Nikolas Bentel, a designer in New York City, has released a range of shirts that change colour in the presence of pollution, according to Mark Fihn’s Flexible Substrate. Bentel worked with Autodesk to develop three different shirts: one that detects carbon monoxide, one that detects particle pollution (like excessive dust) and one that detects radioactivity. All three work in different ways. For example, parts of the first shirt are embedded with chemical salts; these lose an oxygen molecule when in contact with carbon dioxide, and turn black. The particle shirt uses two sensors, which communicate with a micro controller in the collar when they detect particles. The controller signals patches in the shirt placed behind heat-activated dots and warms them, causing the dots to turn black.