By designing small birdhouses equipped with sensors to detect the level of pollution in the air, TreeWiFi serves as a visual marker of just how dirty or clean the environment is at a given time. Most importantly, it offers a concrete incentive for residents to remedy poor air quality. When the air quality improves, the birdhouse lights up in green and unlocks complementary wi-fi access. If the air stays polluted, the lights remain red, indicating that wi-fi is not available.