Foul or musty? German city of Ulm seeks volunteers to sniff out mystery odours

The German city of Ulm is embarking on an unusual but intriguing experiment: to crack the case of recurring, so‑far‑untraceable odours drifting through its streets – using residents’ noses.

The State Agency for the Environment Baden‑Württemberg (LUBW) has launched a year‑long project inviting locals to report strange smells via a smartphone app, Ortelium.

Experts hope the technology will be able to detect patterns where human memory and municipal guesswork have so far fallen short.

The app links each smell report with meteorological data, allowing researchers to track how odour‑laden air pockets drift through the city.

Why Ulm?

Ulm – birthplace of Albert Einstein – may be picturesque, with its soaring Minster tower and riverside setting, but it's also a city where odour complaints crop up with surprising regularity.

As a LUBW spokesperson explained, “in recent years, the city has repeatedly received odour complaints, some of which could not be traced to a specific source”.

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From the agency’s perspective, this makes Ulm an ideal testing ground for a new approach to odour management.

As part of the project, volunteers are being asked to log any noticeable smell, whether pleasant or unpleasant, whose origin they cannot identify over the course of the year.

To help them recognise what they should be recording, participants are initially given a ‘scent stick’ and asked to assign it to a category – reportedly including “musty”, “foul” and “like cat urine”.

Scientists hope that combining these reports with weather data will shed light on how far odours travel and help narrow down potential sources. They will also assess how well the app performs in real‑world conditions.

The investigation is being carried out by LUBW in partnership with the Ulm city authorities and is funded by Baden‑Württemberg’s Ministry of the Environment.

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What happens at the end of the experiment will depend on the results. If successful, the model could be expanded across the state – and Ulm may finally gain some clarity on what’s been causing headaches and waking some residents at five in the morning, according to reports in SWR Aktuell.

How to Get Involved

If you live in Ulm or the surrounding area and want to take part, you can still sign up to become an official “odour reporter”. Registration is open via the city’s administration, and participants receive regular updates every one to two months on the project’s progress.

More details for anyone interested in taking part can be found here.