Inhalation of zinc-containing smoke generally originates from industrial processes like galvanization, primarily affecting manufacture workers. In addition, military smoke bombs contain zinc oxide or zinc chloride, making soldiers a group in which several cases of inhalation of zinc-containing fumes were described. For example, Homma and colleagues reported a case of two soldiers who developed adult respiratory distress syndrome (ARDS) respectively. Another soldier was exposed to concentrated zinc chloride for several minutes during military training . He also developed ARDS 48 h after exposure. After tracheal intubation and mechanical ventilation for eight days, he left the hospital, and four months after the incident he returned to work without any respiratory disorder . There are a few additional reports of related incidents with smoke bombs having similar effects on the respiratory tract .
However, in none of the incidents there was unequivocal evidence that zinc was the main cause for the respiratory symptoms. Not only was no information about the concentrations available, but also the inhaled smoke contained several other ingredients besides zinc chloride. In addition, zinc chloride is generally caustic, so the effects could have risen from the specific properties of the compound, rather than being a direct effect of zinc intoxication.
The most widely known effect of inhaling zinc-containing smoke is the so-called metal fume fever (MFF), which is mainly caused by inhalation of zinc oxide. This acute syndrome is an industrial disease which mostly occurs by inhalation of fresh metal fumes with a particle size