Galvanized steel is steel coated in molten zinc to create a protective layer that prevents corrosion and rust. While this makes the material durable, welding it creates a significant health hazard due to the intense heat. Welding galvanized steel can make you sick, and the primary risk is an acute, temporary condition called Metal Fume Fever. This illness results from inhaling the fumes produced when the zinc coating is superheated.
The Danger: Zinc Oxide Fumes
Welding generates extremely high temperatures, which causes the zinc coating on the steel to vaporize into a gas. This zinc gas then reacts with oxygen in the surrounding air to form very fine particles of zinc oxide (ZnO). These microscopic zinc oxide particles constitute the visible white-gray fume that rises from the weld site.
When these fumes are inhaled, the tiny zinc oxide particles bypass the body’s natural respiratory defenses and settle deep within the lungs. The immune system interprets these inhaled particles as a foreign threat, triggering a systemic inflammatory response. This reaction is mediated by the release of immune signaling proteins called cytokines, which circulate throughout the body and initiate the flu-like symptoms.
The concentration and duration of exposure directly relate to the severity of the body’s reaction. Even concentrations of zinc oxide fume below established regulatory limits can still cause a measurable inflammatory cellular response in the lungs.
Recognizing Metal Fume Fever
The illness resulting from zinc oxide inhalation is known as Metal Fume Fever, though it is sometimes called “zinc chills” or “welders flu.” Symptoms typically do not appear immediately but are delayed, usually starting between four and twelve hours after exposure. This delayed onset means the person feels fine immediately after welding but becomes ill hours later, frequently overnight.
The symptoms closely mimic a severe case of influenza, which is why the condition is often misdiagnosed. Common signs include a sudden onset of fever and chills, muscle aches (myalgia), joint pain, headache, and fatigue. A distinctive symptom that helps distinguish it from a viral infection is a metallic or sweet taste in the mouth, often accompanied by throat irritation.
In most cases, the symptoms peak within the first 24 hours and are entirely self-limiting. Full recovery usually occurs within 24 to 48 hours after exposure has ended. Treatment focuses on rest, hydration, and over-the-counter fever reducers and anti-inflammatories. However, if symptoms worsen, or if the individual experiences chest pain or difficulty breathing, immediate medical attention is necessary.
Preventing Exposure
Preventing exposure to zinc oxide fumes requires a multi-layered approach focusing on engineering controls, preparation, and personal protection. The most effective method involves controlling the fumes at their source before they enter the welder’s breathing zone. This is best achieved through local exhaust ventilation (LEV) systems, which use hoods or movable arms to capture and filter the airborne contaminants right where the welding is taking place.
If working indoors, proper LEV is necessary, but welding outdoors can also provide natural ventilation to help disperse the fumes. Another highly effective preparation step is the mechanical or chemical removal of the galvanized coating from the area to be welded. Grinding the zinc coating off a few inches on either side of the weld joint significantly reduces the amount of fume generated.
When engineering controls are not sufficient, appropriate personal protective equipment (PPE) is required. A simple dust mask is insufficient for protecting against these fine metal oxide fumes. Welders should use a respirator specifically rated for metal fumes, such as a Powered Air-Purifying Respirator (PAPR) or a half-mask respirator with P100 particulate filters.
Are There Chronic Health Effects?
Metal Fume Fever is classified as an acute illness, meaning it is temporary and does not typically lead to long-term lung damage. Individuals recover completely without lasting complications. This temporary nature differentiates it from more serious, chronic lung diseases caused by other welding fumes.
However, repeated inhalation of metal fumes is not without consequence. Repeated, high-level exposure over extended periods without proper protection may lead to persistent respiratory issues like chronic bronchitis or general airway irritation. Furthermore, experiencing the acute illness can temporarily sensitize an individual, making them more susceptible to another episode of Metal Fume Fever if they are exposed again shortly after recovering.