Originally posted by ThorSanchez That struck me as a little odd. I think that if you don't live in an industrial city in China pollution and haze is equal or less than 50 or 75 years ago.
When I used to live in Philadelphia (1995-2000), on a clear day, I judge the daily pollution level by looking at the blue sky and looking at when that blue turned to brown. On a good day the brown would end about 30 degrees off the horizon, on a bad day it was closer to 45 degrees.
Where I live now, except on certain spring days when the winds would whip up dust, I see blue all the way to the horizon without any brown sky.
I can't say whether that pollution would have an impact on telephoto lenses and distant subjects, but humidity in the air definitely can, and here 30-50% humidity is a very humid day. We're usually closer to 10-15% humidity.