For nearly three weeks, the Illinois Environmental Protection Agency has been investigating widespread reports of a mysterious chemical odor across the Chicago area—a smell variously described by residents as “burning plastic,” “an old microwave,” and “what I imagine the inside of a USB cable smells like.” Complaints have come in from across the city, the suburbs, and as far away as central Illinois and southern Wisconsin, with no definitive source identified.

Until now. Sort of.

On Monday, a Chicago-based startup called AuraSync Studios issued a press release claiming full responsibility for the smell, which it described not as a chemical leak or industrial accident, but as “the Midwest’s first large-scale ambient brand activation experience.”

“What people are smelling is not a malfunction. It’s a feature,” said AuraSync CEO and co-founder Petra Lindström during a hastily arranged press conference at the company’s Fulton Market headquarters, which did, reporters noted, smell faintly of burnt plastic. “We’ve developed a proprietary atmospheric scent-dispersal technology that allows brands to reach consumers through the most underutilized marketing channel: the air itself.”

According to AuraSync’s investor deck—which a Dispatch reporter obtained and which contains the phrase “disrupting the olfactory space” eleven times—the company has raised $8.2 million in seed funding to develop what it calls “ScentReach,” a platform that uses high-altitude scent dispersal units to release branded fragrances across metropolitan areas. The technology, the deck claims, can “deliver a brand’s essence directly into consumers’ nasal passages at scale.”

The Illinois EPA was not immediately available to confirm or deny AuraSync’s claim. A spokesperson said the agency is “continuing its investigation into the source of the odor” and is “not currently in a position to attribute it to any specific entity, startup or otherwise.” The spokesperson added, after a pause, “We were not aware this was a category of company that existed.”

AuraSync says the smell that blanketed the region was a “test deployment” of a scent called “Urban Momentum,” which it describes in marketing materials as “a bold, industrial-forward fragrance that evokes progress, ambition, and the unstoppable energy of American innovation.” Multiple residents who smelled it described it as “a tire fire at a nail salon.”

The startup’s claims have been met with a mixture of skepticism and alarm. Dr. Rebecca Torres, an atmospheric chemist at Northwestern University, said that while she cannot rule out AuraSync’s involvement, the technology described in the company’s materials “does not correspond to any known method of large-scale scent dispersal.” She added: “You can’t just make Wisconsin smell like something. That’s not how air works.”

Industry analysts have been equally dubious. “The marketing-to-technology ratio in this company is approximately forty to one,” said Priya Anand, a venture capital analyst at Morningstar who reviewed the investor deck at the Dispatch’s request. “They have a very detailed go-to-market strategy and, as far as I can tell, no actual product. Which, to be fair, has not historically stopped companies from raising money.”

AuraSync says it is in talks with “several major consumer brands” for future scent activations and expects to be “cash-flow positive by Q3 2027.” Lindström declined to name any brand partners but said one upcoming campaign would involve “a much more pleasant smell” and would be “specifically targeted to the greater Chicagoland area, with minimal Wisconsin bleed.”

The Illinois EPA says it expects to release preliminary findings from its ongoing investigation within the next two weeks. In the meantime, AuraSync’s website invites interested brands to “book a nasal impression” through its online portal, which, as of press time, appeared to be a Google Form.