Actually you need ventilation also for the actual humans.
A common "standard" for mines/tunnelling is:
3 Cubic meters/minute per worker
4 cubic meters/minute per diesel HP (calculated on the max power output of the engines)
Electric vehicles (battery powered) are usually not considered as they normally represent a fraction of the power involved in the construction/digging.
The large machines that are electrically powered (via cable/wire) are not included as they do not produce exhaust fumes nor particles/vapours, but they may be considered in some cases for the amount of heat they produce.
