Polluted Fantasy World

[Jamesvance64]

http://www.giantitp.com/forums/showthread.php?t=274523

I might be good for you to check out the link at the top, since it might give you a better idea about what i want from it all. (if not, oh well)

Suppose a world's skies were actually green and very acidic. Rainstorms are acidic enough to dissolve, the surface is covered in oceans of acids. This is what has happened to the fantasy world that ive been designing for a game im creating (for D&D).

A professor proposed that Nickle in the atmosphere would cause he green hues in the sky and would cause some type of sterility in animals when they got it in their bodies, as well as lung cancer. Would it still be breathable? would it work in coloring the sky green, rather than blue? would it cause acid storms?