During the third century AD, the Greek physician Galen of Pergamon first described the “miasma” theory of illness, holding that infectious diseases such as cholera, chlamydia and the Black Death were caused by noxious clouds of “bad air”. The theory is discredited today, but such ideas die hard.
August 12, 1865 The Shoulders of Giants — Today in History
chazrothmsg 
I dunno. I’m not a climate alarmist, but my gut tells me there’s something to it. The air is not as good as I was when I was a kid. It’s much worse than when my parents were kids. I don’t think the sky is as clear as it used to be.
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When the EPA was established [1972] the air was thick with smog in the West Coast and Northeast Corridor. That smog is now virtually non-existent.
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That’s good. I’ve noticed, since I was little (90s,) the smog over the City of Portland (Maine) has become progressively thicker, especially on overcast and/or muggy days. Which is insulting when you consider that Maine used to be one of the more environmentally friendly states.
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