Which preposition to use with rarefies

as Occurrences 1%

As we walk on through the shining morning, we ourselves seem to grow rarefied as the air.

in Occurrences 1%

The airs of the avenue de l'Opéra in Paris, and, too, of the rue de Rivoli in Papeete, were rarefied in this simple spot to the impulses and experiences of her childhood in the groves and on the beaches of her beloved island.

Which preposition to use with  rarefies