Billowing clouds of the stuff struck a severe blow to the American heartland during the 1930s, ruining wheat crops and forcing farming families to flee westward.
Apollo astronauts tracked it into the lunar module, its gunpowder-like taste and smell causing them to suffer bouts of sneezing and watery eyes.
Dust is as old as the universe itself.
Now, a new study spearheaded by a University of Miami graduate assistant could help change the protocol by which public health officials measure and determine the risk of exposure to household dust young children face.
"Household dust is a mixture of everything from skin cells, hair, and bacteria to dust mites, dead bugs, soil, and pollen. And what's alarming is that toxic chemicals from everyday products can bind or stick to it," said Cristina Fayad-Martinez, a second-year Ph.D. student in the Department of Chemical, Environmental, and Materials Engineering at the College of Engineering.
"Children are especially vulnerable to dust because they explore closer to the ground and are much more likely to place their hands and other objects into their mouths," she said. "But sadly, very few studies simultaneously report both the mass and particle size of household dust found on children's hands after their natural indoor play activities."
Her study, funded by the Environmental Protection Agency (EPA) and the National Institutes of Health, is one of the first to do so.
To accomplish their task, teams of researchers from three academic institutions collected dust particles rinsed from the hands of 101 children ages 6 months to 6 years old from an equal number of households in Miami-Dade County; Greensboro, North Carolina; and Tucson, Arizona.
The researchers also cleaned homes in the three test sites, using dust wipes and vacuum cleaners equipped with special filters to collect dust samples.
The samples were then tested in a Coulter Counter that measures the size of particles suspended in liquid. Study results found that while "dust loading was impacted significantly by the presence of large particles, smaller particles tended to dominate the contribution towards the surface area of the particles where contaminants can accumulate."
"Those smaller particles typically contain higher concentrations of toxic chemicals than larger particles. And that makes them more dangerous because they can travel deeper into the lungs," Fayad-Martinez explained.
Current EPA guidelines, Fayad-Martinez pointed out, do not yet account for the impact of particle size in exposure estimates. "We believe that has to change," she said. "Those current guidelines for soil and dust sampling may be overestimating dust particle sizes found on children's hands, potentially underestimating children's exposure to contaminants that are enriched in the smaller size fractions."
Multiple hours of video footage taken inside each home proved pivotal to the study. "With it, we were able to document the playtime of the children and show how many times they touched the floor and their mouths," Fayad-Martinez said.
Researchers from North Carolina Agricultural and Technical State University analyzed the video footage, while scientists at the University of Arizona used data to calculate how much dust was being ingested by the children. Fayad-Martinez and a team of students at the University of Miami's College of Engineering led the testing of dust samples.
The three institutions relied on community events, online postings, and partnerships with local organizations to recruit families and to help ensure a diverse group of participants.
The study, "Mass and particle size distribution of household dust on children's hands" is published in a recent issue of the Journal of Exposure Science and Environmental Epidemiology. It is part of a larger effort—the Dust Ingestion childRen sTudy, or DIRT—aimed at augmenting existing data on the exposure risks of household dust.
Future study results will report on the role climate and construction practices play in the amount of dust that accumulates in households.
Preliminary results from their next study indicate that climate plays a much smaller role in the amount of dust that enters a residence, with human habits being "a bigger driver," Fayad-Martinez said.
She has also expanded the study to her native Mexico, sampling homes in her birth city of Puebla, which is located about 25 miles from Popocatépetl, a towering active volcano that has been erupting on and off since 2005, spewing steam, gas, and ash.
"We expected our samples from home in Puebla would be higher in dust concentrations because of their proximity to the volcano and because those households used natural ventilation," she said. "In some cases, it was true. But in most instances, those homes contained similar loads of dust as those households we tested in the U.S."
