@ x7 and AC
Lead II Oxide (PbO)
Hence all the safety equipment (HEPA etc.) and the frequent blood tests, though most of us who grew up when leaded fuels were used were exposed to far more lead from car exhausts.
The more immediate health issues were from dealing with the heat involved with blast furnaces, the molten rock they produce and other elements that were in the rock and might be cooking off like nickel and chromium and stuff.
That poor 286 was built like a tank, though I can't remember if it was a Compaq or something crazy like a Packard Bell...