Several states are looking at or have imposed air-quality standards for hydrogen sulfide and other emmissions. But Iowa is most recently the one in the hot seat. Focusing only on livestock operations – read that swine operations, the Iowa Department of Natural Resources is considering an air-quality standard for hydrogen sulfide at 15 parts per billion emitted from any livestock operation.

The level would be averaged over one hour and could not be exceeded more than seven times in a year.

“We are concerned that this standard may be inappropriate,” says Christina Gruenhagen, Iowa Farm Bureau Federation's public affairs counsel. “We don’t know if there are health risks caused by livestock operations or if there are just occasional annoyances. The DNR set the number for hydrogen sulfide, but many reputable sources have vastly different standards.”

A University of Iowa/Iowa State University study group recommended standards for hydrogen sulfide and ammonia for ambient air near livestock operations in February 2002. They identified 15 ppb for hydrogen sulfide and 150 ppb for ammonia, both measured at a residence or public-use area.

However, new data indicate that the universities' assumptions were inaccurate and may be more rigid than necessary. Also, Iowa State researchers have pulled their support from the joint report.

Scientists now say that both gases are not present at the same hours of the day. Nor are they present 24 hours a day, 7 days a week as the standard assumes. What's more, the DNR's own air-quality monitoring data shows that the gases are not present in equal concentrations.

“According to research, human-health effects occur at much higher levels than the joint university report indicates,” explains Gruenhagen.

She says federal agencies, such as Centers for Disease Control and the Agency for Toxic Substances and Disease Register (a branch of the U.S. Department of Health and Human Services), have higher standards than Iowa is proposing.

Adding to the controversy was the release of a University of Iowa study attempting to link increased asthma among Keokuk County youth to swine confinements. The study indicates a 16.7 percent rate of asthma among children– nearly triple the national rate.

Yet, a university official called the rate “comparable to Midwestern cities of Minneapolis and Chicago. Living in rural areas is not protective for asthma.”

So, what should the hydrogen sulfide standard for Iowa be?

“The real question is how the standard is developed," says Gruenhagen. There needs to be science behind it, science that reflects properly measured ambient air quality and is based upon levels known to cause adverse health effects.”

This is round two in Iowa's attempt to set air-quality standards for agriculture. In 2002, DNR officials recommended and the Iowa Environmental Protection Commission approved, standards for hydrogen sulfide at 15 ppb and ammonia at 150 ppb for agriculture and other businesses.

The Iowa Legislature rejected those standards, saying the DNR failed to follow directives to measure ambient air at separate locations to determine if rural Iowans are being harmed. If health effects are indicated, then standards should be set.

Now, the DNR has proposed a standard for hydrogen sulfide only, and only for agriculture– other Iowa businesses are excluded.

The comment period on the proposed standard runs through April 8. Depending upon public comment, the DNR may modify, reject or propose the standard to the EPC for adoption in early summer.

Political pressures will come into play on both sides of this issue. The outcome would be tough to call for even the most adventurous gamblers.

Iowa Farm Bureau Federation