Arsine (AsH₃) is a heavier-than-air (2.7×), colorless, nonirritating gas that is typically odorless but may have a faint odor of garlic or fish. Exposure is via inhalation; it is not absorbed through the skin, nor does it cause skin irritation. Its toxicity results in acute intravascular hemolysis. Arsine is commonly used in the smelting and semiconductor industries, and it is often released accidentally in the production of hydrogen during smelting, refining, galvanizing, soldering, etching, and lead-plating operations.

Whether the release of the gas is accidental or intentional, the mortality rate of inhaling a concentration of 3 ppm or greater is 25%. Upon inhalation, there may be a burning sensation in the chest followed by chest pain; but typically, there are no symptoms at all, leaving the victim unaware that he/she has been exposed.

The length of time between exposure and exhibition of symptoms depends on the concentration and duration of exposure. A delay of 2-24 hours is typical before the onset of any symptoms. Initial symptoms of arsine poisoning include nausea, vomiting, headache, malaise, weakness, dizziness, abdominal pain, flank pain, and dyspnea. Symptoms progress to include hematuria, jaundice, and renal failure.

Precautions: Full-face air-purifying gas mask or SCBA (self-contained breathing apparatus). Standard precautions are recommended for victims (gloves, hand washing, and splash precautions). Decontamination is not necessary in most cases.