english: Humans in the developed world spend more than 90 percent of their lives indoors, where they breathe in and come into contact with trillions of life forms invisible to the naked eye: microorganisms.
non_english: Ljudi u razvijenom svetu provode vise od 90% svog života u zatvorenom prostoru, gde dišu i dolaze u kontakt sa trilionima različitih životnih formi koje su nevidljive golim okom mikroorganizmima.