Brian Kunde has a useful look at the science writing of the Lovecraft biographer L. Sprague de Camp, as part of a review of his The Heroic Age of American Invention. Others include…

The Story of Science in America.

The Great Monkey Trial (the trial that Lovecraft sometimes refers to).

Darwin and His Great Discovery.

Great Cities of the Ancient World.

The Evolution of Naval Weapons (for the U.S. government, as a course textbook).

The Ape-Man Within.

He was working alongside Sagan and Asimov, in the popular science / debunking superstition field.

Earlier, in Astounding (July 1938), his non-fiction “Language for Time Travelers” surveyed the difficulties a time traveller would encounter with pronunciation, semantics and vowel shifts. Put together with his “non-fiction radio scripts for Voice of America”, if extant, could there be a public domain audiobook there for someone to tackle?