Zheng Zhaorui, a veteran immigration inspection officer, may look ordinary at first sight, but his reputation for fighting drug trafficking has made him famous among his peers.

In his 16 years at the Mukang Border Inspection Station in Mangshi city, Yunnan province, Zheng has prevented more than 460 kilograms of drugs - mainly opium, heroin and methamphetamine - from being sold on China's streets.

His notes about drug detection techniques - including locating narcotics hidden in trucks and the human body - and identifying users are included as examples in Narcotics Control, a textbook used in police academies nationwide.

Yunnan, in China's far southwest, shares a more than 4,000-kilometer border with Myanmar to the west and Laos to the south, and as such, it is a gateway targeted by drug traffickers.

Located on National Highway 320, which links the border city of Ruili with Shanghai in the east, the station in Mukang is less than 100 km from the Golden Triangle, Asia's largest opium-producing area that straddles Myanmar, Laos and Thailand. It is the only major inspection station checking for contraband in the thousands of vehicles that pass through the border every day, heading for destinations nationwide.

Since the station was founded in 1981, its officers have checked more than 13 million vehicles and prevented 10.2 metric tons of drugs, 88 guns, 1,370 bullets and more than 27,100 protected animals from being brought into the country.

"Our daily work is challenging and life-threatening and we are required to wear bullet-and stab-proof vests to ward off attacks," Zheng said.

"Even wearing a full set of body armor, officers are still exposed to unpredictable dangers. Drug cases vary one from another and we often face life-and-death situations."

The officers usually question drivers and make preliminary examinations of vehicles when they are stopped at the checkpoint for inspection.

A decision must be made immediately whether to give drivers the green light or ask them to pull over for a thorough examination. That requires a high degree of experience and tact.

"We are aware of several hundreds of ways of hiding and smuggling drugs, but some can be very devious and surprising," Zheng said.

"The officers have to be vigilant with all the vehicles passing through our checkpoint because you can never predict the next new smuggling technique."

Traffickers are adept at using everyday objects to transport drugs. Soda cans, vehicle water tanks, tires, livestock, shoes, computers and handicraft items have all been used as hiding places, while children, pregnant women and disabled people are frequently employed to carry consignments, he said.

Some drug traffickers have tried to bribe officers, while others have attempted to seduce them, yet there has never been any corruption or collusion at the checkpoint because the officers are determined to prevent narcotics from passing through, Zheng said.

"One drug addict can ruin a whole family, and even taking a drug once can make people addicted. Our job is to ensure that fewer families fall victim to drugs," he said.