2nd conditional or passive?

can anyone answer this for me? I had this question in a book:

1. What would happen if the sky (was / were ) polluted?
my answer was to choose 'were' as it being the correct choice in a contrary to fact 'if' clause.
However i was told that the correct choice would be 'was' because it is passive.
I am confused .... who is correct?

[Tdol]

There's no difference between active and passive IMO with the conditionals. I would say that both forms are correct, though 'were' is preferred by many. If you say 'if I were you', then say 'if the sky were polluted' as well.