I think it isn't a case of "nobody knew" so much as "everybody was in deep denial". Black lung was long known along with the effects of poor air as not good for

I think it isn't a case of "nobody knew" so much as "everybody was in deep denial". Black lung was long known along with the effects of poor air as not good for your health. I have noticed a chain of rationalization cropping up a lot with preventable human health crises - often on a generational time scale. The sequence seems to be similiar to an ironic reshuffled subsection of stages of grief. 1. Bargining: "Yeah it is bad but is better than the alternative." (It makes money/keeps us from freezing to death.) 2. Acceptance: "It is a neccessity now." (Most of our industrial and personal exonomy is dependent on it.) 3. Denial: "It can't be harmful!" 4. Anger: "How could we know that it was bad?"