Welding joins materials using intense heat to melt parts together. This process is inherently hazardous because the electric arc is an extremely powerful source of light, heat, and harmful emissions. The welding mask, or helmet, serves as the primary barrier against this dangerous output. Operating without this protection exposes the user to immediate, intense radiation and the inhalation of fine particulate matter, leading to acute and chronic health consequences.
The Immediate Danger to Vision
The most immediate consequence of welding without a mask is photokeratitis, commonly known as arc eye or welder’s flash. This is essentially a severe sunburn of the cornea, the eye’s outer layer, caused by intense ultraviolet (UV) radiation from the arc. Even a brief, unprotected glance can damage the corneal epithelium.
Symptoms are typically delayed, emerging four to twelve hours after exposure. The affected individual experiences significant eye pain, often described as feeling like sand trapped in the eye. This pain is accompanied by excessive tearing, redness, and photophobia, an extreme sensitivity to light.
The welding arc also emits infrared (IR) radiation, which penetrates deeper, affecting the lens and retina. While UV causes acute pain, repeated IR exposure contributes to the long-term risk of developing cataracts, which is a clouding of the eye’s lens. The intense visible light component can also temporarily overwhelm the retina, causing temporary blindness and eye fatigue.
Skin Exposure and Thermal Injury
The welding arc generates intense radiation, posing a serious threat to any exposed skin. Unprotected skin suffers a severe form of sunburn due to the high output of UV radiation. This radiation is powerful enough to cause second-degree burns in minutes.
The skin is also highly vulnerable to thermal injury from the physical byproducts of the welding process. Molten metal droplets, known as spatter, are ejected from the weld pool and cause immediate, localized thermal burns. Hot slag, the non-metallic residue, can also cause painful burns and scarring upon contact. Welders who neglect protective clothing risk both radiation burns from the arc and direct thermal injury from these superheated materials.
Acute Inhalation Hazards from Welding Fumes
Welding generates a complex mixture of fine particulate matter (fumes) and gases, which are acutely hazardous when inhaled without respiratory protection. Fume composition varies based on the base metal and filler materials, containing vaporized metals like zinc, copper, manganese, and iron oxide. Gaseous byproducts, such as ozone, carbon monoxide, and nitrogen oxides, are also created by the heat interacting with air and shielding gases.
A common acute illness is Metal Fume Fever, a flu-like syndrome often triggered by inhaling zinc oxide fumes when welding galvanized steel. Symptoms, including fever, chills, headache, nausea, and muscle aches, typically manifest several hours after exposure and resolve within 24 to 48 hours. This condition is an acute systemic reaction to the metal oxides.
Inhaling these fumes and gases immediately irritates the respiratory tract, causing coughing, throat dryness, and shortness of breath. High concentrations of nitrogen oxides and ozone can cause acute chemical pneumonitis. Welding in confined or poorly ventilated spaces also risks suffocation, as inert shielding gases like argon and carbon dioxide can displace breathable oxygen.
Long-Term and Chronic Health Risks
Repeated, unprotected exposure to welding fumes and radiation leads to cumulative and chronic health issues. Long-term inhalation of fine metallic particles causes chronic respiratory illnesses, including chronic bronchitis, reduced lung function, and pulmonary fibrosis, which is the scarring of the lung tissue. The persistent inflammation and damage from the particulates can also lead to occupational asthma.
Welding fumes have been classified by the International Agency for Research on Cancer (IARC) as a Group 1 carcinogen, meaning they are definite cancer-causing agents. This classification links long-term exposure to an increased risk of lung cancer. Furthermore, repeated exposure to the arc’s UV radiation is associated with an increased risk of ocular melanoma.
Chronic exposure to certain heavy metals in the fumes can also damage the central nervous system. Specifically, inhaling manganese, a common component in mild steel welding fumes, can lead to Manganism. This neurological condition presents symptoms similar to Parkinson’s disease, including tremors, difficulty with motor control, and balance disorders.