Researchers create maps of what cities smell like
London stinks of traffic pollution and waste while Barcelona smells like food and nature. Anyone's who been to either city could well have told you that, but now it's been proven by science.
A group of researchers are mapping cities by their smells.
Volunteers go into the field, follow their noses and record what they smell.
These smell notes are matched up with social media data to produce "smelly maps" of cities.
This map shows which parts of London smell like nature (green) and which parts smell like traffic pollution (red).
The busier roads stink of emissions, and the parks smell like nature.
The data correlates with air quality maps.
Here's a map of the areas of London that smell like animals.
The hot spot in the north is London Zoo.
Much like a perfume, the researchers say each city has base notes, mid-level notes and high-notes.
Residents of cities become relatively immune to base-level notes, noticing only mid-level smells, like fish markets or factories, and high-level smells like goods from a leather shop.
Here's a map of Barcelona showing emission smells and nature smells.
It's much the same pattern as London, high-traffic streets in red, high nature areas in green.
And here's how the two cities compare.
It's not shown on a map but the research team found they could track mid-level smells using a combination of their smell walks and social media data.
Food smells are found near food markets (Boqueria market in Barcelona, and the Borough Market in London) and in areas where restaurants cluster (Born and Barceloneta in Barcelona).
Smells of waste and smoking are found in areas that enjoy the evening economy (Barceloneta and Bogatell beach in Barcelona and Blackfriars and Elephant and Castle in London).
And big industrial areas, such as hospitals and big railway stations smell like cleaning products and chemicals.
The team, consisting of Daniele Quercia, of the University of Cambridge, Rossano Schifanella, of the University of Torino, Luca Maria Aiello, of Yahoo Labs, and Kate McLean of the Royal College of Art & CCCU, have produced smell-walk data in Amsterdam, Pamplona, Glasgow, Edinburgh, Newport, Paris and New York.
Their research paper is available here.