Filtering air entering swine barns has proven to reduce some disease exposure, including porcine reproductive and respiratory syndrome. Now, filtering the exhaust air is proving beneficial as well.

Biofilters used for odor mitigation also are beneficial in disease control, points out Mike Brumm, Brumm Swine Consultancy, Mankato, Minn. “As the industry continues moving toward PRRS eradication, we will be using more biofilters over the exhaust air,” Brumm says. “It has been shown that filtering exhaust air through the media typically found in biofilters, such as wood chips or lava rock, is effective in knocking down PRRS virus.”

The practice would be particularly beneficial in concentrated production areas. “With the many sources of pigs in hog-dense areas, the amount of PRRS virus being shed can increase the chance of transmission,” Brumm says. “We’ll see increased use of biofilters, not just for odor mitigation, but also because they reduce airborne disease virus.”

South Dakota State University researchers have shown that biofilters can be effective in reducing PRRS virus spread. But they may help reduce exposure of other diseases such as Mycoplasma pneumonia and swine influenza. “A vertical biofilter that uses wetted wood chips to filter the exhaust air from swine facilities and provide ventilation air residency time of  five seconds was tested for its ability to remove the PRRS virus from the air,” according to the researchers. “When air contaminated with the PRRS virus at levels representative of those found in a swine building was introduced into the biofilter, the exhausted air tested negative for the PRRS virus.”