The researchers spent a year studying sampling processes to determine the number of organisms that might exist on surfaces following a biological attack with agents such as anthrax. They found more deadly spores remaining after decontamination than previously believed.
"We evaluated Centers for Disease Control and Prevention recommendations for sampling methods and discovered all current methods underestimated the number of spores ... actually present on surfaces," said lead researcher Gary Brown.
The scientists found none of the current sampling methods very efficient.
The swab system collected 40 percent of the spores, leaving 60 percent behind. The wipes collected 28 percent, leaving 72 percent.
But researchers said the biggest surprise was the vacuum method collected only 20 percent of the spores, leaving 80 percent on the surface.
"Before this study, the vacuum method was the most highly recommended sampling method by the CDC," Brown said, adding that as a result of the study, the CDC no longer even recommends that method.
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