These systems have been integrated over the decades with improvements in filtration processes, and in recent years with a resurgence of ultraviolet germicidal irradiation (UVGI) applications, to form a triad of technologies used by engineers to provide acceptable IAQ in health care facilities.
Although insightful, Nightingale could not have foreseen all the mounting challenges facing health care facilities in this new millennium. Today's escalating fears, from TB epidemics to bioterrorism with aerosolized anthrax spores, have generated even greater demands on this technology triad to provide a healthy indoor environment. That environment must be conducive both to patients (to nurture well-being during diagnosis treatment, and recovery), and to health care workers (to reduce exposure to patient pathogens and to limit sensitization to allergenic substances).