City of Iowa City news release
In response to public questions received in 2024 regarding odors believed to be related to industrial activity on Iowa City’s east side, the Iowa Department of Natural Resources (DNR) and City of Iowa City requested the U.S. Environmental Protection Agency (EPA) conduct further investigation.
While the City enforces local ordinances and codes, it does not have the authority to regulate air quality. The public questions led to the request for an EPA assessment to help identify the source of the odors and determine any potential health impacts.
The EPA conducted unannounced air quality testing using a mobile air monitoring system called DART (Data Acquisition in Real Time). Over several days, the system collected samples at varying times while traveling through industrial areas and nearby neighborhoods. The EPA gathered air samples for lab analysis, used meteorological equipment to track wind patterns, and deployed an infrared camera to detect volatile organic compounds.
The EPA’s findings were shared with the City Council in May 2025 and identified low levels of toluene, ranging from 58.8 to 425 parts per billion, as the likely source of the reported odors. According to the EPA, these concentrations are approximately 100 times lower than the threshold known to impact human health (20 parts per million).
Toluene has a strong, acetone-like smell that can be detected by people even in very low concentrations. Trace amounts of benzene were also detected, measured at less than 3 parts per billion, which is also more than 100 times below the minimum risk level for human exposure. While the EPA did not identify any adverse findings or violations, continued compliance monitoring of the Clean Air Act is expected to continue.
More information on the EPA’s findings can be found on our website.