by Michael Clancy, Arizona Republic News, July 26, 2012
Giant monsoon dust storms that roll across the Valley and coat everything in a fine film of dirt are becoming more frequent, according to the experts. That means more deadly accidents, more harmful pollution and more health problems for people breathing in the irritating dust particles.
But one leading researcher says there also needs to be a lot more study of the effects of the tons of dust being kicked up into the air, especially the hidden health costs for millions of people living in Arizona’s dust zone.
“We already know the cost of these storms in general,” said William Sprigg, a research professor in the University of Arizona’s Institute of Atmospheric Physics, who is working on ways to predict the storms. “I would like to see a much more thorough examination of the effects of the dust on the region.”
That is particularly pressing because some scientists are predicting more frequent and larger dust storms as a result of climate change, which one environmental expert says will cause more powerful and more erratic weather patterns in the Southwest.
Sprigg notes that potential health problems go far beyond common respiratory ailments. Dust storms carry a noxious mix of fungi, heavy metals from pollution, fertilizers, stockyard fecal matter, chemicals and bacteria, which can cause cardiovascular disease, eye diseases and other illnesses.
And while bigger, more frequent storms are only likely to increase the number of people suffering from diseases that health officials know are linked to dust, and possibly amplify their effects, medical science still does not have an accurate accounting of the full effects of breathing those pathogens.
Few statistics
The phenomenon is hardly new, but the impact hit home a year ago, when a major dust storm [a haboob] — the largest many observers have ever seen — rolled through Phoenix on July 5, 2011.
That storm spawned a wall of dust almost 1.5 miles high and 100 miles wide that deposited an estimated 40,000 tons of sand and dust in just two hours. It looked like something from a science-fiction movie and was partly blamed on drought-parched ground.
Dust storms typically develop when cold air in thunderstorms plummets to the ground, driving in front of it a wall of dust.
But it is not just giant dust storms that pose a problem. Starting last Saturday, the Phoenix area saw dust storms three days in a row, which is relatively rare. The maximum wind speed at Phoenix Sky Harbor International Airport during Saturday’s storm was 51 mph, nearly the same as it was for last year’s big dust storm.
Sprigg is working on a modeling system that can accurately predict dust storms. While it is not yet ready to go public, he said, looking back at the July 5 dust storm, “We were able to predict that two days in advance.”
Reliable predictions would allow people, especially those who are particularly vulnerable due to lung disease, to take precautions, he said.
Few records are kept on dust storms in the area, apparently. The National Weather Service issues warnings about them but does not keep records in the same way it does for temperature or precipitation.
Most people, including Arizona state climatologist Nancy Selover, use their own recollections.
“I think they are more common the last two or three years,” she said, blaming the ongoing drought and an increase in “extreme heat events,” warnings issued by the Weather Service when temperatures soar.
“There are no real good statistics on dust storm frequency,” said Sprigg. “I think we are seeing more large ones.”
Effects of dust
Last Saturday’s storm felled tree limbs and power poles, and power outages affected 9,000 Salt River Project customers.
Traffic accidents are common in dust storms, many involving fatalities. Sprigg’s research shows that between 2001 and 2005, dust storms were responsible for 44 deaths in 2,323 traffic accidents in New Mexico, and 15 deaths in 614 accidents in Arizona.
Those injuries and deaths are the highly visible and extreme impact on residents. But dust storms have serious health effects on people with chronic lung disease, said Stacey Mortenson of the Arizona Lung Association. Even healthy people can find themselves in an emergency room with breathing problems, she said.
Then there is valley fever, a sometimes fatal ailment caused when spores of the Coccidioides fungus, which is present in desert soil, is thrown into the air and breathed in.
Dr. John Galgiani, who heads the Valley Fever Center for Excellence at the University of Arizona, said the state has almost 70% of valley-fever cases reported nationally.
He said incidence was up between 2010 and 2011 by 36%, but he cannot say exactly why. Dust storms and lack of precipitation can combine to kick the spores into the atmosphere, but the increase might also be attributed to other causes. It might be simply that with more awareness, more people are being diagnosed.
Research is ongoing, he said, into all aspects of the valley-fever fungus, and more is needed on such questions as whether the fungus spores are localized or widespread, why spikes of illness follow some dust storms and not others, and what effect rainfall has.
On average, each year 150,000 people contract valley fever nationally, according to research by Galgiani and others. About 30 people die annually in Arizona from valley fever.
Sprigg said the relationship between blowing dust and human health is understood in bits and pieces throughout the world, but it can be difficult to pin down in a comprehensive way. Funding is scarce and technology not up to date enough to conduct routine soil sampling and analysis, he said.
He is working with the Weather Service and health agencies, using NASA satellite imaging and other tools, to predict dust storms in the future.
Possible reasons for storms
One result could be a system to map dust storms and subsequent respiratory distress, ultimately allowing health and environmental officials to know what to expect so they can issue early warnings to populations at risk for dust-related health complications.
“They have a tremendous economic and social impact that has been very, very difficult to nail down,” Sprigg said. “But we know enough now that we can tell people a lot more about what they are being exposed to.”
Sprigg said less-obvious effects — like loss of topsoil, abrasive effects on solar and wind power installations and damage to vehicle finishes from blowing dust — pile up. And no one has come up yet with a comprehensive study of a dust storm’s full impact, or how it might be mitigated.
Nor has research been completed on whether global warming is directly related to prevalence and severity of dust storms, although the conclusion for those who accept man-made causes for climate change seems obvious.
Bill DeBuys, a New Mexico author and conservationist, says climate change must be considered as part of the equation.
“Greater heat in the atmosphere is like a ballplayer on steroids,” he said. “Storms can be more powerful and more erratic.”
DeBuys, whose latest book is called A Great Aridness: Climate Change and the Future of the American Southwest, said the effects of climate change “are a one-way train.”
“People in Phoenix can expect more and more dust storms if these issues are not addressed,” he said.
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