634 One of the all-time greatest Q drops. Read every word.... (media.greatawakening.win) posted 3 years ago by purkiss80 3 years ago by purkiss80 +635 / -1 159 comments download share 159 comments share download save hide report block hide replies
I have had to cede to r/yudsfpbc comment above, seems they know more than me. Sorry if it was misinformation. I should have looked this up first. Good article though explaining. https://www.smithsonianmag.com/smart-news/story-real-canary-coal-mine-180961570/
Used up until 1986... The last of them was retired in 1999.