective suit his hair was as wet as if he had just washed it. "A small explosion might leave you with your body intact, although without hands," he said, with black humor.

Yan is now a key figure among his squad's 35 members. Three to five years of training is required before a recruit can deal with a real device.

To practice under pressure, candidates run in their heavy work suits before using chopsticks to pick out ball-bearings from a bowl of green beans. It takes the fine skills of an embroiderer, combined with a mind that can race against death.

"This profession has a high dropout rate. Some perform well in the training but cannot cope in a real situation," Yan said.

"My biggest wish is that by the time I'm old and looking through the family photo album of our squad, no one will have been killed or injured."