Gas and Dust Prove Dangerous Relations

by 5m Editor
12 March 2008, at 11:03am

AUSTRALIA - New research has reinforced the danger of dust and gas emissions in livestock buildings. Apart from the noxious smell, particles smaller than 2.5 micro metres can penetrate the deepest areas of the lungs and cause respiratory disease.

The studies, reported by ABC Science News, were carried out at Department of Agricultural and Biological Engineering at the University of Illinois at Urbana-Champaign. They among the first to quantify the relationship between dust and gas emissions.

The research, which was recently published in the journal Biosystems Engineering investigated the dust from livestock buildings - cattle, chickens and pigs - and found that the dust originates from feed, manure, bedding, soil and the animals' dry skin.

Co-author Jongmin Lee, a researcher at the University of Illinois, Urbana-Champaign, says weak van der Waals forces cause gas and dust molecules to bond. The resulting attraction is weaker than most chemical bonds, but it's enough to keep the gas stuck to the dust. The gas can also separate, or desorb, from the dust.

"The reverse of adsorption, desorption, is the transfer of gas from dust particles to the surrounding air, and the principles are the same as for adsorption," says Lee.

And heat can permit the gases to become volatile and desorb. Lee and colleague Professor Yuanhui Zhang created a closed cylinder device that introduced heat and then allowed them to measure the gas released from dust collected from farm barns, pipelines and exhaust fans in Illinois. They focused on ammonia, one of the smelliest gases animals produce.

Based on their findings, laying hens and pigs produce far more ammonia dust than cattle do. The researchers attribute this to the way the animals are housed. The pigs and hens were intensively managed with mechanically controlled ventilation.

Human Implications

Aside from the stink problem, the gassy particles may pose human health risks.

"Particles smaller than 10 micrometres can penetrate into the large upper branches just below the throat where they are caught and removed by coughing and spitting or by swallowing. Also, particles smaller than 2.5 micrometres can get down into the deepest portions of human lungs and can cause respiratory disease," says Lee.

There is also a minor threat that contained buildings could explode due to the build-up of gassy dust.

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For more information on BioEngineering/environment visit www.BEE University of Illinois

Further Reading

- To view an abstract of this research paper click here.

5m Editor