disease-free vs hygienic

disease-free

adj
  • free of disease, not having, carrying, or suffering from any disease. 

hygienic

adj
  • Pertaining to hygiene; clean, sanitary. 

  • Whose expansion is guaranteed not to cause the accidental capture of identifiers. 

How often have the words disease-free and hygienic occurred in a corpus of books? (source: Google Ngram Viewer )