Vassili, like Thomas said we are currently conducting tests on the copper. I can't imagine that it will be much of an issue. Copper oxidization is a good thing when you are talking about corrosion. The patina that is formed (a thin shell of copper rust) will actually protect the rest of the copper.
The Statue of Liberty has been standing out in the elements since 1886 and has only lost .005" to its exterior according to this site : http://www.professionalroofing.net/a....aspx?A_ID=526