November 13, 2009

Study Examines Origins Of Dangerous Dust

The bane of every good housekeeper's existence is that relentless, untiring foe known as dust.  Researchers now say they have created a computer model that may help us to understand where it all comes from and why we can never seem to get rid of it.

In most homes, scientists say that the majority of dust sneaks in through the air from outdoors and is composed of a variety of offensive ingredients such as dead skin cells, soil and even toxic substances that drift in from contaminated waste sites.

In order to determine how dangerous contaminants such as arsenic are able to latch on to dust particles and find their way into our abodes, scientists at the University of Arizona turned the common phenomenon of dust accumulation into a series of complex mathematical equations which they were then able to graph in a computer model.

Though the Arizona researchers are by no means the first to study dust, their study is unique in that they decided to focus exclusively on the larger airborne particles that are more likely to cling to your hands and even be ingested.

The team found that more than 60 percent of household dust appears to originate from soil tracked in from shoes and airborne particles from outdoors. The other 40 percent is a mixture of dead skin, pet dander, fibers from carpets and upholstered furniture.

It is the outdoor-based dust, say the researchers, that can contain potentially dangerous traces of lead, arsenic and other unpleasant substances. They estimated that as much as 60 percent of the arsenic found in floor dust, for example, drifts in through the surrounding air, while the rest comes from tracked-in soil.

In the next phase of the study, the researchers compared the results of their model with data collected from households across the Midwest by the U.S. Environmental Protection Agency.

The team believes that their computer model may prove useful for communities that have to deal with a hazardous waste site cleanup in their vicinity.

"It's pretty difficult to figure out how much you need to clean the soil to protect people in their homes," said Paloma Beamer, an assistant professor at the University of Arizona's College of Public Health.

"This model will help in identifying what are the appropriate levels to clean the soil to."

Beamer also explained that if the high percentage of airborne contaminants proves to be a common phenomenon for regions other than just the Midwest, hazardous waste cleanup crews may prove more effective if they develop techniques for preventing hazardous contaminants in the soil from becoming airborne, rather than simply trying to remove contaminated soil.

The results of the group's study were published in the Nov. 1 issue of the journal Environmental Science & Technology.


On the Net: