found in several alloys used in very specialized applications such as in aircraft, rockets and missiles, spacecrafts, and nuclear
reactors. Acute beryllium poisoning can result
from a less than 50 day exposure
to its concentrations as low as 20 micrograms (millionth of a gram) per cubic meter of ambient air. It causes usually-fatal berylliosis by inhalation, and produces its subacute and chronic forms from skin contamination
as a hazardous pollutant
, beryllium's maximum concentration
is set generally at 0.1 micrograms per cubic meter of ambient air.