A fatal industrial accident occurred in the West Kowloon Cultural District, and two male workers died this morning (24th) suspected of inhalation of high concentrations of hydrogen sulfide poisoning. Some medical experts said that hydrogen sulfide is heavier than air, easy to deposit in low places and confined spaces, if its concentration exceeds 100ppm (parts per million) will have immediate health and life danger, but generally inhale a small amount of hydrogen sulfide in open space, it will not cause death. Asked about the fact that two workers started work during the day yesterday, only today the workers found that they had not left the underground pipe. Some safety consultants in the construction industry bluntly said, "It's actually so strange!" , because the industry believes that the work in underground pipelines generally does not exceed 2 hours.

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Orange pipes visible at the scene of the accident for ventilation and exhaust. Li Guangsheng, an occupational safety adviser to the Federation of Construction Trade Unions, said that the orange pipe, also known as canvas throat, which is ventilated in closed places, can flexibly retract. However, sometimes even if there is a ventilation throat, it may not be safe, depending on the depth of the ventilation throat and whether the ventilation can effectively dilute the dangerous gas, if the ventilation is not enough, the dilution effect cannot be achieved, there may be accidents.

He also pointed out that workers working in underground pipelines are required by law to complete the "Approved Worker Course" approved by the Labour Department and to have a qualified person assess the on-site environment, with a minimum of 5 aspects, including the risk of explosion, heat stroke, hazardous gases, drowning in water immersion and flowing solids, and workers are required to wear personal protective equipment as recommended in the assessment report. According to the law, when working in underground pipes, you must wear a full oxygen tank, along with a respirator, a seat belt and a rope, and the other end of the rope must be held by another worker outside. Because in the event of danger, workers outside can pull out the workers inside the pipeline in time, he stressed that there must be someone outside the closed site to monitor the work situation, and to maintain communication with the workers working in the pipeline. No one knows what happened, and Mimi is out of help."

Orange pipes visible at the scene of the accident for ventilation and exhaust. (Photo by Zheng Jiahui)

Lee also pointed out that workers working in underground pipelines are also required to wear sirens, which will sound an alarm within 20 seconds if the worker does not move after 30 seconds. In addition, when asked about the fact that 2 workers worked during the day yesterday and were only found to have not left the underground pipeline this morning, Li bluntly said, "It's actually strange!" , because a work permit needs to be signed before entering a confined site, and the industry believes that it is generally no more than 2 hours to work in underground pipelines.

Li Guangsheng, an occupational safety consultant of the Construction Industry Federation, said that if the ventilation is not enough to achieve the dilution effect, there is a chance of accidents. (Provided by interviewee)

Hydrogen sulfide is easy to deposit, and confined spaces can be fatal

Jin Dongyan, a professor in the Department of Biochemistry at the Li Ka Shing School of Medicine of the University of Hong Kong, said that hydrogen sulfide is one of the gases of biogas, and biogas is a mixed gas, mainly alkanes such as methane. Hydrogen sulfide smells like rotten eggs, but it is colorless, not visible to the naked eye, and it is highly flammable. In addition, because hydrogen sulfide is heavier than air, it is easy to be deposited in low places and confined spaces, if its concentration exceeds 100ppm (parts per million) will have immediate health and life danger, exposure to 50 to 100ppm within an hour can cause rhinitis, conjunctivitis and acute dyspnea, exposure to 700 to 1000ppm will quickly fall into coma, respiratory arrest, and even death. The limit of the permissible exposure dose in an average of 8 hours is 1 ppm, while the limit of the permissible contact dose within 10 minutes is 5 ppm.

Jin Dongyan, a professor in the Department of Biochemistry at the Li Ka Shing Faculty of Medicine at the University of Hong Kong, said that hydrogen sulfide concentrations exceeding 100ppm (parts per million) pose immediate health and life risks. (Online image)

However, Jin Dongyan said that the limit of the allowable exposure dose during this time is slightly different from the international standards, and some organizations believe that if there is only a single exposure to gas within 8 hours, and it does not exceed 10 minutes, the limit of the allowable contact dose can reach 50ppm, but it is very close to 100ppm that affects immediate health and life danger. Jin also pointed out that if people inhale high concentrations of hydrogen sulfide in confined spaces, they can cause death for a short time, but generally inhale a small amount of hydrogen sulfide in open spaces, it will not cause death.

Two workers in the West Kowloon Cultural Zone were suspected of hydrogen sulfide poisoning and died The rescue situation in the pipeline was exposed, and the site of the West Kowloon Cultural District was suspected of biogas leakage 2. The workers were in a coma and sent to the hospital for rescue and did not treat