Using Low-cost Sensors to Assess the Impact of Outdoor Air Pollution on Indoor Air Quality of Buildings with Intake of 100% Ambient Air

DANIEL ALVARADO-VELEZ, Sabrina Westgate, Eben Cross, David Hagan, Nga Lee Ng, Georgia Institute of Technology

     Abstract Number: 390
     Working Group: Indoor Aerosols

Abstract
People spend most of their time in indoor environments, in which outdoor pollution is among one of multiple factors that determine indoor air quality (IAQ). Some factors that affect indoor pollution are ventilation rate, indoor sources of pollutants, indoor air chemistry, and building age, among others. Due to the expensive nature of continuously monitoring air quality using high grade research instruments, low-cost sensors are increasingly used in IAQ studies. In this study, we utilized paired QuantAQ MODULAIR and MODULAIR-PM sensors to measure the mass concentration of particulate matter (PM) of different sizes (PM1, PM2.5, PM10) and the mixing ratio of CO2, CO, NO, NO2, and O3 inside and outside two buildings on Georgia Tech campus. These two buildings are of different ages but both use 100% ambient air in ventilation. Measurements were conducted from Fall 2021 to Spring 2022. Results indicate that the indoor PM mass concentration generally follows a similar trend to the outdoor PM mass concentration, with R2 of 0.50 – 0.67, 0.49 – 0.62, and 0.34 – 0.60 for PM1, PM2.5, PM10, respectively. The contribution of outdoor PM concentration to indoor PM concentration varies by room. The highest observed contribution of outdoor PM1 concentration to indoor PM1 concentration was approximately 60%. Gas-phase pollutants did not show a good correlation between indoor and outdoor concentrations. This is thought to be because the gases studied are more affected by indoor sources and/or can react with other pollutant species. The indoor pollutants also show different trends depending on the day of the week, highlighting the contribution from specific sources. Results from this study provide insights into the extent to which IAQ is impacted by outdoor air and will help in determining improvements needed in building designs for better IAQ.