When the air outside is bad, is it still clean inside?

Like many metropolitan areas, Salt Lake City is no stranger to air quality issues caused by industrial and vehicle emissions. The city’s bowl-like topography can trap stagnant air causing inversions during the long winter months, not to mention the impact on air quality during wildfire season.

But what happens to the indoor air when the air quality outside is poor? Understanding that pollution poses multiple risks to human health and the environment, clean indoor air is an essential maintenance component of the University of Utah’s facilities infrastructure.

To better understand what happens to the indoor air when the air quality outside is poor, the U Facilities’ SEED2SOIL program awarded research grants for two projects to establish an on-campus baseline for indoor and outdoor air quality.

The study “Networked Indoor Air Quality Measurements at the University of Utah,” led by Dr. Kerry Kelly and Dr. Darrah Sleeth, is monitoring 20 buildings of varied ages and locations across campus. They have placed AirU sensors to collect data between August 2022 and January 2024 to measure temperatures, relative humidity, PM2.5 and CO2 concentrations. The data collected by sensors will monitor daily and seasonal fluctuations in indoor air quality, indicating whether poor outdoor air conditions affect indoor air quality under different heating, ventilation and air conditioning systems (HVAC) for each monitored building. A cloud-based, real-time data dashboard assists with quickly identifying concerns and evaluating changes made to a building’s HVAC system.

The project, “Quantifying the Impact of Outdoor Air Pollution on Indoor Air Quality at University of Utah Buildings,” led by Dr. Daniel Mendoza and Dr. Tabitha Benney, directly measures indoor air quality with research-grade (more sensitive) sensors. The project aims to understand the effects of Salt Lake City’s inversions, commuting, and other factors of outside air pollution that might affect indoor air quality. The team is analyzing pollution infiltration patterns between August 2022 and October 2023 to evaluate outdoor weather events such as inversions, peak commuting periods, and wildfires. Air is being monitored at the William Browning Building, Frederick Albert Sutton Building, and the Health Sciences Education Building using two instrument packages containing PM2.5, ozone, and black carbon sensors. For each selected site, one sensor package has been installed outside the study building and one inside the building.

With the final data, ventilation and filtration strategies for buildings across campus will be reviewed to improve the health of our occupants while maximizing energy efficiency. Potential strategies include smart technologies or automation tools that can trigger enhanced ventilation when thresholds are met, improvements for building winterization, tips for augmented building filtration during an outdoor air quality event, and increased venting before and after commuting hours for facilities located close to roadways to avoid bringing heavily polluted air inside. This research will provide an operational framework for air quality improvement campus-wide and within our broader urban community for years to come.