EPA mobile monitoring detected toluene at low levels; EPA found facility in compliance, city staff say

City staff updated the commission on air‑quality testing conducted by the U.S. Environmental Protection Agency and the Iowa Department of Natural Resources after residents reported recurring odors in a neighborhood. Staff said the agencies deployed mobile sensors, drove sampling routes that included residential streets and a variety of times and did not preannounce the sampling schedule to avoid altering conditions.

According to the memo and the staff presentation, the EPA’s mobile sampling detected measurable levels of toluene — a volatile organic compound that can smell similar to acetone. Staff said EPA performed an unannounced follow‑up visit to the facility the sampling suggested as an emission source, reviewed documents and operations, and reported that the facility was operating within regulatory compliance. The staff presenter said the EPA did not recommend further enforcement action based on the sampling and follow‑up.

Staff emphasized the detection level reported in the memo was low in context and noted the difference between episodic detectable odors and concentrations that would require regulatory action. Staff also told commissioners that, in practical terms, a driver refueling a gasoline vehicle on a hot day will be exposed to higher concentrations of certain hydrocarbons than the levels detected in the EPA sampling, as a way to provide perspective on relative concentrations.

Commissioners asked whether the sampling had been compared to European exposure limits; staff said they had not done that comparison but could look into it. Staff said the EPA cited Center for Disease Control materials about toluene health effects in its report. Staff reiterated the purpose of the update was transparency and to inform the commission; no formal action or policy decision was requested of the commission in this agenda item.