Dell optiplex 790 mini-tower Owner's Manual page 95

Environmental
Operating
Storage
Airborne contaminant level
–15.2 m to 3048 m (–50 ft to 10,000 ft)
–15.2 m to 10,668 m (–50 ft to 35,000 ft)
G1 or lower as defined by ANSI/ISA-
S71.04-1985
95