Advised by Dr. Josephine Lau

Indoor air quality and thermal environmental variables were measured in 55 classrooms in the mid-western United States spanning a full academic year. The studied air quality and environmental factors included carbon dioxide, temperature, relative humidity, particle count concentration, air velocity, formaldehyde, total volatile organic compounds, carbon monoxide, nitrogen dioxide, and ozone. Carbon dioxide and Particulate matter concentrations were measured for a four-day measurement period. Then one-day, two-day, and four-day average concentrations were calculated which were then compared statistically to figure out an appropriate measurement period for these air quality variables. Kruskal Wallis test and Wilcoxon test were used to compare the groups and confirm statistical differences. It was found that one-day CO2 and particulate measurements can provide acceptable values when compared to the multiple day measurements, however, this one-day measurement should be repeated every season to capture seasonal differences in indoor air quality. The air quality variables were also compared between Fall and Spring academic terms in school as well as between heating and non-heating seasons. Mean ventilation rates were found to be 25% higher in heating season while relative humidity, TVOC, ozone, carbon monoxide, and nitrogen dioxide were found lower in the heating season as compared to the non-heating season (although the difference in concentrations of CO and NO2 does not have any engineering significance). This research will provide information to school districts, facility managers, and researchers/engineers considering implementation of air quality measurement plans in a cost-efficient way, this research will also provide a reference for comparing seasonal differences in classrooms and other similar indoor environments.