Play Live Radio
Next Up:
Available On Air Stations

What does it really mean when Utah DEQ talks about air quality?

Winter inversion, obscured downtown Salt Lake City, seen from U of U campus, Dec. 19, 2022
Elaine Clark
Looking northwest across the campus of The University of Utah toward a hazily obscured downtown Salt Lake City, Dec. 19, 2022.

Inversion season is upon us and with it, some bad air days. But when should you forgo your daily run and when should you stay inside altogether?

Utah’s Department of Environmental Quality gauges the air daily with a color-coded ranking ranging from good (green), to hazardous (dark burgundy). But those rankings leave many scratching their heads. Bryce Bird, the director of Utah’s Division of Air Quality, said that beyond the ratings, self-assessment is part of the equation.

“If you feel burning in your eyes and the back of your throat, if exercising causes tightness in your chest, that's certainly an indication for you that that level of air pollution is unhealthy for you,” he said.  

Then there’s the question about the term “haze” used by the National Weather Service. Is that haze pollution-laden, or is it weather-born haze or maybe a bit of both? For Bird, “visual impairment as one thing to look at, but really focusing on the data that's available from air monitors that help us to understand what the concentrations are or what pollution is leading to that haze.”

As Utah continues to go gangbusters with growth, the rising number of people (and their cars) will start to cramp efforts to clean up the air in hotspots like the Salt Lake Valley. While many see growth as primarily a challenge for housing, or water — Bird sees it as the biggest challenge for air quality.

The plans that we've put into place have always anticipated growth and tried to predict the impacts from that,” he said. “But of course we're growing at such a fast rate, the air pollution models are catching up, and it's very challenging.”

This interview has been edited for length and clarity.

Pamela McCall: Let’s talk about the color-coded air quality index and what each level means. Green is good and self-explanatory. What’s it look like on a yellow (moderate) day?

Bryce Bird: Really in the simplest terms, when we're at the moderate level, we are at a level that is expected not to have a health impact. 

PM: So I can go from my morning run.

BB: Yes.

PM: And orange (unhealthy for sensitive groups). Who are considered part of a sensitive group?

BB:  Those that are either children — because they breathe more quickly, bring more of the particles into the air — or the elderly, because they've lived a lifetime of impacts from a number of air pollution sources or other impacts on their health, the heart disease and other things, or those that have a compromised respiratory system. And so if somebody has asthma, somebody has emphysema, there's heart disease involved that would be that sensitive group.

PM:  How bad does the air have to get to be red (unhealthy for everyone)? 

BB: The concentrations are different for each pollutant. But when we're at 150% of the air pollution standard that EPA has set, that's when we go into that unhealthy for everyone on the color scale. That's the red air quality.

PM:  Hazardous. Which is dark burgandy and the worst ranking. What would bring that on?

BB: So really, it's only been as a response to wildfires. And so if there's a local, large wildfire, sometimes we exceed that level. Even as bad as some of the wildfire exposures have been from distant wildfires, we're usually not quite into that hazardous area.

PM: The National Weather Service sometimes uses the term haze in its Salt Lake forecast, and that's a term some are frustrated by. They say, ‘call it air pollution.’ How do we know if haze is from a weather event or it's actual air pollution? 

BB:  When I think of haze, I'm thinking about particles in the air — whether they are natural, like fog is a good one, or something that comes from an air pollutant source — that impacts our ability to see long distances and a clear view of the mountains here in the valley.

PM: In using that term haze, we're not breaking it down for people. Rather than leave it open to interpretation should we break that down and say what the haze is based on? 

BB: The way I would address this is using the visual impairment as one thing to look at, but really focusing on the data that's available from air monitors that help us to understand what the concentrations are or what pollution is leading to that haze. Your eyes are one indication of air pollution, but really, we sometimes do need to rely on the air monitors to understand what the actual concentrations are. In fact, most of the visible impairment that we see even during inversion periods is because of the water vapor that's condensing in the atmosphere. That fog formation is actually the biggest thing.

PM: Grant money from the EPA to enhance air quality monitoring in Utah was recently announced. What will enhanced monitoring tell us that we don't already know?

BB:  What this additional funding is, is to look at neighborhood exposures. So it's putting more monitors out in those areas of highest expected air pollution concentrations. And then also part of the funding is then to provide that information on our website as a resource for people so they can understand on a daily basis, on an hourly basis, what their potential exposure is so that they can make choices to protect themselves.

Pamela is KUER's All Things Considered Host.
KUER is listener-supported public radio. Support this work by making a donation today.