Iowa Supreme Court, No. 15-1942 · Decided May 12, 2017 · Class certification affirmed
In Freeman v. Grain Processing Corporation, the Iowa Supreme Court affirmed class certification on behalf of thousands of residents living near a corn wet milling facility in Muscatine, Iowa, who alleged that decades of smoke, particulate matter, and odor emissions from the plant’s dryers and boilers interfered with the use and enjoyment of their properties. Dr. Rosenfeld’s AERMOD dispersion modeling and wind rose analysis were central to the plaintiffs’ case for treating the claims of thousands of residents as a single class.
What Dr. Rosenfeld Contributed
Dr. Rosenfeld modeled the dispersion of three emission types — volatile organic compounds, particulate matter (PM10), and sulfur dioxide — using each as a scientific proxy for the odor, smoke, and haze residents reported. He used AERMOD, the EPA-approved dispersion algorithm that incorporates wind direction, wind speed, temperature, humidity, precipitation, and terrain obstructions, to estimate where and how far emissions traveled across the class area.
He then developed a wind rose analysis based on the sixteen cardinal wind directions to quantify, property by property, how many hours each parcel spent downwind of the facility — what the opinion repeatedly calls “direct hits.” This converted a qualitative complaint about smoke and odor into a reproducible, property-specific exposure metric comparable across the entire class, which the plaintiffs then used to build a per-property “concentration total” damages formula.
“Dr. Rosenfeld’s data showed the presence of the same pollutants frequently and repeatedly on every property in the class, and the presence of those pollutants at properties closely surrounding the properties of the testifying normal persons.”
— Iowa Supreme Court, summarizing Dr. Rosenfeld’s air dispersion evidence
What the Court Said About the Modeling
The district court used Dr. Rosenfeld’s quantified exposure gradient — comparing a concentration total of 317.21 for the plaintiff closest to the facility against 71.50 for the plaintiff farthest away — to divide the class into “close proximity” and “peripheral proximity” subclasses.
“Plaintiffs’ air dispersion analysis yields results one would expect — properties in close proximity have comparable ‘Concentration Totals’ and direct-hit hours.”
— District court, quoted with approval by the Iowa Supreme Court
On appeal, the defendant argued the model improperly combined three pollutants into one linear score and failed to account for time residents were away from home. The Iowa Supreme Court rejected these as certification-stage objections, holding they concerned the model’s ultimate reliability — a question for trial.
“GPC’s objections at this stage to Dr. Rosenfeld’s model are likewise unavailing.”
— Iowa Supreme Court
“GPC’s defense that Dr. Rosenfeld’s study is ‘unrepresentative or inaccurate’ is itself common to the claims made by all class members.”
— Iowa Supreme Court
Outcome
The Iowa Supreme Court affirmed class certification, preserving the two exposure-based subclasses defined using Dr. Rosenfeld’s modeling — confirming that AERMOD dispersion modeling paired with a wind rose exposure analysis can establish that common questions of exposure and harm predominate across a large, dispersed class.
References
- Freeman v. Grain Processing Corp., 895 N.W.2d 105 (Iowa 2017).
- Freeman v. Grain Processing Corp., 848 N.W.2d 58 (Iowa 2014).
- Comcast Corp. v. Behrend, 569 U.S. 27 (2013).
- Tyson Foods, Inc. v. Bouaphakeo, 577 U.S. 442 (2016).
- Miller v. Rohling, 720 N.W.2d 562 (Iowa 2006).
Provided for general informational purposes on air dispersion modeling in environmental litigation. Not legal advice. Case citations and quoted excerpts are drawn from the published Iowa Supreme Court opinion and should be independently verified against the official reporter before reliance in any filing.