Pressurized Filter system

How does it work?  
The breathing air of the excavator operator, first passes through a suitable filter combination, then this clean air is slightly pressurized and flows towards the cabin.
The small amount of overpressure reduces the intrusion of harmful substances in the cabin.
Air conditioning is mandatory, because the operator can not open any windows or doors, furthermore this clean air is, temperature wise, not conditioned. In the cold season the excavator's heater can cope with the cold air, but during the summer (and, inside an all glass cabin, summer lasts longer than just 2 months) temperature inside the cabin can rise uncomfortably high.
Air conditioning is really a must.
Click to enlarge.