TA-23-C051 – The Indoor Air Quality of Classrooms With and Without Portable Air Purifiers: A Pilot Study ✓ Most Recent

This study aimed to investigate the effect of portable air purifiers on the indoor air quality in classrooms. In this pilot study, the research team monitored air quality parameters in twenty classrooms from three school buildings of a school district located in the state of Nebraska in Spring 2022. The classrooms were assigned into four groups, with 85% of classrooms assigned to experimental conditions (35% to Treatment 1, 30% to Treatment 2, 20% to Treatment 3), and 15% assigned to the control condition. Treatment 1 consisted of air purifiers with High Efficiency Particulate Air (HEPA) filters, and Treatment 2 had HEPA filters along with Active Carbon. Treatment 3 had HEPA and Active Carbon filter along with Germicidal Ultraviolet (GUV) technology. The control group used a device without any filter, which served as a placebo. The measured parameters were carbon dioxide (CO2), particle counts (PN), total volatile organic compounds (TVOC), ozone (O3), carbon monoxide (CO), relative humidity (RH) and temperature (T). Particle counts were measured over a 24-hour period incorporating both occupied and unoccupied time for the students in the classrooms. CO2, RH, and temperature values were acquired throughout the semester through loggers installed in the classrooms. Other parameters: TVOC, ozone, and CO were measured for 20-25 mins duration in each classroom during unoccupied time. Continuous CO2 data was used to compute ventilation rates, and statistical analyses were used to compare classroom indoor air quality across treatment and control conditions. During the occupied time, the mean cumulative particle counts were statistically significantly lower in treatment groups as compared to control groups for all particle sizes. However, during the unoccupied period, statistically significant treatment effects were seen in smaller particle counts but not in larger particle sizes. The effect of air purifiers on TVOC concentrations in classrooms is inconclusive. Ozone values inside all buildings across all treatment/control groups were lower than outdoor values and below the thresholds i.e. C 0.1 ppm as per the recommended exposure limit (REL) by the National Institute of Occupational Safety and Health (NIOSH). The next phase of this project will explore the connections between indoor air quality and student academic performance. The study is ongoing with measurements occurring in additional (over 200) classrooms across the state of Nebraska. With student-level data, we will be able to better understand the impact of air purifiers on the improvement in air quality and students’ academic performance and attendance.