How Long does it take for Sodium Nitrite to oxidize?

[thinkkank]

My SN came in the mail and I want to test it but I'm worried that if I open the bag the SN will oxidize into sodium nitrate which is harmless. when exposed to oxygen. how long does it take?

 

[Science Is Scary]

It might be because I'm terrible at chemistry, but this question is disturbingly hard to research. The best I can find is that it happens "very slowly."

I looked up the source of that claim, The Merck Index, and it didn't give any numbers either. I did many searches in Google Scholar and couldn't find any relevant experiments. I'm beginning to wonder if the source of this information doesn't exist online. Perhaps it was a story passed on by oral tradition from ancient Greeks.

I'm emotionally invested in this question now, so I hope someone else can find a better answer. If my short bus arrives before then, I suspect I'll haunt this thread and curse the three people who know how to use the search function on this forum.