This is a document that offers a methodology to obtain maps of air pollution (including ultrafine particles) using mobile monitoring and citizen observatories to assess air quuality policies and to improve evaluation of health effects of long-term. More specifically this document summarises complementary approaches to traditional air quality monitoring networks in order to assess air pollution exposure for health and epidemiological studies, and to assess policy actions at urban scale. This proposes a methodology, including involving citizens and mechanisms to enrol citizens that can be readily upscaled at European levels.