Summer of Sand

Massive dust storms known as haboobs transport toxic particles

By Dan Zukowski

November 2, 2018


Photo by mdesigner125/iStock

It was called epic, historic, and terrifying. A wall of sand a mile high swept across Arizona on July 9, 2018, knocking out power to 100,000 customers. The dust storm kept going for 200 miles, finally petering out in Baja, California. Sandstorms like these carry heavy metals, toxic chemicals, and microparticles from 350,000 acres of open-mine tailings, which get into the lungs, water, and soil of Arizona residents.

From 1955 to 2011, more than 1,500 dust storms were recorded in Arizona. These events were directly responsible for 157 deaths and more than 1,300 injuries, according to a 2016 National Oceanic and Atmospheric Administration report. They can occur in any part of Arizona but are most common along the I-10 corridor from Tucson to Phoenix and in the southwest part of the state. Also known as haboobs, these large dust storms are created by strong downburst winds at the leading edge of summer monsoon thunderstorms.  

Climate change is making them worse.  

“There's more moisture for those storms to work with, and the instability has also increased,” explained Christopher Castro, an atmospheric scientist at the University of Arizona. His research found that monsoon precipitation is becoming more extreme. With more intense storms, the downburst winds are also stronger, creating more dangerous dust storms. 

Mining operations dot Arizona. It’s a state with 100,000 abandoned mines and almost 50,000 active operations digging up coal, copper, gold, lead, silver, zinc, uranium, and other commodities. It’s the waste from these mines that is the focus of a $3.27 million Superfund research program encompassing five colleges at the University of Arizona. Chemical engineer Eduardo Sáez, who has been researching airborne dust from mine sites for eight years, found that the size of these dust particles matter.  

“Very small particles are transported longer distances and are precisely the particles that go into your lungs,” Sáez explained. He’s talking about particles that are 0.3 micron in size, so small that 25 of them could fit inside a human red blood cell. They easily get into our lungs, and they carry trace amounts of arsenic and lead.

report released earlier this year by the Arizona Department of Health Services concluded that breathing the air in the Hayden and Winkelman area could harm people’s health. Hayden, 70 miles northeast of Tucson, is the site of a huge smelter than processes 720,000 tons of copper a year. Children are at risk “for neurocognitive or neurobehavioral effects,” the report states. And at a high school in Hayden, Sáez said he’s found that about half of the small, 0.3-micron particles in the air outside make it inside through air vents and open windows. 

Those heavy metals also fall to Earth and become part of the soil, where many Arizonans grow their vegetables. In 2008, Mónica Ramírez-Andreotta launched Gardenroots to help people living near mine sites understand the risks of planting in these soils. “Gardeners tend to be very connected to their land,” she said. “Community members asked if they could grow food and how much of it could they actually eat.” Sharing results with the participants as soon as possible, she digested the science to its most basic: “You can eat so many cups of kale from the garden a week.” 

Ramírez-Andreotta grew up in Tucson. She loved soccer and art and photography. She’s co-credited by the National Science Foundation with an image of the Whirlpool Galaxy and was a curatorial assistant at Tucson’s Center for Creative Photography. Now an assistant professor in soil, water, and environmental science at the University of Arizona, Gardenroots was the first of two citizen science projects she created to educate and empower local communities. 

“Community members are experts in their own right,” she told me. “They want to protect themselves and their family.” 

Project Harvest, a University of Arizona program in partnership with the Sonoran Environmental Research Institute, launched last year and has trained community team leaders, called promotoras, to acquire water, soil, and plant samples for testing. They’re looking at the safety of rainwater, collected by residents for garden use, in three rural communities and an underserved area of Tucson that Ramírez-Andreotta described as “linguistically and politically isolated.” Results, to be presented bilingually and visually, are due before the end of the year. 

But, says Kara Cook, toxic program director for U.S. PIRG, “This is an issue that affects all people in Arizona.” Dust storms can carry toxic particles many miles. Nogales experienced 84 days in 2016 with elevated levels of PM2.5 particulates (those smaller than 2.5 microns), which pose the greatest health risk. Yuma had 49 and the Phoenix area 27.  

Daniel Tong, an atmospheric scientist at George Mason University, emailed, “Dust storms are linked to asthma, bronchitis, and even premature deaths.” Valley Fever, a lung infection caused by a fungus that lives in southwestern soils, is endemic in Arizona. In areas frequented by sand storms, he found that the infection rate of Valley Fever jumped by more than 800 percent from 2000 to 2011.  

Another finding surprised Tong: “We saw the frequency of dust storms in the U.S. increased at a speed 10-fold faster” than globally. Across American deserts, the frequency of windblown dust storms grew 240 percent from the 1990s to the 2000s. “Climate models predict that, as the earth warms, the region will become even drier in the coming decades. Therefore, we expect to see more dust storms,” Tong added.  

Dry, barren soils help feed these haboobs. Arizona experienced a drought lasting 473 weeks from 2009 to September 4, 2018. Megadroughts—droughts lasting decades—“could become commonplace if climate change goes unabated,” reads a 2016 paper in Science Advances

That makes control and remediation of mine tailings even more critical. Four of the top five toxic emitters in Arizona are the Hayden Smelter and three metal mining operations, according to the EPA’s latest Toxic Release Inventory. Those four alone employ more than 5,000 workers in a state where hard-rock mining is a $4.3 billion business. More large mining operations are on the way, including the 1.5-square-mile open-pit Rosemont copper mine, set to begin construction next year.  

Arizona, the Grand Canyon State, has long been at the nexus of starkly beautiful landscapes and destructive resource extraction. It’s also where demand for the metals that make our technologies work and the mining jobs that feed local families come into conflict with the health of those same families.  

While researchers seek to better understand the grand forces of dust storms and climate change, and the EPA sets up a Superfund Task Force that leaves every Arizona site off its list of those designated for immediate action, Ramírez-Andreotta sees her purpose as protecting the environmental public health of everyday Arizona citizens. “That's my driving mission as a researcher and academic.”