Kingfish wrote:

I'm confused. You say (he said) vis is better now than in the late
60's/early 70's due to airborne pollution then say vis was far better
in the 50's than it is today.

scratching head

It makes sense to me this way:

Visibility was of a certain quality in the 50's. It got worse in the
60's & 70's. These days, it's better than it was the 60's & 70's, but
not as good as the 50's.

But then again, I've been wrong before! G