Suggestions from someone who hasn't used sub mm units in decades and is therefore out of practice: since the first section is supposed to orient us, remove the French =3mm bullet point, you never mention French again as far as I can see, so it's just trivia.
Instead, try to link the first 2 points - maybe express human hair in nm instead of um, so that we can then visualize an angstrom (something most people don't know about) in terms of human hair (something most folks do know). Don't make us convert nm and um our heads.
