Indoor Air Quality Conditions and Respiratory Virus Detections in Elementary Schools-Kansas City, Missouri,...

Respiratory viruses circulate year-round and can spread indoors via inhalation of airborne particles. Effective ventilation and filtration may reduce transmission, particularly in school settings where children and staff spend significant time. This study examines the impact of indoor air quality (IAQ) and ventilation in schools on respiratory virus detection.

During February 27 to March 30, 2023, we assessed the relationship between IAQ and respiratory viruses in two Kansas City, Missouri, elementary schools by collecting bioaerosol samples, student and staff nasal swabs, and monitoring IAQ across 10 rooms (six classrooms, two common spaces, and two nurses' offices). We calculated air changes per hour ( $\text{ACH}$ ) and analyzed viral detections in nasal swabs and bioaerosol samples by high (≥ 1000 ppm) or low (< 1000 ppm) CO₂ concentration in classrooms.

We collected 173 nasal swabs from 100 participants and 30 bioaerosol samples from 10 rooms. Participants were mostly female (68%) and white (60%). Viruses were detected in 90% of bioaerosol and 35% of nasal samples. Four classrooms and both common spaces had the same virus detected in bioaerosol and nasal swab samples. None of the spaces met the CDC recommended $\text{ACH}$ of 5, and only one exceeded ANSI/ASHRAE 62.1-2022 standards for outdoor air supply. During school hours, 83% of classrooms had high average CO₂ concentrations. Classrooms with high CO₂ levels had higher viral detection.

Viral presence was found in bioaerosol and nasal samples with some overlap in concurrently collected samples. Findings suggest a possible connection between high CO₂ levels and virus detection. Improving IAQ and ventilation may reduce respiratory infection risks in schools. However, this study highlights the need to further assess the impact of various environmental modifications on respiratory virus transmission in schools, including determining optimal strategies such as ventilation, filtration, or germicidal ultraviolet energy.