Accident case analysis: one question per Monday (9). +3 wealth for participation, plus an additional 1–10 wealth for correct answers

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　At 8:00 on May 10, 2010, employees A and B from Company B were assigned by their company to the wastewater treatment workshop at Plant C to clear blocked wastewater pipes. The two arrived at the site and began working without going to Refinery C to complete any necessary procedures. Person A descended into a sewage well over 3 meters deep to clean the sludge using buckets, while Person B pulled it up from the wellhead with ropes. During the cleaning process, Jia discovered a layer of cement beneath the sludge with gas escaping from it; he then climbed out of the sewage well and used a long steel pipe to break up the cement block at the well’s opening. At around 11 o’clock, when Jia descended to the bottom of the well again along the ladder, he suddenly collapsed. B called for help as soon as he noticed it. C and other employees from Company B, who were working in the vicinity, rushed to the scene immediately. Bing went down the well to rescue people without taking any protective measures, and collapsed suddenly as soon as he reached the bottom of the well. B called for help loudly again. Special rescue personnel from Refinery C rushed to the scene upon hearing the news and descended into the well to rescue A and C. A and C died despite attempts to save them. The accident investigators tested the gases inside the sewage well, finding an oxygen concentration of 19.6%, a methane level of 2.7%, and a hydrogen sulfide level of 850 mg/m3. Based on the above scenario. Answer the questions (multiple-choice). 1 The possible accidents that can occur when working in the sewage wells of C Refinery include (　). View materials A. Fire B. Other explosions C. Drowning D. Asphyxiation due to poisoning E. Mechanical injuries 2. The causes of Party C’s death in this accident include ( ). View materials: A. Blind rescue attempts; B. Asphyxiation; C. Poisoning; D. Lack of protection; E. Falls from height. When entering the sewage wells of C Oil Refinery to carry out cleaning work, the personal protective equipment that should be worn includes ( ). View materials A. Safety helmet B. Air respirator C. Conductive shoes D. Earplugs E. Protective gloves 4 The indirect causes of this accident include ( ). View materials: A. Insufficient training for the workers. B. Defects in the cleaning tools used by the workers. C. Improper rescue procedures. D. Workers failing to wear protective equipment. E. Workers carrying out operations in violation of regulations. 5 Before entering the sewage wells at C Refinery, gas testing is required; the gases that should typically be tested include ( ). View materials A. Flammable gases B. Toxic gases C. Oxygen D. Hydrogen E. Carbon dioxide Answers and explanations: 1. The accidents that may occur during operations in the sewage wells of Refinery C include (C, D). View materials A. Fire B. Other explosions C. Drowning D. Poisoning and asphyxiation E. Mechanical injuries Reference explanation: Hydrogen sulfide is a toxic gas that can cause poisoning and asphyxiation. The sewage well contains a large amount of wastewater, and operators running into trouble there can easily suffer drowning. 　2 The causes of Party C’s death in this accident include (A, B, C, D). View materials: A. Blind rescue attempts; B. Asphyxiation; C. Poisoning; D. Lack of protection; E. Fall from a height. Reference explanation: Employee C did not know the basic principles of rescuing someone who has been poisoned, and his blind attempts at rescue were the main cause of his death due to poisoning. The lack of protective equipment also contributed to his death. This accident resulted from death due to poisoning and asphyxiation; therefore, poisoning and asphyxiation are also considered causes of death. 　　When entering the sewage wells of C Refinery for cleaning operations, the personal protective equipment that should be worn includes (A, B, E). View materials A. Safety helmet B. Air respirator C. Conductive shoes D. Earplugs E. Protective gloves Reference explanation: In this scenario, the hazards that may arise from sewage wells include object strikes, poisoning, and suffocation. To prevent object strikes, safety helmets and protective gloves should be worn; to prevent poisoning and suffocation, air respirators should be worn. 　　4 The indirect causes of this accident include (A, C). Review the materials: A. Insufficient training for the workers. B. Defects in the cleaning tools used by the workers. C. Improper rescue procedures. D. Workers failing to wear protective equipment. E. Workers carrying out operations in violation of regulations. Reference explanation: According to the \"Rules for Investigating and Analyzing Accidents Involving Enterprise Employees\" (GB6442–1986), the following situations are considered indirect causes: (1) Defects in technology and design – issues exist in the design, construction, and use of materials for industrial components, buildings, mechanical equipment, instruments, manufacturing processes, operating methods, maintenance, and inspections. 　　(2) Insufficient training; lack of training, or absence of knowledge or understanding of safe operating procedures. 　　(3) Unreasonable labor organization. 　　(4) Errors in the lack of inspection or guidance for on-site work. 　　(5) There are no safety operating procedures, or they are inadequate. 　　(6) Failure to implement accident prevention measures or doing so inadequately, as well as poor handling of rectifications for potential accident risks. 　　(7) Others. 　　In this case, the workers lacked the relevant knowledge and skills for protecting sewage wells; clearly, insufficient training was an indirect cause of the accident. “\"Inadequate rescue efforts\" reflect a lack of training in emergency response, and it is also an indirect cause of the accident. ““The workers were not wearing personal protective equipment” and “the workers carried out operations in violation of regulations” were the direct causes of the accident. 　5 Before entering the sewage wells of Refinery C for work, gas testing is required; the gases that are typically tested should include (A, B, C). View materials: A. Flammable gases B. Toxic gases C. Oxygen D. Hydrogen E. Carbon dioxide. Reference explanation: After the accident, gas levels in the sewage well were tested; the oxygen concentration was 19.6%, methane content was 2.7%, and hydrogen sulfide content was 850 mg/m3. Methane is a flammable gas, and hydrogen sulfide is a toxic gas; both should be monitored. In confined spaces, oxygen levels also need to be monitored; a normal concentration is generally between 18% and 22%.