No air-cooled computer is completely safe in a shop environment. The AIO machines are perhaps a tad more durable than tower machines, as there is typically only one way air flow - from the bottom of the screen/case to the top. Most of the time, they're depending on convection to move the air in the computer; when the CPU or video subsystem started burning watts, then they ramp up the internal fans, keeping with the convection airpath (from bottom to top).

One of the things to remember about computers in shop environments is to turn them off, open the covers and blow them out with filtered, dry air at a low pressure. Or use a Freon computer duster can.