Voices calling for stricter safety standards at workplaces are growing louder after a slew of industrial accidents took several lives over the weekend.

On Friday morning, a worker was killed when he suffocated while working inside a 3-meter-deep manhole in Namyeong-dong, central Seoul. Two others were immediately taken to a nearby hospital and one remains unconscious, police said.

According to police officials, the workers were measuring the exact locations of the local water supply systems on Thursday night but soon called for help. Local police cited oxygen deprivation as the likely cause of the tragedy.

“In summertime, the high temperature and humidity in a closed space become an environment for microbes to grow at a rapid pace by emitting toxic gas and removing oxygen,” said a researcher at the Korea Occupational Safety and Health Agency.

“Before entering underground, the workers are instructed to measure oxygen density in advance, ensure ventilation and then enter with protective devices,” he said.

The police are investigating whether the workers followed the guidelines.

The incident came on the heels of another tragic accident which took the lives of two construction workers.

A three-story commercial building in Cheonho-dong in eastern Seoul collapsed Wednesday during unauthorized renovation work.

A 44-year-old worker surnamed Kim died on the spot. Another, a 58-year-old surnamed Lee, was rescued from the rubble 15 hours after the collapse but died from excessive bleeding shortly after he was taken to hospital. Paramedics said they had to amputate part of his leg to remove him from the wreckage.

Investigators said the building was already 40 years old and was widely perceived to be “on the verge of a breakdown.”

“The workers were working at the ground floor, tearing down all the walls. The pressure from the second and third floors was massive and the pillars weren’t capable of sustaining the walls being dismantled,” said an officer at Gangdong Fire Station.

According to Gangdong District Office, the interior contractor did not report the renovation to the local authorities.

“The construction went for more than 10 days. That’s a huge process,” a resident told a local daily.

Police assume the workers failed to follow safety regulations to shorten the period of work.

In a similar incident earlier this month, four repairmen fixing an air conditioning system at Emart, the nation’s largest retailer, were found dead, apparently suffocated by refrigerant gas. Local police said the deceased workers seemed to have used no protection tools since the work was minor and routine to them.

“In summer, many people tend to skip safety measures at work because of the hot weather, which elevates the risk of industry accidents,” the occupational safety expert said.

The organization conducts an annual campaign for workplace safety including precautionary measures. “Workers should be reminded of the guidelines all the time because they are directly related to their own safety and life,” he added.

By Bae Ji-sook (baejisook@heraldcorp.com)