State environmental officials can't explain why residents of one western Pennsylvania city thought part of their town smelled like cat urine last year.
The New Castle News reports a state Department of Environmental Protection report was inconclusive.
The DEP says it's likely that some kind of waste containing mesityl oxide mixed with some kind of sulfur compound to create the smell. But air samples and testing of substances at the city's sewage treatment plant didn't turn up a source of the substances.
Mesityl oxide is used in paint removers, as a solvent and, sometimes, in insect repellents.
The city, which is is about 45 miles northwest of Pittsburgh, first contacted the DEP in October 2014.