Answers to the Recertification Questions for Occupational Disease Hazard Assessment Professionals

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Answers to the Review Questions for Occupational Disease Hazard Assessment Professionals 1. When using the analogy method to identify occupational disease hazard factors, it is necessary to determine the similarities between the project under consideration and the analogous projects, taking into account factors such as the similarities in the general characteristics of the projects, the similarities in occupational health protection facilities, and the similarities in environmental conditions. 2. Employers exposed to occupational disease hazards shall entrust a vocational health technology service institution with the appropriate qualifications to conduct tests for occupational disease hazard factors at least once a year ； Employers exposed to serious occupational disease hazards shall engage a occupational health technical service institution with appropriate qualifications to conduct an evaluation of the current status of occupational disease hazards at least once every three years. 3. Employers who engage in operations involving highly toxic substances shall conduct inspections for occupational poisoning hazards in such workplaces at least once a month ； An evaluation of the effectiveness of controls against occupational poisoning hazards should be conducted at least once every six months. 4. Harmful factors in the workplace include oxygen deficiency or **toxins; when their concentrations are high enough to be life-threatening, protective equipment such as isolated air respirators or oxygen respirators should be used. 5. For construction projects involving new construction, expansion, or renovation, as well as projects for technological upgrading or the introduction of new technologies, if there is a risk of occupational disease hazards, the project owner shall submit a pre-assessment report on such hazards to the department in charge of work safety supervision and management during the feasibility study phase. 6. The effectiveness of general ventilation depends on two factors: the volume of air exchange and the airflow pattern within the workshop. 7. The Maximum Allowable Concentration (MAC) is the highest allowable exposure limit established for chemical substances that have significant irritant, asphyxiating, or central nervous system depressant effects, and can cause severe acute damage. 8. In general, the harmful factors in the production process include chemical factors, physical factors, and biological factors. 9. For construction projects with serious occupational disease hazards, the pre-evaluation report on such hazards shall be submitted to the work safety supervision and management department for review; the design of the occupational disease prevention facilities shall also be submitted to this department for examination. After the completion of the occupational disease prevention facilities, the work safety supervision and management department shall organize an inspection to verify their compliance. 10. When the exposure concentration exceeds the PC-TWA and reaches the PC-STEL level, the duration of a single exposure session should not exceed 15 minutes, the number of exposures per workday should not exceed 4, and the interval between consecutive exposures should be no less than 60 minutes. 11. After a construction project is completed and trial operation is required, the occupational disease prevention facilities installed as part of it must be put into trial operation simultaneously with the main structure of the project. The trial operation period shall be no less than 30 days and no more than 180 days. 12. The construction unit is the responsible party for the installation of occupational disease prevention facilities in construction projects ； The project owner shall organize relevant experts to review the preliminary evaluation report and be responsible for its authenticity and legality. 13. Role of occupational health and safety technical service institutions: First, they provide technical support to **regulatory authorities** ； The second is to provide technical services to employers ； Third is to provide health services for workers. 14. The occupational exposure limits for chemical hazards include three categories: time-weighted average permissible concentration, short-term exposure permissible concentration, and maximum permissible concentration. 15. Bag filters belong to the category of filtration-type dust collectors. 16. The first level of the three-level prevention principle in occupational health is etiological prevention (eliminating and controlling occupational disease hazards at their root). 17. The costs associated with the installation of occupational disease prevention facilities for construction projects should be included in the project’s budget. Such facilities must be designed simultaneously with the main structure of the project, constructed at the same time, and put into use once construction is completed. 18. Different occupational hazard factors cause varying degrees of harm to the human body. For example, dust can cause pneumoconiosis, chemical agents can lead to occupational poisoning, and noise can result in occupational deafness. 1. What is a pre-evaluation of occupational disease hazards? Answer ； Pre-assessment of occupational disease hazards involves conducting predictive health-related analyses and evaluations, during the feasibility study phase, of construction projects that may pose occupational disease risks. These assessments examine the potential occupational disease-causing factors, the extent of those risks, their impact on workers’ health, as well as the necessary protective measures. This process helps determine the feasibility of such projects in terms of occupational disease prevention and control, providing a scientific basis for the classified management of occupational disease hazards. 2. What are the stages and forms in which industrial toxins exist during the production process? Answer ； Industrial toxins present in the production process include raw materials, auxiliary materials, intermediate products, finished products, by-products, inclusions, or waste; sometimes they can also originate from thermal decomposition products. It exists in the production environment in solid, liquid, gaseous, or aerosol form. 3. Briefly describe under what circumstances employers exposed to occupational disease hazards should promptly engage a qualified occupational health technical service institution to conduct an evaluation of the current status of such hazards? Answer: Employers exposed to occupational disease hazards shall promptly entrust a vocational health technology service institution with the appropriate qualifications to conduct an assessment of the current status of such hazards in any of the following situations: 1. When applying for a vocational health and safety license for the first time, or when applying for a renewal of the license after its expiration date ； 2. Occurrence of occupational disease hazard accidents ； 3. **Other circumstances specified by the State Administration of Work Safety. 4. Briefly describe the evaluation principles for exhaust hoods. Answer: 1. Has the exhaust method been reasonably determined in accordance with the design principles of the exhaust hood? Whether dust and harmful gases at production stations can be effectively controlled depends on the ventilation method. Generally speaking, these principles are: “Sealed” (as airtight as possible), “Proximate” (close to the source of harmful gases and dust), “Unobstructed” (ensuring sufficient exhaust volume), “Appropriate” (the exhaust hood matching the emission of dust and toxins), and “Convenient” (easy to operate). 2. Whether the control wind speed and the locations of control points are reasonably determined based on site conditions, and whether these serve as the basis for designing and calculating the ventilation volume. Depending on the production processes and procedures, as well as the methods of exhaust ventilation and the types of harmful gases and dust emitted, it is necessary to determine an appropriate control wind speed for each situation in order to effectively manage dust and harmful gases. Generally, the control point for dust is the farthest point (or the most unfavorable point) where dust can scatter; the control point for harmful gases is the edge of the working surface. 3. Determine through actual measurement whether the exhaust volume meets the required design specifications. 5. Into which categories can toxicological prevention measures be broadly divided? Answer: Preventive measures (replacing toxic and highly toxic materials with non-toxic or less toxic ones, modifying processes, and implementing closed systems in the production process) ； Control measures (general ventilation, local ventilation) ； Purification methods (combustion, condensation, absorption, adsorption) ； Individual protective measures. 6. Briefly describe the contents of a report on the evaluation of the effectiveness of controls for occupational disease hazards? Answer: 1. General Introduction ； 2. Project overview and trial operation status ； 3. Investigation and evaluation of the overall layout and equipment layout ； 4. Investigation, detection, and evaluation of occupational disease hazard factors ； 5. Investigation and evaluation of occupational disease hazard prevention facilities ； 6. Investigation and evaluation of personal protective equipment against occupational diseases ； 7. Investigation and evaluation of building hygiene and auxiliary rooms ； 8. Investigation and evaluation of occupational health management ； 9. Analysis and evaluation of occupational health surveillance ； 10. Conclusion ； 11. Suggestions. 7. Briefly describe the main contents of the engineering analysis in the pre-assessment of occupational disease hazards for construction projects? Answer: The main contents include: project overview, site selection, overall layout, production process, production equipment and its layout, materials and products in the production process, as well as building hygiene. 8. How to determine whether a construction project may or may not pose occupational disease hazards? Answer: It is necessary to determine whether a construction project may or may not pose risks of occupational diseases based on the \"Classification Catalogue of Occupational Disease Hazard Factors\". If a construction project does not contain any of the occupational disease hazard factors listed in this catalogue, it can be concluded that such a project will not pose risks of occupational diseases; conversely, if it does contain such factors, it can be determined that the project may pose such risks. 9. Briefly describe the applications of excess multiples? For coal dust, the PC-TWA is 4 mg/m3 for total dust and 2.5 mg/m3 for inhaled dust. The short-term (15 min) exposure concentrations for total dust and inhaled dust were measured to be 9 mg/m3 and 5 mg/m3 respectively. How should the excess factor be used for evaluation? Answer: 1. The application of excess factor control is used for chemicals and dusts for which no PC-STEL has been established, in order to prevent excessive fluctuations in their short-term exposure levels. Within the limits set by the PC-TWA, the excess factor for chemical substances (depending on the value of the PC-TWA) is 3 to 5 times the PC-TWA ； The dust excess factor is 2 times the PC-TWA. 2. Evaluation of the excess factor: (1) The short-term (15 min) exposure concentration for total dust was 9 mg/m3; the excess factor was 9/4 = 2.5, which is greater than the allowed value of 2, so it does not meet the requirements regarding the excess factor. (2) The short-term (15 min) exposure concentrations for total dust were 5 mg/m3 each, which equals the limit value; thus, the requirement regarding this limit value is met. 10. Briefly describe the eight-character guideline for dust prevention and control. What are the main measures for preventing and controlling dust? Answer: The eight-character principle for dust control is “replace, water, seal, ventilate, protect, manage, educate, and inspect”” ； Among them, “ leather” means reforming the manufacturing process by adopting new technologies ； Water: that is, wet working ； Closed: That is, to seal off the dust source ； Wind: That is, ventilation for dust removal ； Protection: refers to personal protection ； Management: That is, to strengthen maintenance and management by establishing various systems ； Teach: That is, to carry out publicity and education ； Inspection: This refers to conducting physical examinations on employees as well as testing the dust concentration in the production areas. Main dust control measures: wet operations, enclosed ventilation for dust removal, and purification of dust-containing gases. 11. What are the prohibitions on practice for occupational health technology service agencies and their full-time technical personnel when carrying out occupational health technology services? Answer: Occupational health technical service institutions and their full-time technical personnel shall not engage in the following acts when providing occupational health technical services: (1) Disclosing the technical secrets and trade secrets of their clients ； (2) Falsifying, altering, transferring, or leasing qualification certificates ； (3) Engaging in technical service activities beyond the scope permitted by the qualification certificate ； (4) Issuing false or inaccurate occupational health technical reports ； (5) Subcontracting of occupational health technical service projects ； (6) Unauthorized modification or simplification of procedures and related content for occupational health technical services ； (7) Employing unfair competitive practices to deliberately belittle or defame other occupational health technical service institutions ； (8) Other illegal acts stipulated by laws and regulations. Full-time technical personnel shall not work for more than two occupational health technical institutions at the same time. 12. Briefly describe the main data that should be collected for the evaluation of the effectiveness of occupational disease hazard control in construction projects? Answer: 1. The pre-assessment report on occupational disease hazards, and the review opinions of the competent administrative department regarding the project during the feasibility study and design phases. 2. Technical documents for the project, mainly including: (1) Overview of the construction project ； (2) Materials and products in the production process ； (3) Production process ； (4) Production equipment ； (5) Occupational disease hazard prevention measures taken ； (6) Relevant design drawings ； (7) Data on on-site occupational health inspections ； (8) Information on occupational health examinations for workers. 3. Status of the project’s trial operation. 4. **, local, and industry-related laws, regulations, standards, and guidelines regarding occupational health. 5. Various documents related to occupational health management. 13. What are the key evaluation points for ventilation ducts? Answer: Does the design of the ventilation ducts meet the design requirements, and are their layout and direction reasonable? ； Whether the design wind speed and air volume of the ducts can meet the requirements for exhaust volume as well as for transporting harmful gases and dust through the ducts ； Has the ventilation system for multiple exhaust points taken into account the balance of resistance and the required ventilation volume for each branch duct? ； It is necessary to check whether the measured wind speed and air volume in the ducts meet the required design specifications. Occupational hazards refer to the collective term for all elements or conditions that arise or exist during the process of work and in its environment, and which may have an adverse effect on the health, safety, and working capacity of occupational workers. Dust dispersion: It is a concept that indicates the size of dust particles; the smaller the dust particles that make up the dispersed phase, the higher the dispersion degree ； Conversely, it is lower. It is expressed as a weight percentage based on the grouping of dust particles by diameter; that is, it is the percentage of the weight (in grams) of dust particles with a diameter of d (within a given diameter group) within the total weight (in grams) of the sampled dust, and this value represents the dispersion degree of that group. Pneumoconiosis: A systemic disease characterized by diffuse fibrosis (scarring) of the lung tissue, resulting from long-term inhalation of occupational dusts during work activities and their accumulation in the lungs. Engineering control technical measures: These refer to the use of engineering techniques and methods (such as sealing, ventilation, cooling, isolation, etc.) to control the concentration or intensity of occupational hazard factors that are generated or present during the production process, thereby reducing the concentration or intensity of harmful substances in the working environment to levels within the limits permitted by occupational health standards. The situation and characteristics of occupational disease hazards in our country: ① A large number of people are exposed to occupational disease hazards, resulting in a high incidence of illness ； ②Occupational disease hazards are widespread across various industries, with a particularly severe impact on small and medium-sized enterprises ； ③Occupational disease hazards are highly mobile, with severe transfer of risks ； ④Occupational diseases are characterized by latency and delayed onset, and their hazards are often overlooked. Classification of occupational disease hazard factors: Source classification: Hazardous factors generated during the production process (chemical factors, physical factors, biological factors) ； Harmful factors in the work process ； Hazardous factors in the production environment. Classified according to the Ministry of Health’s \"Classification Catalogue of Occupational Disease Hazard Factors\": dust, radioactive substances (ionizing radiation), chemical substances, physical factors, biological factors, hazard factors causing occupational skin diseases, hazard factors causing occupational eye diseases, hazard factors causing occupational ear, nose, throat, and oral diseases, hazard factors for occupational tumors, and other occupational disease hazards – a total of ten categories. List of occupational diseases: There are a total of 10 major categories and 115 types of legally recognized occupational diseases in my country: ①Pneumoconiosis; ②Occupational radiological diseases; ③Occupational poisoning; ④Diseases caused by physical factors; ⑤Diseases caused by biological factors; ⑥Occupational skin diseases; ⑦Occupational eye diseases; ⑧Occupational ear, nose, throat, and oral diseases; ⑨Occupational tumors; ⑩Other occupational diseases. Occupational exposure limit: It is the most important component of occupational health standards, referring to the allowable level of exposure that workers can be subjected to on a repeated basis during their professional activities, without causing any harmful effects on the health of the vast majority of those exposed. Noise: From a subjective perspective, any unwanted interfering sound can be considered noise. In terms of physical properties, noise is an irregular and chaotic combination of sound waves with various frequencies and intensities. All sounds generated during the production process can be referred to as occupational noise. Facilities for protecting against occupational disease hazards refer to the collective term for equipment, facilities, devices, and structures used to eliminate or reduce the concentration or intensity of occupational disease hazard factors in the workplace, to prevent and minimize the damage or adverse effects of these hazards on workers’ health, and thus to protect workers’ health. Engineering analysis: By conducting a systematic and comprehensive analysis of the engineering and health-related characteristics of a construction project, it is possible to understand the project’s technological features, process flow, and level of health protection. This provides a basis for identifying the types, nature, spatial and temporal distribution of potential occupational disease hazards, as well as their impact on workers’ health, for selecting key evaluation factors, and for determining the evaluation units. Occupational health surveys: Occupational health surveys mainly include investigations into the basic conditions of occupational health, as well as hygienic assessments of the production process, working processes, and working environment. Evaluation units: Based on the characteristics of the construction project and the requirements for evaluation, the production process, equipment layout, or workplace is divided into several relatively independent parts or areas. Basic principles for the assessment of occupational disease hazards: Implement the policy of giving priority to prevention and combining prevention with control, apply classified management to construction projects, and carry out comprehensive management ； Adhering to the principles of science, fairness, objectivity, and truthfulness, it ensures the independence of the evaluation process and eliminates the influence of non-technical human factors ； Following the principles of risk assessment, a comprehensive analysis is conducted of the potential occupational disease hazards associated with the construction project ； The evaluation of control effectiveness should be carried out under full production capacity and normal operating conditions ； Comply with **relevant quality management regulations. Analogical method: By conducting occupational health surveys on projects that are identical or similar to the project under evaluation, testing the concentrations (intensities) of occupational disease hazards in the work environment, and analyzing relevant documents and technical materials related to the project under evaluation, it is possible to infer the types and levels of occupational disease hazards associated with that project. This enables risk assessment of such hazards and prediction of the effectiveness of the protective measures that will be implemented. Evaluation of the effectiveness of controls against occupational disease hazards: Before the completion and acceptance of a construction project, a comprehensive assessment is conducted regarding the occupational disease hazard factors in the workplace, the degree of these hazards, the measures taken for protection against occupational diseases and their effectiveness, as well as any health impacts. Pre-evaluation plan: It is a technical document that provides specific guidance for the pre-evaluation of occupational disease hazards in construction projects. It should be prepared after thorough study of relevant materials, preliminary engineering analysis, and on-site investigations. Guided by the principles of scientificity, practicality, and relevance, it outlines the characteristics of occupational disease hazards associated with the project, and specifies the key aspects, scope, methods, and quality control measures for the evaluation. Main contents of the pre-assessment report on occupational disease hazards: General introduction, overview of the existing enterprise, engineering analysis, analogous investigations, identification and analysis of occupational disease hazard factors, analysis of protective measures against occupational disease hazards, assessment of occupational disease hazards, supplementary measures for controlling occupational disease hazards, conclusions and recommendations. The three-level prevention principle of occupational health: etiological prevention, preclinical prevention, and clinical prevention. Purpose of the Law on the Prevention and Control of Occupational Diseases: To prevent, control, and eliminate occupational disease hazards, combat occupational diseases, protect the health and related rights of workers, and promote economic and social development. Occupational diseases refer to illnesses that occur among workers in enterprises, institutions, and individual economic organizations as employers, as a result of exposure to dust, radioactive substances, and other toxic and harmful factors during their occupational activities. The prevention and control of occupational diseases adhere to the principle of giving priority to prevention and combining prevention with control. A mechanism is established featuring responsibility on the part of employers, supervision by administrative authorities, industry self-discipline, employee participation, and social oversight, in order to implement classified management and comprehensive control. Employers that pose risks of occupational diseases shall install a bulletin board in a prominent location ； For work positions that pose serious occupational health hazards, warning signs and Chinese warning instructions should be placed in prominent locations there ； At workstations where highly toxic substances are present or generated, information cards regarding these highly toxic substances must be placed in prominent locations in accordance with the \"Specifications for Providing Information on Occupational Health Hazards at Workstations Involving Highly Toxic Substances\" (GBZ/T203). Employers shall, in line with the \"Regulations on the Supervision and Management of Occupational Health Monitoring for Employees\", establish occupational health monitoring records for workers and keep them properly stored for the specified period. Occupational health surveillance records should include information related to the worker’s occupational history, exposure history to occupational disease hazards, results of occupational health examinations, outcomes of any interventions taken, as well as other personal health data related to occupational diseases. Employers who use toxic substances in the workplace shall apply to the work safety supervision and management department for an occupational health and safety license in accordance with relevant regulations. A occupational health technology service agency refers to an institution that provides technical services such as pre-assessments of occupational disease hazards for construction projects, evaluations of the effectiveness of measures taken to control such hazards. It also offers employers services including testing for occupational disease hazards, assessments of the current situation regarding these hazards, and evaluations of the effectiveness of protective equipment and supplies. When the work safety supervision and management department conducts reviews of pre-assessment reports on occupational disease hazards, examines the design of occupational disease prevention facilities, and carries out inspections for the completion of such facilities in construction projects, it shall randomly select experts from an expert pool to participate in these reviews, examinations, and inspections. For each task, no fewer than 3 experts shall be randomly selected from the expert pool. For construction projects with occupational disease hazards, the project owner shall entrust a design unit with the appropriate qualifications to prepare a specialized design document for occupational disease prevention facilities. **Special management is implemented for operations involving radiation, highly toxic substances, and hazardous dusts. 13. A certain workshop uses a diluent, with a consumption rate of 3 kg per hour. Main components of the diluent: xylene 30%, ethyl acetate 50%, ethanol 20%. Calculate the minimum air flow rate required to ensure that the air in the workshop meets health standards. Serial Number Chinese Name Occupational Exposure Limit (mg/m3) MAC PC-TWA PC-STEL 1. Xylene – 50 100 2. Ethyl acetate – 200 300 3. Ethanol – – – Answer: According to the calculation formula L = M/YS – Y0 ； Wherein: L = ventilation volume, m3/h ； M – Amount of harmful substances generated. Mg/h ； Occupational exposure limits specified in the YS-health standards ； mg/m3 ； Y0 – The background concentration of this harmful substance in fresh air, in mg/m3. The xylene consumption M is: 3×1000×1000×30% = 900000 mg ； The consumption of ethyl acetate, M, is: 3×1000×1000×50% = 1500000 mg ； Based on actual production conditions, the occupational exposure limit is determined using the PC-TWA value; specifically, the value for YS (xylene) is 50 mg/m3, and that for YS (ethyl acetate) is 200 mg/m3. Y0≈0, and the calculation yields 900000/50 – 0 + 1500000/200 – 0 = 18000 + 7500 = 25500 m3/h, which is equivalent to 25500/3600 = 7.08 m3/s. Therefore, the minimum air flow rate required to ensure that the air in the workshop meets health standards is 7.08 m3/s. 14. A local exhaust ventilation system is shown in the figure below; the structures of the three local exhaust hoods are identical. It is known that the total air volume of the system is L=2 m3/s, and the static pressure at point A is PAj = -100 Pa ； Static pressure at point B, PBj = -150 Pa ； The static pressure at point C, PCj, is -100 Pa. Calculate the exhaust volume for each exhaust hood. file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image002.jpg Answer: According to the calculation formula Q= ； Where: Q – exhaust volume of the exhaust hood, m³/h ； Area of the cross-section measured for the F-cover connection pipe, in m2 ； Pj–Static pressure at the measured section, Pa ； ρ – density of the gas inside the pipe, kg/m3 ； u – flow coefficient, which depends only on the structural shape of the exhaust hood. According to the given conditions, FA=FB=FC ； Therefore: QA + QB + QC = 2. QA = QC. Hence: QA = QC = 0.62 m³/h ； QB=0.76m3/h. 15. A company plans to build an automobile production line with an annual output of 50,000 cars. The line includes a stamping workshop, a welding workshop, a painting workshop, and an assembly workshop. The raw material for this project is steel plate, while the main auxiliary materials include coatings (with benzene derivatives and solvent gasoline as key components), welding wires (containing elements such as Mn and Cu), etc. The production process flow in the stamping workshop is as follows: material preparation (uncoiling and blanking) → stamping and forming (various stamping lines) → inspection (using special inspection tools) → warehousing. The main production process flow in the welding shop is: assembly → welding → repair welding → inspection → application of sealant → body adjustment. (1) Briefly describe the types of main occupational disease hazards in the stamping workshop and the welding workshop, as well as the stages at which they arise (10 points). (2) Briefly describe the occupational disease prevention measures that should be taken in the stamping workshop and the welding workshop (10 points). Answer: 1. Types of the main occupational disease hazards in the stamping workshop and the welding workshop, as well as the stages where they arise. (1) Types of the main occupational disease hazards in the stamping workshop and the stages where they arise: ① Types of the main occupational disease hazards: noise, vibration. ②Stages where the main occupational disease hazards arise: Stamping production operations (material preparation, stamping forming) (2) Types of main occupational disease hazards in the welding workshop and the stages where they arise ① Types of main occupational disease hazards: A. Dusts: Welding fumes ； B. Chemical substances: manganese and its compounds (manganese fume, manganese dust, manganese compounds), benzene derivatives, gasoline ； Nitrogen oxides. C. Physical factors: high temperature, noise. D. Hazardous factors causing occupational eye diseases: ultraviolet rays. E. Occupational hazard factor for occupational tumors: benzene. F. Ionizing radiation. ②Stages where the main occupational disease hazards are generated: A. Assembly, vehicle adjustment (noise) ； B. Welding, repair welding (welding fumes, manganese and its compounds, nitrogen oxides, ultraviolet rays) ； C. Apply sealant (benzene compounds, gasoline) ； D. Inspection (ionizing radiation). 2. Occupational disease prevention measures to be adopted in the stamping workshop and the welding workshop (1) Occupational disease prevention measures to be adopted in the stamping workshop ① Noise control A. Source control: The main methods include using equipment with low noise and low vibration levels; installing vibration-damping foundations when setting up noise-generating equipment, and equipping devices that produce significant noise with noise-reducing devices. B. Transmission route control: a. Reasonable diagram layout. For example, separate high-noise workshops from those with lower noise levels as well as living areas, to prevent mutual interference ； For particularly intense noise sources, they can be located in areas far from the plant, allowing the noise to attenuate naturally to the greatest extent possible with distance. b. Control noise in the production workshop. In addition to selecting low-noise processing procedures and production equipment, it is also necessary to implement “zoning of quiet and noisy areas” in the layout of production equipment to prevent mutual interference. Moreover, noise sources of the same type in various workshops—such as hydraulic presses—can be grouped together in a single hydraulic machinery room. This not only prevents the excessive dispersion of sound sources and the expansion of noise pollution, but also facilitates the implementation of acoustic measures for centralized treatment. c. Make full use of natural features such as slopes, shrubs, and lawns wherever possible. d. Utilize the directivity of sound sources to control noise. C. Personal protection: When no measures can be taken at the sound source or along the transmission path, or when acoustic technical measures fail to achieve the desired effect, it is necessary to provide workers with suitable personal protective equipment, such as noise-blocking earplugs, protective earmuffs, and noise-protective helmets. ②Vibration control: A. Reduce the excitation intensity of the vibration source. B. Cut off the path of vibration propagation or weaken the vibration along that path. C. Vibration-resistant measures can be taken for buildings or equipment subjected to vibrations. ③High-temperature control: A. Reduce the thermal effects of heat sources, i.e., thermal insulation ； B. Discharging a large amount of heat ； C. Local cooling. ④Labor process control: A. Labor organization, systems, and work schedules should be reasonable ； B. The labor intensity and production quotas should be scientifically arranged; for instance, the assigned tasks should be compatible with the physical conditions of the workers. ⑤Ergonomics should be given full consideration, with efforts made to eliminate or reduce excessive strain on certain organs or systems, as well as prolonged poor postures or the use of inappropriate tools, such as strain on the eyes. ⑥Production environment control: A. Fully consider natural environmental factors, such as shielding from solar radiation during hot seasons. B. The factory building or its layout should be reasonable to ensure adequate lighting and smooth ventilation. C. Avoid air pollution in the working environment, etc. (2) Occupational disease prevention measures to be adopted in the welding workshop: ① Control of toxic chemicals: A. Preventive measures against chemical toxins. a. Replacing highly toxic benzene derivatives with non-toxic or low-toxic materials is the fundamental measure to control the hazards of toxic substances ； b. Reform the process. Try to choose processes that generate little or no toxic substances during production ； c. The sealing of the production process is key to preventing toxic substances from escaping during production ； d. Isolation operation. B. Chemical toxin control measures. Take ventilation and detoxification measures. C. Chemical toxin purification measures. The toxic gases emitted must pass through appropriate purification devices to meet environmental protection emission standards. ②Control of productive dusts: A. Dust source control and isolation. Keep the welding dust generated during the production process within a certain range to prevent it from spreading, thereby enabling the ventilation and dust removal system to function at its best. B. Ventilation and dust removal system. ③Ultraviolet rays: Wear personal protective equipment such as welding goggles. ④High-temperature control: A. Reduce the thermal effects of heat sources, i.e., thermal insulation ； B. Ventilation to remove heat ； C. Local cooling. ⑤Labor process control: A. Labor organization, systems, and work schedules should be reasonable ； B. The labor intensity and production quotas should be scientifically arranged; for instance, the assigned tasks should be compatible with the physical conditions of the workers. ⑥Ergonomics should be given full consideration, with efforts made to eliminate or reduce excessive strain on certain organs or systems, as well as prolonged poor postures or the use of inappropriate tools, such as strain on the eyes. ⑦Production environment control: A. Fully consider natural environmental factors, such as shielding from solar radiation during hot seasons. B. The factory building or its layout should be rational to ensure adequate lighting and smooth ventilation ； Toxic and non-toxic operations are not arranged in the same workshop, etc. C. Avoid air pollution in the working environment, etc.