SFA, sometimes I just wonder at the fact that history is recorded directly now, beginning a bit before my own generation -- film rather than just a verbal description...1930, you found an early film with sound!
I copied off a couple of comments, below the film, people whose family members worked in the mines...
"No gloves no helmets no safety gear. My dad lost part of his hand. And dies of black
Lung. I can’t believe we lived through these times. It wasn’t living it was existing. Thank his they all closed."
"I am the proud granddaughter and great granddaughter of South Wales coal miners. My great grandfather died of black lung leaving my grandfather to earn for his mother and seven siblings - he went down pit at the age of 14."