The Effect of Avoiding Closed Spaces on the Indoor Environment of Nursery School Rooms during COVID-19 winter

Abstract

This study aimed to clarify the effect of the policy of avoiding closed spaces with poor ventilation for preventing COVID-19 on the indoor environment of nursery school rooms during winter. The measurement survey was conducted in 23 rooms of nine nursery schools in the Tokai region of Japan. We measured the CO2 concentration, temperature, and humidity in 10 min intervals during the winter in 2022. The data collected from 9 a.m. to 3 p.m. on weekdays when the rooms were occupied were analyzed. The results showed that the mean value of the CO2 concentration in the nursery school rooms was below 1000 ppm in 22 of 23 rooms. Besides, we estimated the ventilation rate and found that most rooms exceeded the value per person required to keep the concentration below 1000ppm. The results suggest that the nursery school teachers actively used mechanical and window-opening ventilation. On the other hand, the mean temperature was below 18 °C in 12 rooms and the mean relative humidity was below 40% in 22 rooms. We found that increasing the ventilation volume to avoid closed spaces during winter significantly decreased the relative humidity in the nursery school rooms.