When I was a kid living in England. We lived near London and without any exaggeration I would walk to school which was only a few blocks away but you literally couldn't see your hand in front of your face. I'd have to run my hand along the hedges and walls and count the streets because of what they called fog but actually it was smog from all the coal being burned. Everyone burned it.
My mom would wash the bedsheets and they'd be nice and white. She'd hang them outside to dry and they'd come back in a grey colour.
No wonder people died of cancer.