Cause of haze/smoke in US Gulf?

See this image, taken from the afternoon visible (full disk)
GOES shot of the americas.

http://www.fractalfreak.com/astro/0918NA_SNIPPET.jpg

It's been this way on and off since Katrina.

Very bad haze and smoke from NO though east Florida, on out
off the SE US and into the ocean as a diseased tendril of
brown ****.

It's about as bad as I've seen.

I live in WI., and last week a stagnant air pattern brought
this air up to our neck of the woods. Very bad, there were
actually air quality warnings from all the particulates --
something I can never remember happening from years past.

It was disgusting.

Any ideas on the cause? Usually if it's a forest fire the
source is easy to locate ... I can see none here.

-Eric B

PS - Also check out this snippet from same satellite shot.
This time south america. The burning has been long and extreme
this year.

http://www.fractalfreak.com/astro/0918NSA_SNIPPET.jpg