I visited a working ine in the 1960s. I was surprised just how much dust there was in the air - it was like walking into a snowstorm, and you couldn't see more than a few feet ahead of you because of the dust. This came from the stonedust barriers, which were supposed to stop fire spreading in the event of an explosion. They comprised a wide plank fixed horizontally above the roadways, and piled high with stone dust. Some men were employed to do nothing else but top up the stone dust which was constantly blown off by the ventilation. The idea was that in the event of an explosion the stone blew off the plank and formed a curtain of dust which stopped the flame spreading - I've no idea if it worked but I guess they wouldn't have done it if it didn't.

The coal face was relatively clean - the pit I visited was hot rather than wet, and the face was cooled by jets of water, which helped to keep the dust down.

The other thing that really impressed me was the diesel workshops, where fitters were repairing diesel injectors in the ever-present cloud of stone dust.