CAROLINA aims to explore a new dimension of an urban air pollution monitoring and re-shape urban mobility based on minimizing the number of people exposed to the threshold values of harmful air pollution in European cities. The other unique value proposition is to involve citizen as part of the collaborative urban air pollution monitoring system, based on the statement that users are producers, not only consumers, and it is expected to provide the opportunity to engage citizens in the decision-making process of urban air quality in European cities.