Greg Bunce: Welcome to another episode of the Utah Geospatial Podcast. This is Greg Bunce.
Matt Peters: And I’m Matt Peters.
Greg Bunce: And we’re from the Utah Geospatial Resource Center. This podcast will be bringing you Geospatial news from across Utah.
Today on the show we chat with Lexie Wilson from the Utah Division of Air Quality. Lexie explains the differences between summer and winter air pollution here in Utah, the latter being the inversion which we all know so well, but she explains the science behind it.
She also talks about the current monitoring system, which consists of regulatory monitors, but also non-regulatory ones, which are the ones that you can put in your own backyard. Then we dive into the modeling work that they do, specifically the photochemical modeling. This is where they take emissions data, meteorology data, and terrain data, and then try to recreate an episode or an event that has happened in the past and then apply that to the future.
This is where UGRC comes in, where we provided them the land use data for the model to work. And the result is that the division can then make policy and permitting decisions based on this data. So let’s listen in.
Matt Peters: Today on the podcast we have Lexie Wilson. Lexie is with the Department of Environmental Quality, specifically Air Quality. And, you know, we’ve had a lot of discussions here at UGRC with the DEQ, but I have not had the opportunity to really meet you. So I’m really looking forward to this. So maybe you could give us a little bit of your background and what you do for DEQ.
Lexie Wilson: Yeah, definitely. So I’m an environmental scientist here at the Division of Air Quality, within the Department of Environmental Quality. My background is actually in meteorology. I got my bachelor’s degree at the University of Utah in atmospheric science. And that’s what we do here. My group specifically works on air quality modeling.
Greg Bunce: So Lexie, when we think of air quality in Utah, I think most of us immediately think of the inversion in the winter. But there’s also summer ozone, right? Can you explain the difference between the two?
Lexie Wilson: Yeah, so we have two main seasons of air pollution here in Utah. In the wintertime, we have our inversions, which trap pollutants in the valley. And the main pollutant of concern during the winter is PM2.5, or particulate matter that’s 2.5 microns or smaller in diameter. And that comes from combustion sources like cars and heating our homes, but it also forms chemically in the atmosphere.
In the summertime, our main pollutant of concern is ozone. And ozone forms when we have pollutants like nitrogen oxides and volatile organic compounds reacting in the presence of sunlight. So it’s a very different chemical process, but both of them are influenced heavily by meteorology and topography here in Utah.
Greg Bunce: And so how do you monitor all of this? I know there’s monitors all over the valley.
Lexie Wilson: We have a network of regulatory monitors throughout the state. These are high-quality instruments that are maintained and calibrated regularly. And the data from these monitors is used to determine if we are meeting the National Ambient Air Quality Standards, or NAAQS, set by the EPA.
But we also have a growing network of non-regulatory sensors. These are lower-cost sensors that are becoming more popular with the public. You might have seen PurpleAir sensors, for example. These sensors can provide more spatial coverage, but the data quality isn’t as high as our regulatory monitors. So we have to be careful how we use that data.
Matt Peters: So you mentioned modeling earlier. Can you tell us a little bit more about that? What kind of modeling do you do?
Lexie Wilson: We use a type of modeling called photochemical modeling. This is a complex computer model that simulates the chemical and physical processes in the atmosphere. It takes inputs like emissions data, meteorological data, and terrain data, and it calculates the concentrations of pollutants over a specific area and time period.
We use this model to understand how different sources contribute to air pollution and to evaluate the effectiveness of different control strategies. For example, we can use the model to see what would happen if we reduced emissions from cars or from industrial sources.
Greg Bunce: And where does UGRC fit into this?
Lexie Wilson: UGRC provides us with some of the critical data that we need for our modeling. Specifically, we use land use data from UGRC to characterize the surface of the earth in our model. The model needs to know where there are urban areas, where there are forests, where there are agricultural lands, because these different land use types affect how pollutants are emitted and how they disperse in the atmosphere.
So having accurate and up-to-date land use data is really important for our modeling efforts. And we really appreciate the work that UGRC does to provide that data.
Matt Peters: That’s great to hear. It’s always good to know that our data is being used for something important like air quality.
Lexie Wilson: It definitely is. Our modeling results are used to inform policy decisions and permitting decisions. So the accuracy of our data directly impacts the decisions that are made to protect public health and the environment.
Greg Bunce: Is there anything else you’d like to share with our listeners about air quality in Utah?
Lexie Wilson: I would just say that air quality is a complex issue, but it’s something that affects all of us. And there are things that we can all do to help improve air quality, like driving less, trip chaining, making sure our homes are energy efficient. Every little bit helps.
And if people are interested in learning more, they can visit our website at air.utah.gov. We have a lot of information there about current air quality conditions, our monitoring network, and what people can do to help.
Matt Peters: Excellent. Well, thanks for joining us today, Lexie. It’s been a pleasure talking with you.
Lexie Wilson: Thanks for having me.
Greg Bunce: Yeah, thanks Lexie. And thanks to our listeners for tuning in. We’ll catch you on the next episode.