Metal fume fever is an acute febrile illness caused by the inhalation of respirable particles (fume) of zinc oxide. Although metal fume fever is invoked as a generic effect of exposure to numerous other metal oxides (copper, cadmium, iron, magnesium, and manganese), there is little evidence to support this (although inhalation of some of those metals can be associated with pneumonitis or pneumonia). Metal fume fever usually occurs in workplace settings involving welding, melting, or flame-cutting galvanized metal (zinc-coated steel) or in brass foundries. Zinc chloride from smoke bombs can cause severe lung injury, but does not cause metal fume fever.

Metal fume fever results from inhalation of zinc oxide (neither ingestion nor parenteral administration induces this syndrome, although other toxic effects may result from those routes of exposure). The mechanism is uncertain but may be cytokine mediated. It does not involve sensitization (it is not an allergy) and can occur with first exposure (in persons previously naïve to inhaled zinc oxide).

The toxic dose is variable. Resistance to the condition develops after repeated days of exposure (tachyphylaxis) but wears off rapidly when exposure ceases. The ACGIH-recommended workplace exposure limit (TLV-TWA) for respirable size zinc oxide particulate is 2 mg/m³ as an 8-hour time-weighted average with a short-term exposure limit (STEL) of 10 mg/m³, which is intended to prevent metal fume fever in most exposed workers. The NIOSH recommended exposure limit (REL) for total zinc oxide particulate over 10 hours is 5 mg, but with a ceiling limit of 10 mg. Welding on galvanized metal without appropriate ventilation easily can exceed these limits. The air level considered immediately dangerous to life or health (IDLH) is 500 mg/m³.

1. Symptoms typically begin 4-8 hours after exposure with fever, malaise, myalgia, and headache. The white blood cell count may be elevated (12,000-16,000/mm³). The chest radiograph should be normal. Typically, all symptoms resolve on their own within 24-36 hours.
2. Rare asthmatic or allergic responses to zinc oxide fume have been reported. These responses are not part of the metal fume fever syndrome.
3. Pulmonary infiltrates and hypoxemia are not consistent with pure metal fume fever. If present, this suggests possible heavy metal pneumonitis resulting from cadmium or other toxic inhalations (eg, phosgene and nitrogen oxides) or bacterial pneumonia associated with metal working, foundry operations, or welding.

A history of welding, especially on galvanized metal, and typical symptoms and signs are sufficient to make the diagnosis.

1. Specific levels. There are no specific tests to diagnose or exclude metal fume fever. Blood or urine zinc determinations do not have a role in clinical diagnosis of the syndrome.
2. Other useful laboratory studies include CBC. Pulse oximetry or arterial blood gases and chest radiography should be normal in patients with metal fume fever, as compared with other disorders manifesting as acute lung injury.

1. Emergency and supportive measures
   1. Administer supplemental oxygen and give bronchodilators if there is wheezing and consider other diagnoses, such as an allergic response (Table I-17). If hypoxemia or wheezing is present, consider other toxic inhalations (Gases, Irritant).
   2. Provide symptomatic care (eg, acetaminophen or another antipyretic) as needed; symptoms are self-limited.
2. Specific drugs and antidotes. There is no specific antidote.
3. Decontamination is not necessary; by the time symptoms develop, the exposure has usually been over for several hours.
4. Enhanced elimination. There is no role for these procedures.