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In safety technology, factors that affect production safety (such as electric shock, flammability, and explosiveness) are referred to as hazard factors, while those that affect human health are called harmful factors. The harmful factors that affect human health during welding can be divided into two main categories: physical harmful factors and chemical harmful factors. Physical harmful factors include welding arc light, electromagnetic waves, thermal radiation, and radiation ； Chemical hazards include welding fumes and harmful gases, among others. This article discusses the occupational hazards associated with welding caused by these harmful factors and the corresponding protective measures. I. Implement the Work Safety Law and the Law on the Prevention and Control of Occupational Diseases to promote the legalization of safety and health protection measures in welding work. China began to enforce the Law of the People’s Republic of China on the Prevention and Control of Occupational Diseases on May 1, 2002, and the Work Safety Law of the People’s Republic of China on November 1, 2002. A regulatory framework for occupational safety and health has now been established, with these two laws as its core. 1. Strictly enforce the two laws to promote the institutionalization of occupational protection in welding. The Work Safety Law stipulates that production and business entities must comply with relevant laws and regulations on work safety, strengthen work safety management and responsibility systems, improve work safety conditions, and ensure safe production. It stipulates that workers have the right to be informed about hazardous factors and emergency measures, as well as the right to work-related injury insurance and compensation for injuries or deaths. The Law on the Prevention and Control of Occupational Diseases applies to activities related to the prevention and control of occupational diseases within the territory of the People’s Republic of China. As defined in this Law, an occupational disease refers to a disease that occurs to workers in enterprises, institutions, and individual economic organizations (collectively referred to as employers) during their occupational activities, as a result of exposure to dust, radioactive substances, and other toxic and harmful substances. It is stipulated that the list of occupational diseases shall be established, amended, and published by the health administrative department of the State Council in conjunction with the labor security administrative department of the State Council. In the list of statutory occupational diseases in China, published in 2002 by the Ministry of Health and the Ministry of Labor and Social Security, welding-related occupational diseases such as welder’s pneumoconiosis and photokeratitis were officially included. Additionally, occupational diseases that may arise from welding work were listed, including poisoning by manganese and its compounds, carbon monoxide poisoning, occupational radiological diseases, photodermatitis, and metal fume fever. Therefore, it should be clear that the \"welding profession\" is one in which occupational diseases can occur; as such, welding employers must implement the Law of the People’s Republic of China on the Prevention and Control of Occupational Diseases. 2. Provisions of the Law on the Prevention and Control of Occupational Diseases: The Law on the Prevention and Control of Occupational Diseases requires employers that pose risks of occupational diseases to \"install notice boards in prominent locations to display rules and regulations as well as operating procedures related to the prevention and control of occupational diseases\", as well as \"the results of tests for occupational disease hazards in the workplace\". In accordance with these regulations, bulletin boards must be installed in arc welding workplaces as required by law, to inform workers that long-term exposure to welding fumes can lead to the occupational disease of welder’s pneumoconiosis. These bulletin boards should also outline the ventilation and dust removal measures in place, as well as the relevant rules and regulations, as well as the concentrations of welding fumes detected in the workplace. However, investigations show that many welding employers currently fail to comply with the aforementioned regulations as required by law. The Law on the Prevention and Control of Occupational Diseases also stipulates that: \"When concluding an employment contract with workers, employers shall truthfully inform them of the potential occupational disease hazards and their consequences that may arise during work, as well as the measures for preventing and controlling such diseases and the related benefits, and these details must be included in the employment contract; concealment or deception is prohibited.\" At present, many organizations also fail to enforce this requirement in the labor contracts they sign with welders, as required by law. The Law on the Prevention and Control of Occupational Diseases sets out detailed regulations on various aspects, including workplace health requirements, protective measures and equipment, occupational health training, occupational health examinations, as well as the reporting and treatment of occupational diseases. It should be emphasized that the existence of harmful factors affecting human health during welding is an objective fact that cannot be ignored or concealed. There is no need to feel anxious or fearful; by strictly enforcing the \"Work Safety Law\" and the \"Law on the Prevention and Control of Occupational Diseases\" and by taking appropriate protective measures, it is possible to ensure the health of welding workers as well as safe production. Relevant departments and organizations should \"abide by the law strictly and enforce it rigorously\" to promote the legalization of occupational protection measures for welders. II. Hazards of Welding Fumes and Protection Against Welder’s Pneumoconiosis 1. Hazards of welding fumes to human health Welding fumes are generated during arc welding, when the high temperature of the arc causes liquid metal and slag to heat up and evaporate. Once these high-temperature vapors leave the area surrounding the arc, they are rapidly oxidized and condensed into small solid particles or agglomerated solid particles, which then remain suspended in the air as welding fumes. Comprehensive and in-depth explanations regarding the properties, composition, morphology, and chemical structure of welding fumes from various types of welding materials are provided in the book \"Welding Health and Safety\" compiled by Committee 8 of the Welding Society; therefore, no further details are given here. In the past, there was controversy regarding the degree of harm caused by welding fumes. By the 1980s, due to an increase in the incidence of this disease among welders in certain workplaces, a series of studies were carried out through collaboration between institutions such as the Institute of Occupational Health of the Chinese Academy of Preventive Medicine, Dalian Shipyard, Jiangnan Shipyard, Gansu Provincial Health and Epidemic Prevention Station, the Institute of Occupational Health of the Ministry of Railways, and Qiqihar Vehicle Factory. Through investigations into the incidence of the disease, clinical research, and animal experiments, and particularly through autopsy analyses of welders who died from welder’s pneumoconiosis, it was confirmed that long-term exposure to welding fumes containing substances such as flux 422 and flux 507 can affect the respiratory function of the human body, cause fibrosis in lung tissue, and damage the health and working capacity of welders. Therefore, on November 5, 1987, the Ministry of Health, the Ministry of Labor and Personnel, the Ministry of Finance, and the All-China Federation of Trade Unions jointly issued the \"Regulations on Revising the List of Occupational Diseases and the Procedures for Handling Patients with Occupational Diseases,\" in which \"welder’s pneumoconiosis\" was officially designated as an occupational disease. The subjective symptoms in patients with welder’s pneumoconiosis include coughing, coughing up black sputum, chest tightness, and shortness of breath. Lung capacity is reduced, and chest X-rays of patients with stage I welder’s pneumoconiosis show irregular small shadows or roundish small shadows. The average length of service at which welder’s pneumoconiosis develops is around 15 to 20 years. Due to the large number of welders who began working in factories in China in the 1950s, the late 1970s to the 1980s were a period of high incidence of welder’s pneumoconiosis. Between 1975 and 1977, the former Sixth Ministry of Machinery inspected more than 3,000 welders, and it was found that 3.69% of them suffered from welder’s pneumoconiosis ； In 1983, after 20 years of ongoing observation at Dalian Shipyard, it was found that among 743 welders, 10.63% suffered from welder’s pneumoconiosis ； In 1987, a survey was conducted among 660 workers in the truck workshop of the Qiqihar Vehicle Factory, and it was found that 13.18% of them suffered from welder’s pneumoconiosis. In surveys conducted in the 1980s on the incidence of welder’s pneumoconiosis, it was also evident that the incidence was higher in the cold regions of the north and lower in the southern regions. This is because in cold weather in the north, workshops keep their doors and windows closed for long periods, resulting in poor natural ventilation; therefore, welding workplaces in northern regions should pay more attention to protective measures. Since the 1980s, the incidence of welder’s pneumoconiosis has declined due to the turnover of welders and improvements in ventilation and dust removal conditions in welding workplaces in some large enterprises. However, due to the large number of welders who entered the industry in the late 1980s, if proper protective measures are not taken, there is a concern that a period of high incidence of welder’s pneumoconiosis might occur again around 2010. According to the \"Analysis of the Incidence of Pneumoconiosis in China in 2003\" published by Yin Yu from the Institute of Occupational Health Control at the Chinese Center for Disease Control and Prevention in October 2005, 198 cases of \"welder’s pneumoconiosis\" were reported across various regions in 2003. Moreover, this is an incomplete statistic; the actual number of patients is certainly higher than this. This serves as another warning to us. 2. Effective preventive measures against welding fumes To eliminate the harm that welding fumes pose to human health, the most effective protective measure is to improve ventilation and dust removal in welding workplaces. This includes overall ventilation in the workshop, air exchange in narrow working areas, and smoke and dust removal at welding stations. After extensive investigations and experimental studies conducted by institutions such as the Institute of Occupational Health of the Chinese Academy of Preventive Medicine, the **Standard for Hygienic Requirements of Welding Dust in Workshop Air (GB16194—1996)** was established. This standard is based on the requirement set by health regulations, which states that the incidence of welder’s pneumoconiosis should not exceed 0.5 per thousand after working in an environment with a welding dust concentration as specified. It sets the maximum allowable concentration of welding dust in workshop air at 6 mg/m3. In other words, after implementing ventilation and dust removal measures in the welding workshop, the concentration of welding dust in each cubic meter of air within the workshop shall not exceed 6 mg. This is the only standard for checking whether the ventilation and dust removal in the workshop are up to standard. According to investigations, many welding workshops currently fail to meet this requirement, and efforts should be made to achieve it. As for the development and use of \"dust-free and low-toxicity welding electrodes\" and \"dust-free flux-cored wires,\" I believe they can only serve as secondary supplementary measures, as there is no practical effectiveness in this regard either domestically or internationally (my views on the development of dust-free and low-toxicity welding materials were detailed in the forum on \"Welding Environment and Health and Safety\" organized by this journal). III. Hazards and Protection Against Harmful Gases in Gas Shielded Welding: In addition to welding fumes, gas shielded welding using CO2 produces harmful gases such as carbon monoxide, while TIG welding and plasma arc welding generate harmful gases such as ozone. 1. Hazards of harmful gases in gas shielded welding: The carbon monoxide generated during CO2 gas shielded welding arises primarily from the decomposition of carbon dioxide under the high temperature of the arc. Carbon monoxide has a very strong affinity for hemoglobin, the protein in human blood that carries oxygen. Therefore, once carbon monoxide enters the blood through the alveoli, it quickly binds to hemoglobin to form \"carbonyl hemoglobin\", preventing hemoglobin from performing its normal function of carrying oxygen. This leads to a lack of oxygen in the body’s tissues, resulting in poisoning. At present, in China, CO2 gas shielded welding accounts for more than 20% of the total welding workload nationwide; in the container industry, this figure exceeds 90%, while in some key shipbuilding factories it is over 60%. Therefore, attention must be paid to the occupational hazards and protection measures associated with CO2 gas shielded welding. In conditions with poor ventilation, not only was the concentration of welding fumes above the permissible level, but the carbon monoxide concentration also reached 64.20 mg/m3, which is more than twice the maximum allowable concentration of 30 mg/m3 specified by health standards. Moreover, as working hours increase, the carbon monoxide concentration may rise above 100 mg/m3, and the level of \"carboxyhemoglobin\" in welders’ blood approaches the range associated with mild carbon monoxide poisoning. After implementing ventilation measures with a wind speed of 0.5 m/s, both the concentrations of welding fumes and carbon monoxide fell within the allowable ranges specified by health standards. Therefore, ventilation and protective measures must be taken when using CO2 gas shielded welding. During TIG welding and plasma arc welding, due to the high temperature in the arc zone and intense ultraviolet radiation, oxygen in the air undergoes high-temperature photochemical reactions to produce ozone (O3). When ozone is inhaled into the body, it primarily irritates the respiratory and nervous systems, causing symptoms such as chest tightness, coughing, dizziness, general weakness, and loss of appetite; in severe cases, pulmonary edema and bronchitis may occur. Therefore, **the maximum allowable concentration of ozone in workshop air as specified by health standards is only 0.3 mg/m3. 2. Countermeasures for protecting against harmful gases in gas shielded welding: Measurements taken in five factories in China showed that when using manual tungsten inert gas welding to weld aluminum and aluminum-magnesium alloys, the ozone concentration in the air at the work site ranged from 1.48 to 12.42 mg/m3. In cases of plasma arc cladding and plasma arc spraying, the ozone concentration was between 7.5 and 65 mg/m3 – levels that are all **above the maximum allowable concentrations specified by health standards. The protective measure is to implement effective ventilation to ensure that the ozone concentration in the air near the welder’s breathing zone is 1300 μm, infrared radiation accounts for 38%, near-infrared radiation with wavelengths of 780–1300 μm accounts for 31%, visible light with wavelengths of 400–780 μm accounts for 26%, and ultraviolet radiation with wavelengths of 200–400 μm accounts for 5%. The intensity of ultraviolet rays generated by TIG welding is 10 to 30 times that of conventional shielded metal arc welding, while the ultraviolet intensity of plasma arc welding can be 30 to 50 times higher than that of shielded metal arc welding. The luminosity of the visible light from a welding arc is 10,000 times greater than the level that the human eye can tolerate normally. Such intense visible light will burn the retina, causing photoreactive retinitis. At this time, pain in the eyes will be felt, the visual field will appear blurred, and there will be a central scotoma; it takes some time for these symptoms to resolve. If exposed repeatedly over a long period, it will gradually lead to a decline in vision. The damage to the eyes caused by infrared rays in the welding arc is a chronic process. Prolonged exposure of the eye’s lens to excessive infrared radiation reduces its elasticity, makes it difficult to adjust focus, and leads to a decline in vision. In severe cases, it can also cause clouding of the lens, impairing vision. After a day of work as a welder, if one feels heat in their eyes, it is usually due to the absorption of excessive infrared radiation. When ultraviolet rays from the welding arc reach the eyes, it causes inflammation of the cornea and conjunctiva, resulting in \"photophthalmia\". It is an acute condition that causes stinging in both eyes, redness and swelling of the eyelids along with spasms, tearing, and sensitivity to light. The symptoms can last for 1–2 days, and they will gradually improve with rest and treatment. It should be emphasized that many articles discussing the damage caused by welding arc light to the eyes focus on photophthalmia, while paying insufficient attention to the chronic damage to vision caused by visible light, especially infrared light. In recent years, many regions and enterprises have observed that some skilled middle-aged welders are unable to fully utilize their skills at the peak of their careers due to declining vision. This is a loss for both individuals and society. 2. Protection against welding arc light (1) To protect against the hazards of welding arc light, it is essential to use welding filters (black glass) of qualified quality ； Second is to enhance individual awareness of protection. (2) The standard **\"Protective Gear for Welding Eyes and Faces (GB/T 3609—1994)\”** sets very specific and clear requirements regarding the \"ultraviolet transmittance,\" \"visible light transmittance,\" and \"infrared transmittance\" of welding filters. It also specifies requirements for the refractive power deviation and parallelism of these filters. Only welding filters that meet all the specifications outlined in GB/T 3609—1994 may be used. Furthermore, it is important to note that some low-quality welding filters available on the market (black glass) can only protect against visible light and ultraviolet rays; their protection against infrared rays is poor, and this can damage eyesight. Therefore, companies must never opt for cheap low-quality welding filters. (3) Welders should enhance their awareness of personal protection; when using welding filters, they must check the product certification as well as the test certificates regarding their ability to filter ultraviolet and infrared rays, and refuse to use welding filters without such certifications. V. Protection against other hazard factors. The above has discussed in some detail several of the most significant welding-related occupational hazards and their prevention measures; due to space constraints, only a brief overview is provided for other hazard factors and their corresponding protective measures. 1. Dust and harmful gases from carbon arc gas gouging: Since asphalt is currently used as the binder in the carbon rods employed in carbon arc gas gouging, the harmful gases generated during this process contain benzopyrene, which is highly toxic and carcinogenic. Additionally, a large amount of dust is produced, so effective ventilation and dust removal measures are necessary. 2. Regarding metal fume fever: This condition among welders occurs most frequently after welding galvanized steel sheets or steel coated with zinc-rich primers. Welders inhale zinc-containing welding fumes during the day, and at night their body temperature rises, reaching 38–39°C; they then sweat and feel weak overall. The symptoms improve by the next day, and generally no special treatment is required. But repeated episodes should be prevented to avoid straining physical strength and health. Therefore, when welding on zinc-rich primers or welding galvanized steel sheets, it is necessary to strengthen ventilation and dust removal measures, and dust masks should be worn if required. 3. Regarding manganese poisoning among welders, during China’s First Five-Year Plan period, enterprises built with Soviet assistance used large quantities of weld rods based on a Soviet-style manganese oxide slag formula; as a result, the incidence of manganese poisoning among welders was relatively high, which had a significant impact on society and led to the belief that welders are prone to manganese poisoning. In fact, China phased out high-manganese oxide welding electrodes after 1960, and subsequent health checks of welders showed that there were very few cases of manganese poisoning. As early as 1983, through numerous experiments, the author confirmed that manganese in the welding fumes generated by the calcium-titanium type K422 electrode and the low-hydrogen type K507 electrode exists in the form of spinel, specifically MnFe2O4, rather than in the form of oxides such as MnO or MnO2. This provided a theoretical explanation for why the use of K422 and K507 electrodes results in less risk of manganese and its oxide poisoning. The issue of welder manganese poisoning should only be a concern when welding high-manganese steel. 4. Regarding electromagnetic pollution, in the past, focus was placed on the pollution caused by high-frequency electromagnetic fields; for example, when high-frequency oscillators are used to initiate welding processes such as TIG welding and plasma arc welding, protective measures such as shielding for the operators must be implemented. In recent years, both domestically and internationally, there has been attention paid to the effects of low-frequency and extremely low-frequency electromagnetic fields on human health. The range of low frequency and very low frequency is 0–300 Hz, which includes a large number of electrical devices that use 50 Hz alternating current, such as AC welding machines, electric furnaces, induction heating devices, copper plating lines for welding wires, and drying ovens for electrodes and fluxes. The effects of low-frequency electromagnetic fields on human health remain a hot topic of research in medicine. It is preliminarily believed that they can reduce the body’s immune capacity and have adverse effects on the nervous system. Precautionary measures include avoiding resting near welding machines, electric furnaces, drying ovens and other such equipment while working, and not wrapping the welding cable around the body during operation. VI. Promote welding automation and the adoption of new technologies to eliminate occupational hazards associated with welding. The protective measures discussed above are, in a sense, passive safeguards for the current state of welding operations, and they are certainly necessary at present. However, in the long term, efforts should be made to promote welding automation and the adoption of various new technologies in order to achieve green welding and eliminate occupational hazards associated with welding. (1) Promote the mechanization and automation of welding to replace shielded metal arc welding, including expanding the use of submerged arc welding, advancing automated welding equipment for gas-shielded welding, and promoting automatic welding using manipulators and robots. (2) Vigorously develop various new welding technologies and materials that are pollution-free or produce less pollution, such as promoting the use of friction stir welding and laser welding. Of course, laser welding lacks the pollution factors associated with arc welding, but it introduces new protection issues that should be studied simultaneously. Another issue that deserves attention is the fact that in the past, it was considered a trend to use gas shielded welding with flux-cored wires as a replacement for manual shielded metal arc welding. However, the amount of welding fumes and harmful gases generated in gas shielded welding with flux-cored wires is greater than that in shielded metal arc welding. Professor Chen Jiaben and others in China’s shipbuilding industry have argued that it does not meet the requirements of green welding. In recent years, attention has been paid to \"using active-coated solid wires in conjunction with digital inverter welders,\" which holds great promise for achieving welding with high current, high efficiency, low smoke and dust, and low spatter; this is considered a future development direction.