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.
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.