What is the test for "sufficiently serious" deprivation under the Eighth Amendment?

In determining whether a deprivation is sufficiently serious within the meaning of the Eighth Amendment, "the circumstances, nature, and duration" of the deprivation must be considered. Johnson v. Lewis, 217 F.3d 726, 731 (9th Cir. 2000). An occupational hazard is "sufficiently serious" under the Eighth Amendment only when it is exacerbated by an additional factor: for instance, the presence of defective machinery in the prison workplace will not, alone, violate an inmate worker's Eighth Amendment rights, but a machine whose defect is known and which the prisoner must use anyway, may. Morgan, 465 F.3d at 1046-1047.