The Causes of Air Pollution in the Salt Lake Valley

In September of 2014, I received a call from Brad Stone who works in the Office of Information Technology at Brigham Young University to see if I’d like to be part of a team of Big Data researchers from various organizations in the Salt Lake City, UT area.  Brad was a student in one of my classes.  His team, WINversion, was part of a competition that was organized by Utah Geek Events and local user groups to utilize big data to provide insights into air quality problems in the Salt Lake City Valley.  

Brad wanted to utilize Sologic root cause analysis to help his team understand the causes of air pollution in the Salt Lake Valley, specifically during inversions that occur in the winter months.  His hope was that bringing everything together in a cause and effect chart would provide his team with insights into how to go about identifying statistical correlations through big data analysis.  This sounded super interesting to me and I agreed immediately.   In the interest of full disclosure, Sologic is listed as a sponsor of Brad’s team because we donated my time and expenses to complete the RCA.

The RCA itself did not disappoint.  Brad arranged to have Dr. David Whiteman, professor at the University of Utah, join us.  Dr. Whiteman is an expert in pollution in the Salt Lake Valley.  Dr. Whiteman is one of the authors of a 2011 paper published in the Elsevier Journal that examines wintertime PM 2.5 concentrations during persistent, multi-day cold-air pools in a mountain valley.  Read the paper here.

PM stands for “Particulate Matter” and “2.5” is the diameter of the particle, in microns.  This is a pretty small particle and, when it comes to pollutants, size really does matter.  Because these particles are so small, they can bypass many of the body’s natural filtration systems.  The health hazard is significant.  A 2010 study by the State of Utah found that the odds of asthma-related emergency department visits in Salt Lake County rise by 42% during days 5 – 7 of prolonged inversion periods.

Particulate Matter in Air Quality RCA

This cause and effect chart was built from a top-down perspective.  This means that we looked at the macro-level causes for PM 2.5 instead of the individual causes of individual events.  I thought this was the best approach because it would allow us to achieve our goals within the time allowed (1 day) and keep the chart to a single page.  View the cause and effect chart. 

We learned that PM 2.5 particles are often the chemical precursors to more dangerous substances.  Many of these precursors come from emissions (mostly vehicle tailpipes and industry).  Over time, they react with other chemicals to form substances that are more dangerous to susceptible residents (like those that suffer from asthma).  Think of the Salt Lake Valley as a big bowl.  In the bottom of the bowl, there are multiple sources of PM 2.5.  Normally, winds circulate throughout the valley.  This blows the chemicals out of the bowl and brings fresh air in.  But in wintertime, the conditions are such that a persistent cold air pool forms in the valley.  This occurs when cool mountain air (which is denser) spills over the mountains and settles to the valley floor.  It is then trapped by warmer high-pressure air on the top.  This effectively puts a lid on the bowl, preventing circulation (picture living in a fish tank that never gets cleaned).  After several days, the exposure to PM 2.5 particles begins to have significant negative health effects, particularly on those with the greatest sensitivity.  

One of the most interesting conclusions of the Big Data group was that there is little correlation with driving and levels of PM 2.5 during an inversion.  In other words, telling people to stop driving their cars during a persistent cold air pool will have little immediate impact on the health of valley residents.  That’s because by that point, the damage has already been done.  Vehicle emissions are the precursors to the more dangerous forms of PM 2.5, and they need time to react.  The better long-term solution is to reduce the overall reservoir of chemical precursors before such an event occurs.  It’s not like a burn-ban, which immediately reduces larger atmospheric particles.  PM 2.5 is a problem that apparently does not have a reactive solution.  Reducing these levels will take a more proactive, long-term commitment by valley residents to reduce the amount of chemical precursor emissions before they become trapped in the valley.

While all teams in the competition did a fantastic job, I’m happy to report that our team, WINversion, was selected as the winner!  Congratulations to Brad and the team!

We teach in class that the Sologic RCA methodology is a universal and scalable problem solving method.  Taking on projects like this really prove the point – and they help those of us at Sologic stretch our knowledge, skills, and Causelink software by exploring beyond our traditional comfort zones.  If this inspires you to apply Sologic to something out of the box, get in touch and we will be happy to support you in the same way.

Learn more about Sologic RCA