Eau de Cité - Pacific Standard

Eau de Cité

Mapping the smells of a city may help governments plan better, richer cities, researchers argue.
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(Photo: Hobvias Sudoneighm/Flickr)

(Photo: Hobvias Sudoneighm/Flickr)

These days, you can find a map of just about anything: streetstrafficsports teams, even accents. One thing you can't map: smells.

Until now.

Artist and designer Kate McLean, together with computer scientists Daniele Quercia, Rossano Schifanella, and Luca Maria Aiello, has created a guide to urban odors. The most intriguing aspect of this research might be how they accomplished this unusual task of smell-mapping: geographically tagged social media.

McLean first started mapping smells around 2010, while she was roaming the streets of Edinburgh and Paris. All the while, McLean took notes on the odors and aromas she encountered, much as an oenophile might record the tastes of various wines. That evolved into a series of "smellwalks," some on her own and some collaborative, conducted in cities and neighborhoods around Europe and the United States.

The smell of garbage was most concentrated in areas with the most bars, while cleaning product and other chemical odors proliferated around industrial areas, transportation hubs, and hospitals.

The point of these smellwalks, McLean explains, is to highlight the fact that most of the discussion and design of urban areas focuses on visual aspects. That's a shame, she says, because smell is equally important in how we experience a place—something that could have real consequences for city planners. Getting people to take advantage of a new park, for example, isn't just about the views, the playgrounds, or the quality of the grass; it's about the total experience, which depends in part on smell.

While smellwalks are informative, they're time intensive and not particularly scalable—not exactly ideal caveats for a government program. That's where the computer scientists, who figured social media might be able to help, came into play. They began by compiling a "smell dictionary" based in part on specific words people said during McLean's walks. Then, they searched for those words in 17 million public Flickr photo tags, 1.7 million tweets, and 436,000 Instagram photo captions that had been geotagged somewhere within London or Barcelona.

Overall, the team found, Barcelona's smells were mostly those of food and nature, while London's were dominated by traffic emissions—already something London planners might want to know. Smells varied between neighborhoods as well. For example, the smell of garbage was most concentrated in areas with the most bars, such as Blackfriars, London, while cleaning product and other chemical odors proliferated around industrial areas, transportation hubs, and hospitals.

Most importantly, those smells could give decision-makers key information that's difficult or costly to acquire. For instance, odors associated with traffic were closely correlated with poor air quality, while the opposite was true for smells associated with nature.

"We hope to empower designers, researchers, city managers by offering them a number of methodological tools and practical insights to re-think the role of smell in their work," the team writes. They presented their research last week at the 2015 International AAAI Conference on Web and Social Media.

Quick Studies is an award-winning series that sheds light on new research and discoveries that change the way we look at the world.

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