The state is still trying to bridge the gap in its monitoring network, a state environmental scientist said.
In late January, a weather satellite captured a stream of dust lifting off the Great Salt Lake near Farmington Bay and drifting southeast toward Salt Lake City.
The satellite imagery shows a “great example” of how narrow those plumes can be, said Rachel Edie, an environmental scientist with the Utah Department of Environmental Quality.
“It kind of looks like a piece of spaghetti,” Edie said, adding that sensors not directly downwind won’t sense or measure the skinny bands of dust.
It also illustrates how tricky it can be for the state to measure dust pollution from the plumes using its existing network.
Two sensors near the airport measured elevated levels of PM10, or particulate matter like dust measuring less than 10 microns in diameter. But the average measurement at those sensors showed roughly 90 microns per cubic meter that day, which was still below the health standards of 150 recommended by the U.S. Environmental Protection Agency. Readings during the storm could have been much higher.
The state’s monitoring network hasn’t historically captured the emerging issue of the dust coming off the drying lake bed, Edie said. That’s a growing health concern because of toxins in the sediment.
“We know we have big dust storms and big dust sources that have existed for a really long time,” she said, but the state is trying to bridge the gap to better measure what’s coming off the lake.
Kevin Perry, a professor at the University of Utah, has studied the effects of Great Salt Lake dust for years, though the lack of available monitoring has made that difficult.
“The simple fact of the matter is, five years from now, I want to be able to answer the basic questions of how often the dust comes off the lake, what the concentrations are and whether or not it poses an actual health hazard, because I don’t know the answers right now,” he said.
“Nobody does,” he added, “because we don’t have the data.”
The state is working to build up its monitoring capacity, Edie said – but that will take time.
‘Exceedingly difficult’ to add monitoring sites
Because the Great Salt Lake is large but shallow, a decline of even a few feet can expose vast stretches of lakebed. That exposed lakebed – which includes toxins like mercury and arsenic from past mining activities – could create a public health disaster due to blowing dust and the lake’s proximity to major Wasatch Front cities like Salt Lake City, Layton and Ogden.
During the 2023 legislative session, the lake was only a few months out from its record low, prompting a flurry of actions intended to save it, including funding for additional instruments to measure dust.
After Edie met with “pretty much any local researcher” with expertise in dust coming off the lake, the state added instruments at four monitoring sites specific to Great Salt Lake dust, including sites in Brigham City and West Valley City – a west-side community that at least one study found is particularly affected by dust blowing off the drying lake bed.
Utah is still looking to put in a monitoring site to pick up dust blowing northeast off Farmington Bay, Edie said, and has been trying to find somewhere to secure or lease land and drop in power for two years.
The state might try to revive a site at the beginning of the causeway to Antelope Island, she said, but it’s not in an ideal spot because it’s too close to the lakeshore and not in the affected neighborhoods.
Between tens of thousands to buy instruments, $55,000 for a secure shelter, anywhere between $15,000 to $120,000 to run power to a site and other costs like consumables and staff time, it’s “exceedingly difficult” to set up a brand new station, Edie said.
Once sites are set up, she said, the monitors generally only run for about five years because dust is “really tricky” to measure since the equipment struggles to function if it picks up a lot of dust or if there are pressure changes.
“If it were just the instrumentation and we could plug it into an outlet anywhere, I think it would be a lot easier to do this,” she said – but the state can’t just drop monitors into a field without security and power.
Beyond Farmington Bay, the state is still looking to add more monitors, Edie said.
DEQ staff have developed a proposal and will start getting feedback from academic researchers, local officials and others with expertise on the lake and the effects of the dust in June, she said, then see if there’s a way to accommodate suggestions without the bounds of the department’s budget.
Utah’s current network has limitations
Water levels at the Great Salt Lake could lower as much as one-and-a-half feet this year, said Perry from the University of Utah, which doesn’t bode well for future dust events.
The state “recognizes the need for enhanced dust monitoring and is working diligently to leverage the money provided for a dust monitoring network to achieve their goal of being able to characterize the dust in northern Utah and beyond,” Perry said.
One such shortfall is Air Quality Index, or AQI, readings that don’t tell the whole story.
The Utah Division of Air Quality reports AQI by county on its website with hourly updates. But, Perry said, Utah’s AQI only factors in ozone pollution and PM2.5, which are particles that are 2.5 micrometers or smaller in diameter.
But Great Salt Lake dust is mostly larger PM10 particles, which Perry said the AQI doesn’t include because of Utah’s lack of monitoring.
“I’ve been looking outside in the middle of a dust storm, and the AQI is 35,” Perry said. An AQI of 50 or below indicates good air quality.
Part of the forthcoming network, he hopes, is a roll-out of new instrumentation that does a better job of tracking dust concentrations coming off the lake. With improved monitoring, the state could do a better job of helping people protect themselves from the harmful effects of dust.
For example, Perry said, the state has a solid system for alerting the public when smoke from wildfires makes the air unhealthy to breathe.
“We don’t have a similar capability for dust, which means that we don’t have models that can predict when these dust events are going to happen,” he said. “But more importantly, we don’t have alerts to tell us when we’re actually experiencing a dust storm. People can easily protect themselves from the dust if they know it’s there.”
Self-protective measures against Great Salt Lake dust, he said, include wearing N95 masks and staying indoors when concentrations are highest.
This year, a state Democratic representative requested $651,000 in ongoing funding to examine air quality and health impacts resulting from the lake’s dust storms, but just $150,000 was approved by the Legislature.
“We really need to put pressure on the Legislature to let them know that they need to be responsive to the concerns of the people they supposedly represent,” Perry said.
‘Hyperlocal’ factors complicate monitoring
Even where the state can set up PM10 monitoring, there’s no guarantee those sites will capture every dust storm.
Three of the new sites, for example, weren’t running on Jan. 20 because it was outside the typical dust season of Feb. 1 to Sept. 30, Edie said.
“We’re seeing that we’re going to have to extend that time period,” she said.
And there are “hyperlocal” factors that might also affect the monitors, Edie said, like construction near the new instruments at sites close to Brigham City and the Utah State Correctional Facility south of Farmington Bay.
There’s also the complication of dust storms from the west desert, like Salt Lake County saw two weekends ago.
Those storms can deposit dust that gets resuspended when the wind picks up or shifts, Edie said, making it “very difficult and complicated” to tell where the dust is coming from.
The state is set to do extra analysis on filters that collected dust during big events, she said, but it won’t start identifying which ones to send to the lab until June.
Trend data, other available information good for personal planning
Some real-time information is available through DEQ’s Division of Air Quality via sites with instruments that do continuous monitoring, but Edie cautioned that data sometimes has errors when the state recalibrates equipment.
That data and information available through a network that Tellus, a Utah-based company that produces air monitors, has set up can still be good for personal planning, Edie said.
She described the Tellus network, which Salt Lake County makes easy to use through a map, as “low-cost.” The network also only measures PM2.5.
All of the monitoring equipment, whether low-cost or more expensive, struggles under high load, Edie said, but the low-cost monitors also have to “make more assumptions about what type of aerosol or particle they’re measuring.”
They might overestimate the problem, she said, but can still be helpful as a relative check on whether it’s a good idea to take precautions like masking, limiting outdoor exercise or timing when to go outside.
“No matter where the dust is coming from, those are good steps,” she said.
The dust storms are “thankfully pretty temporary,” Edie said, but the state is taking them seriously.
