City Creek Nature Notes – Salt Lake City

February 26, 2017

February 26th

Filed under: Pollution — canopus56 @ 9:40 pm

Escaping Bad Air

8:00 p.m. Just a short half-mile jog today in a twilight canyon. The enveloping dark and solitude are welcome. They allow me to concentrate on the physicality of running, on form, and on sensation of rhythm.

The air is clear today, and the valley and canyon have passed the worst of the winter air pollution inversion days. On previous days I have noted escaping to the canyon and away from the inversion air pollution layer that covers the lower city (Jan. 5th, Jan. 8th, Feb. 1st, Feb. 15th). That there is less pollution at higher elevations is evident by the visual difference of the atmosphere between the city and the canyon beyond mile 1.0, but scientific studies also support my impression.

In 2010, Silcox at the University of Utah and colleagues installed a series of air quality monitors along a transect line from the William Browning Building at the University of Utah to a ridgeline between City Creek Canyon and the Avenues. The highest monitor was at highest point of the ridgeline visible to the southwest from milepost 1.5 in the canyon. Silcox et al monitored PM2.5 particulate matter during January and February inversions, and they found during the heaviest inversion pollution events there was about a 50 percent reduction in PM2.5 levels between the elevation of the Salt Lake City Airport near 4265 feet above sea level (1300 meters) and the highest station on the ridgeline near 5900 feet in elevation (1800 meters). Since 2010, other vertical pollution gradient monitoring efforts began. The first by the John Sohl’s HARBOR group from Weber State University involves releasing weather balloons to an altitude of 500 feet above the surface at the Salt Lake City International Airport (Mountain Meteorology Group, 2017a) and the second by Lareau and colleagues at the University of Utah involves laser measurement of the density of the air (Lareau et al; Mountain Meteorology Group, 2017b). In January and February, 2017, the Division is undertaking a vertical pollution study using and airplane to fly through the inversion layer to collect physical samples (Utah DEQ, 2017). On a daily, real-time basis, the most useable source for a vertical air PM2.5 concentration is a network of less accurate citizen-science air monitoring stations, Purple Air. That network typically shows a gradient of reduced PM2.5 pollution from the valley to stations on the high Ensign Peak and Avenues benches and for one station in Emigration Canyon (Purple Air) (Personal observation).

All of these sources indicate that by jogging in the canyon, I am reducing my breathe intake of particulate matter pollution as compared to the valley, but perhaps by not so much as I estimate subjectively by just looking at the air.


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