What is a haboob? The science behind the dust blob that swallowed Phoenix
Skies can turn from clear blue to pitch black as a haboob rolls in. Here’s how this wall of dust forms, and what health experts say is lurking within.
Thousands of Phoenix residents were recently engulfed in darkness when a towering wall of dust, known as a haboob, engulfed parts of the city on Monday. The colossal dust storm plunged the city into near-zero visibility and was quickly followed by severe thunderstorms that left more than 60,000 Arizonans without power.
Often seen during monsoon season, haboobs are common in arid regions such as the southwestern United States, the Saharan Desert, and the Arabian Peninsula.
Here’s the science behind haboobs and how they impact our health and planet.
What is a haboob?
Haboobs are dense walls of dust kicked up by thunderstorms, and can be several miles long and several thousand feet high. Haboobs can travel hundreds of miles depending on the area’s geographic terrain.
“A haboob is a dust storm, but not all dust storms are categorized as haboobs,” says Sean Benedict, lead meteorologist at National Weather Service in Phoenix. Benedict says most of the dust storms in the southwestern U.S. are haboobs. They differ from other dust storms by their trigger, appearance, and duration. The name "haboob" comes from the Arabian word ‘hab’, meaning ‘to blow’ and has been used by the meteorological community for almost 100 years.
Haboobs are common during the North American monsoon, a seasonal high-pressure pattern that forms when summer temperatures cause a shift in wind patterns that draw in moisture from the Pacific Ocean and the Gulf of California. This moisture helps fuel thunderstorms in the area that then trigger dust storms like haboobs.
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“With the high pressure in place, the storms go up and they usually don’t move much,” says Benedict. “Eventually, they collapse and produce downbursts, or microbursts.”
A large cluster of thunderstorms can continuously produce these downbursts, generating winds that are strong as 50 to 80 miles an hour. These strong, continuous winds create the conditions for haboobs to appear as strong winds fling loose earth off the ground.
“As these rocks fly up into the air and slam down into the ground, they release two or three more tiny rocks. It’s a process called saltation and it's the basis for how these storms like haboobs develop,” says Kyle Rine, laboratory coordinator and researcher at the University of Arizona. “You have strong winds lifting up these particles and slamming back down, and it very quickly produces these huge walls of dust.”
It’s a chain reaction that sets the stage for where haboobs strike most often. Nowhere is more evident than along Arizona’s highways.
“The I-10 corridor between Phoenix and Tuscon is a very dust prone location and that's where most of these storms come from,” says Benedict.
Environmental impact of haboobs
Experts say as our climate continues to change, we can expect an increase in the frequency and the magnitude of extreme dust storms like haboobs.
“With climate change, we are observing an increase of all factors and drivers that cause these types of events,” says Hesham El-Askary, a professor of earth science at Chapman University’s Schmid College of Science and Technology and an author on a 2019 United Nations climate report that outlined the global state of desertification.
“Extreme winds, hot days, drier summers, and high humidity can lead to loose soil prone to suspension,” he says.
(Extreme heat is the future. Here are 10 practical ways to manage it.)
El-Askary adds that these changes will be seen more globally in the world’s most hyper-arid regions, a classification the report gave to parts of the the American Southwest.
While the climate determines the conditions that give rise to dust storms like haboobs, these storms can also impact the climate. A 2023 study supported by National Science Foundation found that atmospheric dust from deserts had a slight overall cooling effect on the planet, blunting the full amount of warming caused by greenhouse gases.
Haboobs can create near-zero visibility and Rine says nearby wildfires might worsen that effect. Wildfire smoke settles and becomes re-aerosolized when the monsoon starts.
(Is ‘weather whiplash’ our new normal?)
Health impacts of haboobs
Haboobs can raise the risk of contracting respiratory infections, including the fungal infection Valley Fever. Strong winds stir up infectious spores and make them easier to inhale, says Stefania Papatheodorou, an associate professor at Rutgers School of Public Health. Around 20,000 cases are reported annually in the U.S.
The University of Arizona’s Rine notes that in the southwestern U.S., the leftovers of now defunct mines, contaminated with metals like lead and arsenic, can be swept up by a haboob.
“If you happen to be by one of these legacy tailings piles, a haboob could be extremely dangerous because it's spreading that poison to fields, animals, and people,” Rine explains.
It’s even possible for contaminants to stay in the air for days after a haboob has passed.
“If it rains after a haboob, it will clean out all those particles in the air. But sometimes it’s so hot that the rain from these storms won't reach the ground,” says Rine. “There can be an accumulation of dust that stays for a day or two, and that size of particle is especially dangerous for us to inhale as it stays in your lungs.”
(Here’s what extreme heat does to the body.)
Repeated exposure to this dust can lead to chronic respiratory, cardiovascular, and inflammatory health conditions. Populations living in areas frequently affected by haboobs face cumulative exposure to pollutants in the dust, according to Papatheodorou.
How to stay safe in a haboob
Check the National Weather Service for dust advisory and dust warnings in your area.
If you’re driving, Benedict says to “pull aside and stay alive.”
“Turn your lights off because cars behind may just be following you, still going at a high rate of speed. That's how accidents happen,” he says.
If you are immunocompromised, Papatheodorou says avoiding this dust is crucial. These storms can trigger or worsen symptoms in people with pre-existing respiratory diseases.
Stay indoors and use high-efficiency HVAC filters or HEPA air purifiers to reduce exposure to harmful particles and potential pathogens. Wearing a mask outdoors can also help protect your lungs from particles that may be floating in the air.
