Scientists are predicting that the frequency of dust storms, on the rise in the last few years, will continue to increase. Some have also suggested that these storms might well be carrying a more hazardous payload than meets the eye. Among the dangers that experts say are blowing in the wind: asthma triggers, toxic chemicals and infectious disease.
"We are experiencing heat waves and drought across the country. And we anticipate more dust being blown into the air," said William Sprigg, a dust storm expert at Chapman University in Orange, Calif. "Anything that is loose on the soil is going to be picked up by these storms."
A look back 80 years to the Dust Bowl could offer a hint of what's to come. According to a scientific study published in October 1935, Kansas experienced its "most severe measles epidemic," as well as abnormally high rates of strep throat, respiratory problems, eye infections and infant mortality during the intense dust storms that struck from February to May of that year. The researchers highlighted the potential for both short- and long-term health troubles associated with the dust, but stated that they couldn't find any pathogens in their dust samples.
The same regions that were affected then -- from New Mexico to the Dakotas -- may be at greatest risk from dust storms in the future, said Dale Griffin, an environmental health microbiologist with the U.S. Geological Survey. Griffin points to the unsustainable strip farming methods of the 1920s and '30s, and consecutive years of desiccating heat and high winds that combined to devastate a large swath of the country. And he agrees with Sprigg that conditions today could favor more of the same. This July was the hottest month on record, which has worsened an already devastating drought that experts say has been exacerbated by poor farming practices.
"Because of climate change, it looks like we're possibly shifting into a phase similar to what occurred in the 1930s, or worse," said Griffin. "We may be seeing an increase in dust storms that could affect human health."
Texas and Oregon are among the regions already seeing a rise in such events. Haboobs -- severe thunderstorms that kick up massive amounts of dust -- have blanketed Phoenix more frequently in recent years, including one headline-grabber last July.
The most well-understood health threat from these storms is the dust particles themselves. If small enough, they can slip past a body's natural defenses -- nose hairs, for example -- to infiltrate and damage one's respiratory system. Now scientists are learning about an array of harmful substances that may also hitch a ride: arsenic and other heavy metals, agricultural fertilizers and pesticides, as well as a laundry list of bacteria, fungi and viruses.
In the southwest, one airborne hazard gaining significant attention is valley fever. A debilitating and sometimes fatal infection, it is contracted from fungal spores naturally present in the region's soil. Could dust storms send these spores into the air and into the lungs of residents? Sprigg is currently investigating a possible connection between last year's haboobs and subsequent infections. Such links haven't been well studied, he said, because people had assumed that the sun's ultraviolet rays would kill any airborne microbes. But it seems that the dust particles themselves provide a shield for their passengers, explained Sprigg, who is collaborating on a system to predict when dust storms will occur in order to alert area residents, schools and traffic cops.
Other parts of the world are even more familiar with dust storms and their dangers.
The region of Africa between Senegal and Ethiopia has long been subject to severe meningitis epidemics, which research now suggests is at least partially linked to dust storms. In Asia, asthma and other children's respiratory problems have been found to be more common the week after dust storms.
Perhaps most notorious for pestilent dust is the Middle East.
Navy Capt. Mark Lyles, of the Center for Naval Warfare Studies at the Naval War College in Newport, R.I., found high levels of aluminum, heavy metals, as well as bacteria, fungi and viruses in samples of the ultrafine, and therefore lung-penetrable, Kuwaiti and Iraqi dust. He suggested that parts of this cocktail may be responsible for the mysterious Gulf War Syndrome suffered by veterans of the Iraq War, as well as the high rates of health problems among soldiers returning from the dusty theater of war today.
"A lot of this [research] will translate to the U.S., especially with the mineralized dust we see in the southwest," he said.
These dust storms overseas don't pose problems merely for those who live in those regions, however.
"That dust gets blown all around the world," said Sprigg. "A storm in the Gobi or any Asian desert can bring dust to California, Arizona -- even all the way to Boston."
Just last month, Saharan dust hazed Florida skies.
Between 500 million and 5 billion tons of dust moves around the planet every year, explained Griffin. And each gram of that dust -- about as much as you can pinch between your forefinger and thumb -- carries millions of bacterial cells. Griffin estimates that there are enough microbes traversing the globe to "form a bridge between Earth and Jupiter several cells wide."
Griffin said his research has also found that dust can move a "very diverse microbial community vast distances in Earth's atmosphere." While this worldwide transport is not all bad -- a lot of plants and fisheries derive nutrients from the foreign dust -- a significant portion of the blown organisms, he said, are "capable of causing disease."
The Huffington Post reported last year on the possibility that Kawasaki disease could travel internationally via wind-blown dust. And Taiwanese scientists suggest the similar long-range transport of bird flu.
The same phenomenon might have the potential to spread a disease like valley fever beyond the southwest, according to Sprigg.
Sprigg mentioned a further danger posed by dust storms in the dry region: their potential to self-propagate. As dust settles on the Rocky Mountains, it speeds up the snowpack's melt, which then depletes the amount of water available in the summer. The result could be a worsening drought and increased chances of further dust storms. "It's a bad cycle," he said.
It's one that researchers in the 1930s never wished upon future generations. "It is hoped that dust storms," they wrote, "experienced almost daily for a period of 3 months will never occur again."