AirTick is a project from Pan Xheng Xiang at the Nanyang Technological University in Singapore, that uses crowdsourced photos to analyse how hazy the environment looks. The app then combines this data with official air quality data using machine-learning to develop a method for predicting pollution levels based on the images alone. Here’s the project’s entry for the AirTick – Singapore Challenge 2016.
More from CityLab: Donating Your Selfies to Science. The article also describes many more applications using crowdsourced photos (e.g., for traffic safety problems, etc.).