As we grow to better understand the microorganisms in built environments – and what dynamics support their survival – we will be able to design and engineer buildings for better health.Our built environments matter. Research shows that 85% of our time is spent indoors, and we are the main source of bacteria in indoor environments. Some of the bacteria and viruses sourced from humans are pathogenic – they can cause disease.Not all microorganisms are bad for us. In fact, only about 1% of known microbial species are harmful. It’s true that that’s not the full picture, given that microbiologists have only been able to define an estimated 1% of the potential microorganisms out there. Nevertheless, the 1% of the known 1% enable infectious diseases that kill an estimated 16 million people a year.