Strict new air quality standards proposed by the Iowa Department of Natural Resources (DNR) were nullified in early May by the Iowa Legislature.

The rare move followed an outcry from agriculture, business, city and industry interests. The legislators struck down a proposal to impose standards of 150 parts per billion (ppb) and 15 ppb of hydrogen sulfide at any off-site location.

Tim Bierman, chair of the Iowa Pork Producers Association's Public Policy Committee, says the DNR plan was not supported by sufficient scientific evidence. The plan was purportedly based on a joint report by Iowa State University and the University of Iowa.

That report recommended ammonia levels of 500 ppb at the property line and 150 ppb at a residence or public use area. Furthermore, the guideline for hydrogen sulfide was 70 ppb at the property line and 15 ppb at a residence or public use area.

Instead of following those recommendations, DNR used the lowest available numbers and applied them at the closest possible distance from the manure handling operations on the farm, says Bierman. That same approach would be used to test by municipal lagoons and waste treatment systems.

The rule also “puts the cart before the horse,” stresses Bierman. Senate File 2293 intended that the air quality rule be adopted only after a field study to determine if air pollutants from animal feeding operations are “present at a separated location at levels commonly known to cause a material and verifiable adverse health effect.”

Iowa law dictates that state outdoor air quality standards cannot be enforced until Dec. 1, 2004, and after the field study is completed, he says.