Engineering students monitoring air quality on campus

Particulate matter in the air may not be visible, but its effect on health can be very real. Carnegie Mellon’s campus is no exception. That’s the current focus of a junior-level class in Civil and Environmental Engineering (CEE), where a group of students is currently studying air quality levels around campus. Their main goal is to better understand air particulates and determine what can be done to avoid the worst of their impact.

The course “Experimental & Sensing Systems Design” aims to teach students how to use a system of sensors to take and analyze measurements that may be useful in their field of engineering. It’s co-taught by Fethiye Ozis and Sarah Christian, professors in the CEE department. Ozis, who focuses on sustainability and environmental research, developed this semester’s project with the city of Pittsburgh in mind.

“Pittsburgh is known for its air quality issues,” Ozis said in an interview with The Tartan. She follows air quality issues with her students in CEE and is passionate about it, having done her Ph.D. research in the subject. It stood out as the ideal topic to choose for her sensing class, all the more relevant now after recent toxic events like the train derailment in East Palestine, revealing unseen pollution sources and the cracks in today’s aging infrastructure.

The class worked with Carnegie Mellon’s facilities department to develop the project and acquire the necessary sensing equipment, talking with facilities management and the University Engineer Steven Guenther. Facilities management invested in 15 sensors that the students could deploy. Capable of sensing particulates in the air at a width of 2.5 micrometers, matter known as PM 2.5, the sensors by PurpleAir are low-cost and provide publicly available data the students can access and investigate.

The teams set out with particular research questions they wanted to answer as a result of their data collection — when is the safest time to exercise outdoors? Are there patterns for when air quality peaks and falls? Are there any locations of concern on campus? How does campus air quality compare to the Pittsburgh region? Lastly, the teams contemplated the best ways to inform community members about their findings, the local air quality situation, and any associated risks.

The project teaches students how to run an environmental sensing system, but it also aims to inform the campus community, which the students and faculty are particularly excited about. It gives the students a chance to get involved with the school, working on a scale large enough to make a real impact on the university community. They’ve done work from setting up the sensors to making final evaluations, with the ultimate goal of helping people avoid harmful air particles when possible.

One basic finding is that air quality can fluctuate day-to-day and even hour-to-hour, Ozis explained. People on campus with preexisting lung conditions, such as asthma, may be more sensitive to those changes. Knowing when high-Air Quality Index (AQI) times occur can be very informative. Respiratory aggravations can potentially be avoided by limiting outdoor activity during certain hours or days, at which point “indoor air quality is better than outdoor air quality,” Ozis said.

A main learning objective for the course is for the students to set up the experiment, collecting and analyzing the data themselves. To better understand what the sensors are and what they’re capable of, the class was assigned to read the work of Carnegie Mellon’s Center for Atmospheric Particle Studies, to get an understanding of how the sensors work, the theory behind them and how they can be used to answer the group’s research questions. The Center conducted air quality analysis at the East Palestine derailment site earlier this year.

The sensors used in the students’ project were first calibrated in the CEE basement laboratory and adjusted to Pittsburgh’s specific air standards. Each device was tested in-house for two days to make sure it was of good enough quality, giving accurate enough measurements to be deployed. The campus and surrounding area were divided into five sections, with each team assigned a certain area to research. Over two days, the sensors were placed in carefully selected locations based on wind direction and ambient pollution sources which may be impacting the community.

Each team had three sensors to place, with the only constraint being the need to connect to a power source. Students attempted to cover the area as well as possible, placing sensors based on where air pollution might be stemming from. They considered Bellefield Boiler Plant, a power station nearby to campus, as one point source, as well as busy roadways such as Forbes and Fifth avenues as possible line sources of pollution. Being able to deploy a large number of sensors allows for “a good map of what's really happening,” Ozis said.

The sensors have been collecting data since February 22, taking a sample of air quality every 10 minutes and posting the publicly available results live on the PurpleAir website. After collecting the data, the class will spend time making sense of it all, aiming to answer the research questions they set out with. Each team will present their findings in a final presentation as the project’s conclusion, with the goal of eventually sharing that knowledge with the school to improve campus wellbeing.