For hospitals and healthcare facilities, indoor air quality is defined by compliance with ASHRAE and other regulatory standards with respect to air change rates, humidity requirements, and pressurization, according to an article on the Consulting-Specifying Engineer website.
Indoor air quality encompasses temperature, humidity, quantity, presence of chemicals and other contaminants and the quality of outdoor air brought inside.
Indoor air quality is especially important in healthcare facilities. Indoor air quality is part of patient satisfaction measurements.
Patient-satisfaction survey results also directly impact funding, so healthcare facilities have focused on reducing their nosocomial infections and increase patient comfort by (among other things) improving indoor air quality.
A Shift in Healthcare Facilities Management
Trauma-Informed Design Transforms Boston Homeless Shelter
Inside One of Healthcare's Most Ambitious Hospital Projects 
Disinfectant Contact Time: The Case for Biofilm Disruption
Texas HHSC Reaches Construction Milestone for Panhandle State Hospital in Amarillo