I don't know about that, but it wasn't because
carbon monoxide gave them cancer.
<
https://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=1163&tid=253#bookmark06>
Who sets up a web site called "HealthGuidance.org"
anyway? And who reads it? And tell me if this
is sneaky: it says "16K people like this" -
that's on every page. It's counted for the
entire site.
I accept that diesel exhaust, especially, can
cause serious long term injury to health, maybe
even cancer. But it kills a lot fewer of its
users (not counting the people you mentioned,
and victims of climate change, and vehicle
accidents - okay, maybe don't ignore all those),
and people around them, than cigarette smoke.
Although - that's going to depend on how much
you make a nonparticipant breathe in, of each.
not one person on a bus smoking, for instance,
but one person /not/ smoking. Well, anyway,
smoking isn't coming back. Live with it.
Live without it. (I wouldn't have that
confidence if Donald Trump was a smoker.
In fact, secondary smoke could kill him.
And it might be worth it.)
The unexpected hazard in diesel exhaust is
the sooty particles; until those were considered,
diesel really did seem to be the safer and more
efficient option.