The two have been posited:

Lithium can be viewed an antioxidant – correctly or not?, I do not know.

Air pollution can be viewed as oxidative stress.

It’s interesting to search Google Scholar for “lithium antioxidant”.

Lithium by itself is not an antioxidant. It's already oxidized in any bio-available compound, so it can't be used to reduce anything.

But it apparently somehow modulates other systems that help with oxidative stress.