Dell Precision 3520 Owner's Manual page 81

Altitude Specifications
(maximum)
Operating 0 m to 3048 m (0 ft to 10,000 ft)
Non-operating 0 m to 10,668 m (0 ft to 35,000 ft)
Airborne G1 as defined by ISA-71.04–1985
contaminant level
Technical specifications 81