As Georgia Tech has resumed limited in-person instruction during the coronavirus pandemic, Professor Nga Lee “Sally” Ng has been monitoring the air quality of select classrooms on campus.


As Georgia Tech has resumed limited in-person instruction during the coronavirus pandemic, Professor Nga Lee “Sally” Ng of Georgia Tech’s School of Chemical and Biomolecular Engineering (ChBE) and School of Earth and Atmospheric Sciences (EAS) has been monitoring the air quality of select classrooms on campus.

To date, Ng’s lab has worked with the company QuantAQ to install 13 low-cost sensors in various classrooms across campus. These sensors are providing real-time air quality data that will help guide future measures to improve air quality.

The MODULAIR sensors monitor particulate matter (PM) of various sizes as well as other gas pollutants, including ozone, nitric oxide, nitrogen dioxide, carbon dioxide, and carbon monoxide, along with temperature and humidity and other meteorological parameters. Some of the sensors only monitor particulate matter (MODULAIR-PM). Ultimately, Ng’s team plans to install about 30 sensors around campus.

“Indoor air quality is an important topic, and a pandemic makes it even more so,” says Ng, whose research focuses on aerosol chemistry, air quality, and health effects.

Ng has teamed with Tech’s Facilities Management and Environmental Health and Safety (EHS) departments for this effort. Having real-time, cloud-connected air quality sensor networks provides Faculties and EHS with the tools to make proactive, data-driven decisions on improving indoor air quality.

Nazia Zakir, associate vice president of EHS, says, “While the classrooms are not occupied as they normally would be due to the social distancing protocols, we are seizing the moment to test the air quality in a variety of our buildings – both old and new – to see whether additional filtration measures would be beneficial.”

According to the Centers for Disease Control and Prevention (CDC), taking steps to ensure indoor ventilation systems are operating at peak performance as well as increasing the flow of outdoor air are key to maintaining a healthy and safe indoor environment.

Data from the classroom sensors is being analyzed by Ng, PhD students Sabrina Westgate (ChBE) and Taekyu Joo (EAS), and three ChBE undergraduate researchers in Ng’s lab (Abdulghafoor Tifoni, Kevin Jorgih, and Zahra Shivji).

“This project is moving at a superfast pace,” Ng says. The sensors were installed as soon as they were delivered and the students dedicated themselves to analyzing data immediately. “I’m really proud of these students for stepping up to contribute to this project and ensure a safe environment for everyone on campus.”

To date, the research team has found some air-quality correlations with classroom activity. “For example, we’ve seen an increase in the carbon dioxide level from breathing as well as aerosol levels when classes are in session,” Ng says

During the fall 2020 semester, many Georgia Tech courses are operating in a hybrid model (a combination of in-person and online instruction), with only a limited number of students permitted in class per session to ensure social distancing.

“When the number of students in classrooms eventually returns to normal again, the levels will of course be higher,” Ng says. “It will be interesting to see what the data will look like at those times.”

While she started this project because of the pandemic, she plans to leave the sensors in place over the long term. “One day the pandemic will be over, but continual measurements in classrooms will still be very valuable in improving indoor air quality. These real-time sensor networks provide data that can be linked to various indoor activities and outdoor pollution,” she says.

Prior to the start of the semester, Ng’s lab was also involved in a project to evaluate the effectiveness of several air purifiers in classroom buildings when no student traffic was present. The classrooms chosen for testing were mostly in buildings with multiple, heavy-use classrooms. The testing results allowed Facilities Management and EHS to identify which specific air purifier was the most efficient in decreasing particulate matter level.

Read a related article about GT campus efforts to improve air quality in classroom buildings on campus.