Dust Size Matters

Iowa State University researchers found that small dust particles carry more odor per weight and surface area than coarse dust.

Published on: Apr 18, 2006
It's long been understood that dust particles in and around livestock confinement buildings carry odor. But little attention has been given to the connection between the size of those dust particles and the odor emitted.

Iowa State University researchers recently conducted laboratory studies that found small dust particles carry more odor per weight and surface area than coarse dust.

"One of the implications of this research is that as engineers work to develop effective odor controls for livestock operations, we must target fine dust," says Jacek Koziel, assistant professor in Iowa State's agricultural and biosystems engineering department. 

The results of the research project were published recently in the Journal of Chromatography A. Steve Hoff, professor of agricultural and biosystems engineering at Iowa State, collaborated with Koziel on the research and journal paper.

The paper focuses on the lab experiments. But Koziel says the "real-life" implication is that controlling swine dust has the potential to control odor. "And that small particles are carrying a disproportionate fraction of the total odor, while being capable of traveling longer distances from the source," he says.

Three monitors for continuous real-time measurement of airborne particles were placed in a private hog confinement building. Seven sets of swine barn particulate matter samples were collected. The monitors were operated for three months in a 1,000-head swine finishing building.

Fifty different compounds were identified in the sampling. One surprise was that 21 of those had never been reported in previous studies as being present in swine barn dust.

Once the compounds were isolated, an instrument was used that can identify different substances within a test sample. The instrument also is equipped with special software and a sniff port, which is used by panelists trained to evaluate odors associated with each compound.

"The software records aromas and odors caused by each chemical in a sample and records information about the odor intensity associated with each compound," Koziel says. "The analysis conducted is unique because olfactory responses from panelists can be measured compound-by-compound at the same time chemical compositions are evaluated."

The next step was to match these odor-intensity findings with dust particle size. That's how the researchers determined the smallest particles absorb the most odor.

Previous research led by Hoff has shown odor can be reduced by using filters to reduce dust movement. Now Koziel and Hoff hope to find funding for a new project that will build on their past research in both swine and poultry buildings. The proposed field experiment would look for better ways to reduce odor by controlling dust, with an emphasis on controlling the smallest dust particles.