Red Sludge and Red, Red Rain

The so-called Red Sludge disaster in Hungary is pretty crazy stuff, no? I mean, not only is it burying its victims, but it is also BURNING them! A little science lesson to help explain all this:

"Red sludge is a byproduct of the refining of bauxite into alumina, the basic material for manufacturing aluminum. Treated sludge is often stored in ponds where the water eventually evaporates, leaving behind a largely safe red clay...."

Wait a minute here. Keep in mind, I was a pretty poor student in the low-level hard science courses I was forced to take as part of my liberal arts education, but bear with me here with this question I have:

Q: The sludge is toxic, until the water evaporates, at which time it's not so toxic. Doesn't that mean that the toxicity went up in the air into the clouds; and when things go up, they tend to come back down?

Someone has a good bead on all this: Mr Peter Gabriel, taking us into the weekend....