This work presents a study of the effect of ventilation rates on the bioaerosols that cause upper respiratory illness. A network of 147 sensors was placed in a pair of dormitories on a college campus to measure carbon dioxide concentrations over two semesters. The concentration results served as input into multi-zone ventilation models of the two buildings, which had different heating, ventilation, and air conditioning (HVAC) systems. The dormitory with a central mechanical ventilation system had, as expected, a higher turnover of fresh air compared to the other, which relied on exhaust fans and infiltration. This well-ventilated building also contained far fewer occupants with recorded upper respiratory illness incidence in comparison to the poorly ventilated building. The central ventilation system increased dorm room ventilation rates by 500%, while decreasing respiratory illness incidence by over 85%. Comparative studies have shown similar findings with increased ventilation reducing incidence of upper respiratory illness by an order of magnitude.