Hazard Overview: Regardless of the type of welding process, fumes always present an inhalation hazard. Fumes are actually pieces of metal that were originally released into the air as a gas but which condense into microscopic particles. Fumes are generated by the heat of the weld and are composed of metals, metal oxides and other compounds emitted from the base metal, the electrode or the flux material. All welding processes produce fumes even if they are not visible. Fumes are so small that they are often able to penetrate deep into the lung tissues. Fumes from welding often contain iron oxide that, when breathed for a long period of time, can cause siderosis, a benign type of lung disease caused by dust. High concentrations (acute exposures) of welding fumes can cause irritation of the nose, throat and lungs. Chromium—present in stainless and high alloy steels—may increase the risk of lung cancer. Other harmful fume components may include lead, mercury, molybdenum, nickel, tin, titanium, vanadium and zinc. Nitrous oxides, carbon monoxide and other products (from liners, residual cleaners or stored chemicals) may also be present. Metal fume fever is a flu-like illness often suffered by welders. Chronic or long-term exposures to toxic metals contained in welding fumes can lead to serious health problems, such as central nervous system problems from manganese or bone changes from fluorides. Chronic exposure to cadmium can cause fluid in the lungs, emphysema and kidney damage.
Radiation from welding falls into three groups of wavelengths: visible, ultraviolet and infrared. All three are hazardous to the welder and to anyone else who might enter the area without appropriate protection. Burns from hot metal or ultraviolet light can damage both the eyes and skin. Fire, explosion and noise are also included in welding hazards.
Precautions: As with any hazardous exposure, the best precaution is to prevent it in the first place. Ventilation can significantly reduce exposures to hazardous fumes and gases. Ventilation can be outdoor prevailing winds, dilution ventilation produces by fans or air movers or local exhaust ventilation such as an air hood.
Accidental contact can result when equipment is suspended for any substantial period of time such as during lunch, shift change or overnight. All electrodes must be removed from the holders and the holders carefully located so that accidental contact cannot occur. Machines also must be disconnected from their power sources.
Routine air monitoring can verify that precautions such as ventilation are adequate and resulting exposures are acceptable. Air monitoring for flammable atmospheres is also critical for successful fire prevention; welding should be done only in non-flammable atmospheres.
Torch valves not in use for a substantial period of time, such as lunchtime, shift change or overnight, must be closed and the gas supply positively shut off. Secure cylinders and machinery.
Physical shields and barriers can reduce the risk of metal or radiation burns to both workers and passersby.
Personal protection varies based on the type of welding process and the contaminants expected. In general, minimal personal protection for welding includes eye, face, head, hand, and neck protection. Hand protection should be insulated for both heat and electricity. Safety glasses or goggles are primary eye protection, welding hoods, face-shields, or visors are secondary eye protection. Primary eye protection should be worn under secondary eye protection.
Protective eyeshade numbers should be selected based on the welding process (oxy-acetylene welding and cutting requires a minimum Shade No. 4-5.) Arc welding requires a minimum of Shade 10.
Respirators are often worn, as are ventilation hoods. Air supply or fume type respirators should be used.
Other PPE such as protective aprons, footwear and hearing protectors are also often required.
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