The National Institute for Occupational Safety and Health (NIOSH) has proposed that only workers possessing competent certificates from training providers registered with the Department of Occupational Safety and Heath (DOSH) are allowed to work in confined spaces.

NIOSH chairman Tan Sri Lee Lam Thye said such a regulation should be implemented and complied with so as to avoid recent incidents in which several workers were killed while carrying out work in confined spaces such as tanks, vessels and boilers from recurring.

"These tragic incidents have raised serious questions about the safety of workers, employers and contractors involved and should be investigated to ensure they adhere to the regulations under the Occupational Safety and Health Act (OSHA) 1994," he said in a statement here Friday.

Lee said in the latest incident in Tawai, Sabah three men died after inhaling fumes from welding works while repairing a leak on a barge at the jetty in Kampung Apas Parit.

Prior to that, he said, two men died while carrying out maintenance work on a hole in a drain in front of a shopping centre in Ipoh, Perak on April 17 while on Feb 13, an employee of a Vietnamese cargo ship and three others were admitted to the hospital after inhaling toxic fumes in the rice storeroom of the ship berthed at the Kota Kinabalu Port.

Meanwhile Lee advised employees working in confined spaces to be careful as their work environment is more hazardous than a normal work site due to the risks of poor air quality; chemical, biological, radiation and fire threats; loud noises and extreme temperatures; low visibility and hazardous chemical waste.

"In most cases, the cause of death is due to the inhaling of toxic gases or lack of oxygen,'' he added. -BERNAMA