Unless federal mining regulations have changed tremendously in my couple of decades of absence, that can't be true. Only those miners directly involved in making a major air change are allowed to be underground during a major air change in the Brookwood coal mines. Ventilation plans may vary elsewhere. I doubt they have changed that drastically in the gassiest mines in the country in Brookwood. Unions play a major role in compiling those ventilation plans. It's not always about money and insurance. Safety is a major interest to the Brookwood coal miner. Allow him to educate you on that.