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It's an interesting article from 2004; might not be reading it right but seems like this one from 2020 is less optimistic about hydroxyl radicals (OH) breaking down PFOA in the atmosphere. https://pubmed.ncbi.nlm.nih.gov/31978654/

Your same link notes that the majority of PFOA is not broken down in the atmosphere and points to "wet and dry deposition" mostly, which sounds like it's being dropped down to Earth remaining as PFOA.

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> It's an interesting article from 2004; might not be reading it right but seems like this one from 2020 is less optimistic about hydroxyl radicals (OH) breaking down PFOA in the atmosphere. https://pubmed.ncbi.nlm.nih.gov/31978654/

That's an interesting paper. If so, multiply the atmospheric time by 2-4.

> Your same link notes that the majority of PFOA is not broken down in the atmosphere and points to "wet and dry deposition" mostly, which sounds like it's being dropped down to Earth remaining as PFOA.

Yes. That doesn't affect the "half life" here.

In the end, not much PFOA ends up in the atmosphere in the first place, and most precipitates out to less convenient places where it lives longer. Of the stuff resident in the atmosphere, it does break down on human timescales, at least...

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