New Paper: Mapping the Invisible-Decoding Perceived Urban Smells through Geosocial Media in New York City

Urban analytics still tends to privilege what can be seen. Smell, by contrast, is harder to capture: it is fleeting, context-dependent, and often described indirectly through memory, association, or complaint. This mismatch motivated our paper, “Mapping the Invisible: Decoding Perceived Urban Smells Through Geosocial Media in New York City,” written with Ate Poorthuis and Andrew Crooks, and published in Annals of the American Association of Geographers.

The theoretical starting point is that smell is not simply an environmental stimulus. It is an emplaced and relational experience, tied to memory, emotion, activity, and the social meaning of urban space. This makes smellscapes difficult to capture through conventional spatial data alone. People also rarely name smells directly; the “tip of the nose” problem means that smells are often expressed through associations, objects, situations, and place-based encounters. We use geosocial media to operationalize this difficulty: tweets provide situated traces of how people name, imply, and locate smells in everyday language, allowing us to examine the spatialities of perceived urban smells at a city-wide scale.

Using New York City as a case study, we analyzed more than 56 million geotagged tweets from over 3.2 million users. We derived both explicit smell references, such as direct mentions of something smelling bad, and implicit references, where smell is inferred through associated objects or situations. This bottom-up approach allows smell categories such as food, nature, waste, transportation, smoke, and alcohol to be mapped and compared across neighborhoods.

In short, the paper makes a cautious argument for using geosocial media in smellscape research. The value lies not in treating social media as a complete record of urban smell, but in using it to reveal sensory traces that conventional visual or mobility data would often leave out.

Abstract:

Smells can shape people’s perceptions of urban spaces, influencing how individuals relate themselves to the environment both physically and emotionally. Although the urban environment has long been conceived as a multisensory experience, research has mainly focused on the visual dimension, leaving smell largely understudied. This article aims to construct a flexible and efficient bottom-up framework for capturing and classifying perceived urban smells from individuals based on geosocial media data, thus, increasing our understanding of this relatively neglected sensory dimension in urban studies. We take New York City as a case study and decode perceived smells by teasing out specific smell-related indicator words through text mining techniques from a historical set of geosocial media data (i.e., Twitter/X). The data set consists of more than 56 million data points sent by more than 3.2 million users. The results demonstrate that this approach, which combines quantitative analysis with qualitative insights, can not only reveal “hidden” places with clear spatial smell patterns, but also capture elusive smells that might otherwise be overlooked. By making perceived smells measurable and visible, we can gain a more nuanced understanding of smellscapes and people’s sensory experiences within the urban environment. Overall, we hope our study opens up new possibilities for understanding urban spaces through an olfactory lens and, more broadly, multisensory urban experience research.

Full reference:

Chen, Q., Poorthuis, A., and Crooks, A. T. (2025). Mapping the Invisible: Decoding Perceived Urban Smells Through Geosocial Media in New York City. Annals of the American Association of Geographers, 1-21. https://doi.org/10.1080/24694452.2025.2485233

Read more: Project page · Publication page · https://doi.org/10.1080/24694452.2025.2485233