Driving south on Redwood Road two weeks ago, Kevin Parke watched as a wall of brown dust swept across the Salt Lake Valley, swallowing the Wasatch Mountains and blanketing the familiar landscape in a haze.

By the time he made it home to Salt Lake City’s Rose Park neighborhood, a layer of grit coated his truck. His wife and daughter, who both have asthma, are among the residents most vulnerable to the spikes in airborne particles that come with dust storms.

For Parke, chair of the Rose Park Community Council, dust settling over the neighborhood is nothing new. But he said the July 8 dust storm, fueled by winds sweeping across the exposed lakebed of the Great Salt Lake, was unlike anything he had seen.

“It was eerie,” said Parke, who has lived in Rose Park for more than 25 years. “That was the worst one I recall seeing.”

The storm renewed concerns, Parke said that dust from the shrinking Great Salt Lake is adding to air quality challenges in communities that have long borne the brunt of pollution.

“You definitely feel it,” Parke said. “I’ve had two friends over the years that have been told by their doctor, ‘You got to move somewhere with better air, or you’re going to be on oxygen.’”

Researchers say the storm briefly pushed airborne dust to dangerous levels.

Kevin Perry, an atmospheric sciences professor at the University of Utah, said concentrations of PM10 — airborne particles smaller than 10 micrometers in diameter that can be inhaled deep into the lungs — reached about four times the level considered healthy.

Although dust storms often linger for several hours, Perry said July 8’s was “a quick hitter,” with the highest concentrations lasting roughly an hour.

But even a brief spike can be harmful, he said. Perry, who has studied the effects of Great Salt Lake dust for a decade, said arsenic is among at least 13 contaminants researchers have identified as potential concerns in sediments around the lake.

When that dust is lofted off the exposed lakebed during high winds, exposure to spikes in PM10 can make it harder to breathe and increase the risk of heart attacks and strokes, especially for people in vulnerable groups, Perry said.

“But at the concentrations that we had [two weeks ago], it could really impact anybody,” he said. “When I think about Great Salt Lake dust hazards, I think about dust storm events that can send people to the ER or cause death. And I think about really long-term chronic exposure that can theoretically lead to increases in cancer.”

Once larger than Rhode Island, the Great Salt Lake has lost more than half its water, exposing roughly 800 square miles of lakebed. As those sediments dry, winds can lift dust into the air, carrying a mix of minerals and contaminants.

About 9% of the exposed lakebed — roughly 70 square miles — acts as dust hotspots, Perry said. Those areas lack vegetation or a protective crust to hold the fine particles in place, allowing winds stronger than 25 mph to loft them into the air.

The Utah Division of Air Quality estimates the lake generates three to eight major dust storms each year, Perry said. But that figure doesn’t capture the smaller dust events that aren’t as easily tracked.

Perry estimates those occur between 30 to 60 times a year, sending plumes of dust into nearby communities even when they don’t rise to the level of a major storm.

Over the past three years, a Utah Department of Environmental Quality monitor near Salt Lake City International Airport recorded at least one hour with PM10 levels above 150 micrograms per cubic meter on 106 days.

While some of those days saw high PM10 levels due to wildfires or for other reasons, the EPA’s Air Quality Index says that’s the threshold where pollution begins posing greater risks to sensitive groups over 24 hours.

On 26 days, concentrations topped 425 micrograms per cubic meter for at least one hour, reaching the EPA’s hazardous threshold. During the July 8 dust storm, the airport monitor peaked at 665 micrograms per cubic meter.

Tracking the dust

But researchers still do not have a complete picture of where all that dust travels or how much pollution communities are exposed to, Perry said.

Communities north of Salt Lake County likely saw the greatest dust exposure during the July 8 storm, Perry said but Utah has historically lacked enough PM10 monitors to measure how much Great Salt Lake dust reaches those areas.

Existing monitors are concentrated south of the lake, Perry said, even though only about a quarter of the lake’s windblown sediment typically travels that direction. Much more blows into Davis and Weber counties, he said.

After years of public pressure, the Utah Legislature last year funded a network of new dust monitors around the Great Salt Lake.

The network will extend from Logan to Sevier Dry Lake near Delta and also track dust blowing from the west desert, giving state officials a clearer picture of how often dust events occur, where plumes travel and what they carry.

As air-quality officials work to better understand the makeup and frequency of these events, Daniel Tuutau, chair of the Poplar Grove Community Council, said residents also need a way to know when dangerous dust is headed their way.

A warning system, he said, could help west-side communities that already struggle with poor air quality understand when they should limit time outdoors.

“I think it only makes sense that we have some sort of warning system for us to know that ... is this dust cloud coming?” Tuutau said. ”And second of all, if it is coming, how dangerous is it? How deadly is it?"