A Smell Test for Graffiti

The age-old cat-and-mouse game between police and graffiti artists has gotten a lot more interesting lately, with the advent of new technologies. Earlier this month, CityLab reported on the use of drones in public art and vandalism—most notably, in tagging a prominent Calvin Klein billboard in New York. But artists aren’t the only ones with tech on their side: now Sydney’s rail authority is deploying a next-generation anti-graffiti system to catch vandals in the act.

The tool, aptly named Mousetrap, uses electronic chemical sensors to detect vapors of permanent markers and spray paint in real time. As soon as Mousetrap sniffs out a tagging in progress, it alerts transit staff monitoring CCTV feeds of Sydney rail stations. Then transit police can arrest the vandals.