The comparative of "environmentally friendly"

adjectives comparatives

Solution 1:

Google Ngram Viewer shows more environmentally friendly is by far the most common of the two:

Ngram of environmentally friendlier vs more environmentally friendly

This is even more stark for the superlative:

Ngram of environmentally friendliest vs most environmentally friendly

Solution 2:

"more environmentally friendly" is more understandable (understandablier?) to this native speaker from the Northeastern US. However, I would guess that both are technically correct.

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