In a single family residence, a space between floor joists is enclosed with galvanized steel sheet and is used as a return air duct for the furnace. Can non-metallic sheathed cable in air that is not identified as LS be routed along the joists within the space ?

In a single family residence, a space between floor joists is enclosed with galvanized steel sheet and is used as a return air duct for the furnace. Can non-metallic sheathed cable in air that is not identified as LS be routed along the joists within the space ?