Proximity to hog farms does not affect air quality in neighboring residences as much as the activities that take place inside the homes. according to a new Iowa State University (ISU) study that measured air quality near hog farms in Iowa   The study was funded in part by the Pork Checkoff.

“Pork producers try to be good neighbors by using new technologies and methods to control odors,” said Craig Christensen, a pork producer from Ogden, Iowa, and member of the National Pork Board.  “Studies like this validate these efforts and indicate that we’re making headway.”

The 16-month air-quality study measured concentrations of ammonia and hydrogen sulfide on farms and neighboring residences in Iowa.  ISU’s Department of Agriculture and Biosystems Engineering found that in this study meteorological factors such as wind speed and solar radiation affect the concentration of hydrogen sulfide and ammonia more than operation size  or type of manure storage used on the farm.

“This is great news for us as pork producers and for our neighbors,” said Christensen, who runs a 2,000-sow farrow-to-finish operation.

“This study follows another project by the Iowa Department of Natural Resources that shows that pork production does not create odor that should require special considerations for schools, churches or other public gathering places, under Iowa law,” the Iowa pork producer said.

Running the Numbers

The study, which was conducted in 2004 and 2005, shows that an increase in the concentration of hydrogen sulfide measured on the farm does not show a similar increase in concentration inside nearby residences, unless residences are located less than 0.4 mile (2,149 feet) from the farm and climate conditions are such that low wind speed and little solar radiation are present.

Even under these conditions, hydrogen sulfide concentrations inside a residence located less than 300 feet from the largest operation in the study were recorded at levels more than 50 percent lower than the level currently set by the sTaste of Iowa as one with potential health effects.

“As a resident of Iowa, I’m one of the most interested parties in this study,” said Christensen, who finishes nearly 40,000 pigs per year. “I want to preserve the quality of life and health in Iowa.”  

Lifestyle Impacts Air Quality

The study also revealed that ammonia concentrations inside residences tend to be more concentrated than ammonia levels in the air outside residences or at the property line of a hog farm.  The study’s authors said evidence suggests that ammonia levels may be related more to inhabitants’ lifestyles, including smoking cigarettes and having indoor pets, than to the residence’s proximity to a hog farm.

The results support a previous study conducted by the Department of Health and Human Services in Missouri in 2003.

Christensen plans to continue looking for ways to enhance his farm’s odor control strategies, which currently include a 5,000-tree shelterbelt and windbreak and injecting manure only twice a year in the spring and fall.  “I think it’s important that the Pork Checkoff continues to fund swine odor research,” he said.