When he was 14, Mr Han Wenqi saw a man fall to his death.
He was on his way home from school when he witnessed a construction worker topple over the guard rails of a gondola in the air.
Shaken, he wondered: "How did this happen? Why didn't he anchor his harness? Where was the supervisor?"
The incident spurred him to pursue a career in workplace safety and health. He has spent 10 years in the construction industry, starting as a site supervisor and later becoming a safety officer.
Today, the 31-year-old is the principal trainer at centre Achieve Safety Training, conducting classes for several thousand workers a year.
Mr Han, who has worked on projects such as shopping centres, Build-To-Order flats and multi-storey carparks during his career, says safety professionals must tread a fine line between the cost concerns of their employers and the preservation of life and limb.
"Inadvertently, you will offend a lot of people," he says. "You could even risk losing your rice bowl."
Once, during the building of a major hotel, he upset colleagues when he delayed construction on a Sunday because a tower crane did not have a valid permit to be used at work. Some threatened to get him fired, although he was eventually able to make the upper management see sense.
Mr Han believes safety officers should be empowered to order work to stop at once when they see something dangerous on site.
"A two-hour internal stop-work order is better than a three-week one imposed by the Ministry of Manpower," he says.
He also feels that local supervisors have a responsibility to speak up as foreign workers are often hesitant to raise safety issues because they fear being sent back home.
"I'm Singaporean," he says. "If I lose my livelihood, at least I can go on JobStreet.com and look for something else. These guys, they can lose everything."
Mr Han has dealt first-hand with the consequences of such oversight. When workers died, he would sometimes have to pick up their next-of-kin from the airport and take them to the mortuary to identify the bodies.
"This is never an easy process," he says. "The first thing the family asks is, 'How did he die? Why couldn't you do something to protect him?'"
He asks workers to put up photos of their families around their workplaces. "Many take safety for granted. They think it won't happen to them. I want to remind them of the reason they work, which is to send money home to their families. Every worker is someone's husband, son or father."