City Creek Nature Notes – Salt Lake City

February 27, 2017

February 27th

Filed under: Pollution, Weather — canopus56 @ 9:15 pm

Thin Air

5:00 p.m. Another day of snow whitens the canyon.

Jogging in the canyon is an antidote to depression. It infuses oxygen into and restores the brain, calms the body, and returns perspective. For some time based on popular science reporting, I had thought that the lower atmospheric pressure contributed to mild hypoxia that might induce feeling blue. Atmosphere decreases in density as elevation increases. A standard barometric equation indicates that Salt Lake City and the canyon should have 86% of the standard atmospheric pressure at sea level, or about 26 inches of mercury as opposed to 29.92 inches of mercury at sea level, and this is consistent with reported weather data (NOAA).

After leaving the canyon today, I look for the articles underlying the mild hypoxia hypothesis. In 2011, Kim at the University of Utah and colleagues statistically associated increasing altitude with the risk of suicide by examining suicides in 20 counties at altitudes between sea level and 11,500 feet (Kim). Salt Lake City is at approximately 4,300 feet in elevation. Relying on that the coefficient of correlation between altitude and suicide was positive, they concluded that less air was a significant risk factor for suicide. However, the coefficient of correlation was only 0.51, little better than chance; but, the standards of proving epidemiological causation is not the same as in mathematics. In 2015, Kaneka at the University of Utah and colleagues in a controlled experiment demonstrated a physical causal connection between low air pressure and depression by raising rats in hypobaric chambers (Kaneka). But, depression was only seen in female and not male rats, and this indicates the need for more research.

Air pollution, including particulate matter, is also believed to cause depression. In 2015, Bakian at colleagues at the University of Utah compared Salt Lake Valley suicide data for 2000-2011, stratified by polluted and non-polluted season (Bakian). They found that the relative risk of suicide two days after heavy spring inversions of PM2.5 was 1.20 as compared to other seasons. The relative risk of suicide three days after spring and fall inversions with high levels of gaseous nitrogen dioxide (NO2) was 1.35. Although not measuring mood, in 2012, Beard and colleagues at the University of Utah found that winter time inversions with high PM2.5 levels were associated with higher levels of emergency room visits for asthma (Beard).

By jogging in the canyon, my breathing takes in more harmful pollutants, but at a reduced level than I would receive by jogging in the valley. But the adverse effects of those pollutants are offset by the health benefits of taking in more oxygen.

In Thoreau’s “Journal” on February 27th, 1853, he notes how easily squirrels can open cones, while people cannot. He opens a pine cone by storing it in a drawer.

On February 27th, 1894, an employee of the Waterworks Department reported seeing a mountain lion in City Creek Canyon. City Councilperson Newell noted other mountain lions had been seen, and he suggested that the City authorize a hunting party to go into the canyon and “kill off the man eaters” (Deseret Evening News).

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