(574e) Characterizing PM2.5 in a Mountain Valley: A Community Engagement Project

Authors: 
Silcox, G. D., University of Utah
Kelly, K., University of Utah



The University of Utah, Lowell Bennion Service Center encourages instructors to collaborate with community partners in their courses. Such courses appear on a student’s transcript and are given a Community Engaged Learning designation. Chemical Engineering 5305/6305, Air Pollution Control Engineering, has collaborated with the Utah Division of Air Quality on two such projects related to PM2.5 in the Salt Lake Valley.

In the first project, PM2.5 concentrations were measured in residential and nonresidential areas of Salt Lake City, Utah during persistent, stable, wintertime conditions. Concentrations generally decreased with increasing elevation; decreases of up to 30 percent were measured as elevation increased from 1300 to 1600 m. During a particular 8-day episode, concentrations of PM2.5 increased linearly with time by about 6 micrograms per cubic meter per day. During the mix-out of stable conditions, higher elevation sites were sometimes exposed to clean air as much as 24 hours before lower elevation sites.

In the second project, positive matrix factorization (PMF) was used to identify sources of PM2.5 in the Salt Lake Valley. The main contributor is secondary ammonium nitrate. The analysis also showed that ammonium chloride is an important source of secondary aerosol (10 – 15 % of total PM2.5) during stable wintertime conditions. Comparison of the source attribution results to county-level emissions inventories show generally good agreement except for wood smoke and dust which contribute more to PM2.5 than suggested by the inventories.

Some of the students are genuinely interested in the projects and enjoy working with and collecting data. Comments from the course evaluations include, “PM 2.5 project was an effective learning experience”, “the group project let me get hands-on experience with a testing device and forced me to work in a group”, and “another great aspect of the course was using the EPA PMF program because it was interesting to study real data and find potential sources of different emissions”.

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