No direct links between incinerator, asthma rates

Mayoral candidate Gary SchiffÂ’s statement suggests a connection thatÂ’s hard to prove

Emissions from the Hennepin Energy Recovery Center, or HERC, are currently under review by the Minnesota Pollution Control Agency. Credit: Sarah McKenzie

(Editor’s note: This is a Fact Check column — an occasional featuring digging into the claims made by candidates and other people in public life.)

In an April 3 forum featuring seven candidates for Minneapolis mayor, Gary Schiff, the current Ward 9 City Council member, said he opposed increasing the amount of trash burned in the downtown incinerator.

Schiff wasn’t alone. Four of the seven candidates stated the same position that day. But Schiff went further, suggesting a link between the Hennepin Energy Recovery Center, or HERC, and an increased prevalence of asthma in downwind neighborhoods.

In doing so, he wandered into some highly contentious territory. Schiff never claimed a cause-and-effect relationship, but it’s difficult to show any kind of link between HERC emissions and Minneapolis asthma rates.

HERC is a hot topic this election season because Covanta, the company that operates the waste-to-energy facility, and Hennepin County are proposing to operate it at capacity, increasing burning to 442,380 tons per year. Currently operating at about 90 percent, HERC burns about 365,000 tons per year.

“I do not support the expansion of the HERC burner,” Schiff said on April 3. “The plume models show that it will impact negatively children from the lowest-income neighborhoods in the City of Minneapolis, where particulate matters contribute directly to the rates of asthma that we see right now in inner-city neighborhoods.”

Schiff’s statement tied together two different sets of data: models indicating where pollutants from HERC concentrate and Minnesota Department of Health studies of asthma hospitalizations. A similar approach was taken by Rep. Frank Hornstein [DFL–61A] and former planning commissioner Lara Norkus-Crampton in a recorded discussion posted on the website of Minneapolis Neighbors for Clean Air, a citizens group focused on improving air quality (

Here’s what we know: The asthma hospitalization rate is indeed higher in Minneapolis than the rest of the state, and is particularly high in north and south-central Minneapolis neighborhoods, according to a health department report tracking hospitalizations between 2008–2010.

Air pollution, though, is just one of many potential asthma triggers — as is noted in the report — and the HERC is just one source of air pollution in a city crisscrossed by highways and dotted with industry. Other factors influence asthma hospitalization rates, added health department toxicologist Carl Herbrandson, including whether or not a person has health insurance or a primary care physician.

There’s another problem with Schiff’s statement. The “plume models” he cited came from a June 2007 study prepared in advance of the construction of Target Field, located adjacent to the burner.

That study included what is more appropriately called air dispersion modeling to predict how HERC emissions might interact with Target Field and was never meant to examine how the emissions impact neighborhoods, said Steve Sommer of the Minnesota Pollution Control Agency. Sommer is leading the team preparing an environmental assessment worksheet, or EAW, on the HERC, a step triggered by the proposal to increase burning.

An environmental impact study, or EIS — a type of next-level review that goes more in-depth than an EAW — was completed in the mid-1980s, before the HERC opened, and included air dispersion modeling for a broader area around the facility.

“I would definitely not use that information today,” cautioned Sommer, who said a number of factors have changed since then. HERC’s emissions are cleaner in response to tighter state and federal standards, and downtown construction has changed the airflow around the facility.

More importantly, background levels of air pollution have decreased since the HERC opened. Minnesota’s air is, in general, getting cleaner.

More recent air dispersion modeling for the HERC predicts the highest levels of pollutants will be found within one mile of the burner and at elevations of 10 stories or above. Even in the worst-case scenario, the concentrations of specific pollutants are not predicted to exceed Environmental Protection Agency standards.

Actual readings from downtown monitors show air quality is meeting federal standards.

Sommer’s team is partway through an air emission risk assessment of the HERC, and it’s important to note they have not yet completed their work on particulate matter, the specific asthma threat raised by Schiff. But with the assessment mostly done, Sommer can say “no negative health effects (are) expected to occur” by increasing burning to 100-percent capacity.

Still, Schiff’s statement reflects a more general concern about burning trash, one that’s not uncommon in Minneapolis or other communities with incinerators. Environmental consultant Alan Muller, who previously worked as a consultant for DuPont Engineering on incinerator projects, said there is a “conceptual difference” between the way regulators and environmentalists look at incinerators.

“There [are] no safe levels for any air pollutants,” Muller said, adding that any increase in pollutants also increases the potential risks in the form of asthma, heart attacks and other health impacts. And the evidence suggests people in low-income inner-city neighborhoods near the HERC already are at greater risk for these health issues, he added.

“If we care about these people we should get rid of the HERC,” Muller said.

CORRECTION: A description of Alan Muller’s previous work history was corrected to reflect that he worked as a consultant to DuPont Engineering, not as an engineer.