A study on indoor air quality at daycare centers using IoT environmental sensors

Indoor air quality (IAQ) is a major concern at daycare centers, due to the weaker immune system of children. Although IAQ is typically measured in accordance with the ISO-16000 standard, environmental sensors have recently become widely used due to their ability to consistently monitor air quality at a lower cost. In this study, We installed IoT sensors indoors and outdoors at ten daycare centers to measure PM(PM2.5, PM10), CO2, temperature, and humidity, as well as window opening-closing sensors to identify ventilation behavior. Indoor PM concentrations were consistently lower than outdoor levels, increasing from 7:00 AM, peaking between 9:00 AM and 12:00 PM, and decreasing during nap time (12:00 PM to 2:00 PM). CO2 levels were generally higher indoors than outdoors, peaking at 2:00 PM before decreasing. Windows were opened more frequently at 7:00 AM, 8:30 AM, and 3:00 PM. The correlation analysis revealed that significant factors influencing CO2 concentration were window opening duration. Ventilation rates per person at the daycare centers ranged from 1.77 to 10.69 m3/h, below both Korean and ASHRAE guidelines. The results of this study can provide valuable insights for developing strategies to improve indoor air quality in daycare centers that depend on window ventilation.