Exploring the gospel principles of earth stewardship

Air Pollution Case Study: Utah’s Wasatch Front

They say you should never start a speech (or a blog post?) with an apology, but I’m breaking that rule today.  I knew when I began the air quality series that I wanted to write a post about air quality concerns in the communities along Utah’s Wasatch Front—LDS Earth Stewardship has many members and blog readers in Utah, after all.  But I haven’t spent any real time in Utah since graduating from college a dozen or so years ago, and nearly all of my professional and academic experience in air quality has been in California.  So I begin with an apology–that I can’t give as much perspective to Utah clean air issues as I’d like—and a request:  Please, if there’s something you’d like to know about that I haven’t covered in the post, leave your questions in the comment box below.  I’ll do my best to research and respond.


Fine Particles

Utah’s major air quality problem is the presence of tiny particles of solids and liquids suspended in the air, called particulate matter, or PM.  “Fine” particles are considered those with diameters less than 2.5µm (read “micrometers,” or “microns” and equal to one billionth of a meter), and are often referred to as PM2.5.  For size comparison, the finest beach sand is usually about 90µm, so PM2.5 are very, very tiny.  This is problematic because it means that they are small enough to be inhaled deep into the lungs.  Dust particles that are slightly larger—say, 10µm in diameter—will be trapped by the hairs and mucus in your respiratory tract and sneezed or coughed up.  That can be unpleasant—think about the last time you cleaned out a dusty corner of a garage or shed—but the more insidious health effects come from the fine particles that make it to the deepest recesses of the lungs.  These contribute to pulmonary diseases like asthma and emphysema.  Even more troubling, recent research suggests that fine particles are crossing into the bloodstream, where they irritate blood vessels and can contribute to cardiovascular disease.

Most fine particles are generated as a by-product of burning something.  Smoke from fireplaces or wildfires, certainly, but more significantly in urban areas, particles come from the burning that happens in internal combustion engines, like the ones in most cars and trucks.  These processes emit particles directly and also emit gases that can then form more particles in the atmosphere.



The problem in Utah isn’t just that fires and internal combustion engines are putting particles and particle-forming gases into the air.  This is true in many places.  But Utah’s soaring mountains create valleys where cold air pools.  The normal state of atmospheric affairs is for air temperature to decrease with higher elevation (hikers are familiar with this).  The warmer air at the surface then has a tendency to move upward (the familiar adage “heat rises”), dispersing with it the pollutants emitted close to the ground.  But in Utah’s valleys, particularly in the wintertime, weather systems can switch the normal order of things, creating temperature inversions that trap cold air close to the ground.  With no vertical movement to disperse the pollutants, they stay trapped near the ground, and particulate matter concentrations can soar to unhealthy levels.  At the moment, Utah puts certain precautions into place during winter inversions—such as bans on home fireplace use—to try to keep PM2.5 concentrations in check.  While this is prudent, in my opinion, it’s little more than an emergency measure.  Such measures are best, in my view, coupled with longer-term measures to reduce the year-round baseline levels of pollutants emitted into Utah’s skies.



Although it would be nice to be able to point the finger at some select set of industrial sources for creating Utah’s air quality problem, it’s just not accurate.  To be sure, industrial sources do contribute to Utah’s air pollution, and these sources should be held accountable for keeping their emissions as clean as possible, but recent emission inventories conducted as part of Utah’s federal clean air plans point to mobile sources —cars and trucks, but also off-road construction equipment and tractors—as the source of the bulk of the fine particle pollution in Utah’s urban areas.  As I pointed out in my case study on Los Angeles air quality, the source of the problem is us—every person who motors around Utah’s roadways.  I don’t mean to lay blame here.  As I said, I don’t know Utah well, but I don’t imagine the average resident spends his or her days thinking of ways to recklessly pollute the air.  But what I’ve observed in places I do know is that most people tend to get around in ways that are convenient for them, without thinking too much about the environmental impact of their transportation.  To the extent that the number of cars on the road can be reduced—think better public transit, more bike lanes—and the cars on the road can be made to run cleaner, Utah will be able to make improvements in its air quality.

In a way, one might see this as somewhat liberating: if you live in Utah and want to improve air quality, you don’t have to wait for large factories to clean up.  You can—and I know many of you do—explore how biking, walking and public transit can be part of your transportation toolkit.  Of course, there is a role for governments here, too—requiring cleaner engines in cars and trucks, and making transit and biking more available and practical for more people, but as members of a faith that prizes individual agency, knowing that your own actions can help improve local environmental problems can be empowering.



I’d love to hear questions and comments, especially from those of you who do know Utah well.  I promise to research and follow-up.


  • JP

    Thanks, Laura! This helps me understand why it’s always the coldest, most miserable days that are also the dirtiest.

    One of the things that many of us Utahns are also talking about is living closer to work. That’s one of the main ways in which alternative transportation becomes more plausible. Personally, I hate waiting for the bus. It frustrates me to not feel in control. So I bought a house close to work so I could walk or bike. I would love to see some of the major employers create incentives to live closer–or at least put in bike lanes/bus stops when they redesign their campuses (ahem, BYU).

    Living close to work has lots of other benefits for families and communities too. I know I’ve become a convert.

    • Laura

      I agree! In addition to making alternative
      transportation more viable, it shortens the total miles on the road for people
      who do choose to drive. And you get savings in both time and money on
      your commute, so it’s really a win-win. There’s
      a movement in urban planning now towards “smart growth”—creating cities that
      are denser, looking at opportunities for additional housing within existing
      city limits instead of sprawling outward.
      There are a lot of challenges, but it provides a way for individual
      cities to get in on the sustainability action.
      I wonder how that’s playing out in Provo? I think that’s one city with a lot of
      potential for really great neighborhoods and communities. Personally, I think the benefits you cite for
      building community and just personal happiness are more important than the air
      quality benefits from living close to work, but those don’t hurt, either.

  • Taylor

    Since I live here, I’ve been thinking about this a lot, especially this last winter when things got usually bad. I’m proud to say that I’ve been using a combination of biking/walking/and public transit to get to and from work for a year and a half now, but it can be hard at times.

    One of the issues exactly what you pointed out- the inversions are at their worst in the winter. Many people see it as one thing to ride your bike or wait for a bus on a pleasant spring morning and as something completely different to do it on a frigid and dark winter morning.

    Of course the personal advantages of exercise, a cleaner environmental conscious, a much less stressful commute (especially during a snow storm), a fatter wallet from not having an extra car payment, and knowing that ice and snow are much nicer to bike tiers than thorns and mud help offset the problems for me. But not everybody is willing to make the attempt during the winter.

    Personally I favor some sort of deep discount on public transit during the times of year when the inversion is an issue. But I have heard some rumblings about making the I-15 corridor a toll road with variable rates for times during the inversions, which would be very interesting to see.

    • Laura

      Congratulations on a successful
      transition to bike commuting! The problems you cite are exactly why I
      think the episodic controls during inversions should be, at best, a temporary stopgap. Air pollution episodes are often the worst time to
      be out on a bike—there are the weather concerns you mention (and in places with summertime ozone problems, you’re more likely to see very high ozone on the hottest days, so it cuts both ways), and then even for people with mild asthma or other respiratory problems, additional pollutants can be very irritating. I believe the real solution is to bring down the baseline levels of pollution, so that when inversions come, there’s less pollution to get trapped near the surface.
      That’s a lot harder, especially politically, than just telling people not to use their fireplaces a few times a year, but I think it’s a more lasting solution.

      Your transit idea is a great one, and has some precedent. I know in Sacramento where I live, some of the local transit companies have offered free bus fare on our “Spare the Air” days. They haven’t
      been able to do it every year because of funding, but it’s a start. Maybe UTA could think about something similar? It seems to me it’s also a great way to get people to try transit who might not otherwise do so.

  • davedd233

    Great stuff, Laura. To what degree do we need to worry about electric trains being powered by electricity from coal?

    • Laura

      That is such a great question. I have to admit, I usually think of
      coal-fired power plants being mostly back East, but I was wrong on this. It looks like there are several coal-fired
      power plants in Utah: http://www.sierraclub.org/coal/map/. And it looks like Rocky Mountain Power (is
      that the main electricity provider along the Wasatch Front?… I relied on google
      search results, but I’m not familiar enough with the area to know) gets a
      pretty significant chunk of their electricity from coal: http://www.rockymountainpower.net/content/dam/pacificorp/doc/CCCom_Update/2013/April_13/RMP_UT_ConservationReport_F_no_crops.pdf
      (look at the pie charts on the last page of that document). So yes, assuming that the electric train /
      light rail uses this same municipal electricity supply (I would imagine they
      do? but this is not my area of
      expertise), then it’s powered in part by coal.
      Yikes! I had no idea!

      • Dlynnsor

        On coal: Actually BYU has a coal burning (what? power plant? dunno exactly). Anyway I know they have it. They do not use it in the winter because of its contribution to the inversion problems. They use it in the summer. You can see where the coal is delivered in the middle of the parking lot southeast of the Crabtree Building. You can also see the nearby smokestack(s) in that area. Bill Rudy, can you tell us more about this?

        • Dlynnsor

          Whoops, southWEST of the Crabtee (NOT southeast). Sorry.

    • Laura

      Davedd233–You’ve got me curious about this, now. I just sent an e-mail to UTA to ask which utility provider they use. I’ll update this when I get more information.