Magnetic Susceptibility of Tree Leaves as a Simple, Cost-Effective Means of Monitoring Air Quality

The high cost of air quality monitoring stations makes it difficult for citizens or local governments to monitor air quality in their own neighborhoods, especially in low-income communities. The objective of this study was to find a cheaper method of measuring long-term air quality, especially PM-2.5 (concentration of particulate matter smaller than 2.5 microns) and PM-10. The objective was addressed by measuring the magnetic susceptibilities of leaf samples of 12 species of trees collected within a two-mile radius of each of the seven air-quality monitoring stations in Salt Lake and Utah Counties, Utah, over a two-year period. After air-drying and crushing the samples, both low-frequency (0.46 kHz) and high-frequency (4.6 kHz) magnetic susceptibilities were measured with the Bartington MS3 Magnetic Susceptibility Meter. The best correlations between tree leaf magnetic susceptibilities and air-quality parameters were between the three-year average of PM-2.5 and the high-frequency magnetic susceptibility of leaves of pine (\textit{Pinus aristata}) (R$^{2} = $ 0.87, P \textless 0.01) and Norway maple (\textit{Acer platanoides}) (R$^{2} = $ 0.86, P \textless 0.01). The correlation with pine has been used to estimate PM-2.5 in two unmonitored locations heavily impacted by highway traffic (corner of 800 N and I-15 and corner of University Parkway and I-15, both in Orem, Utah). Further results will be reported at the meeting.