Residents in Madrid have been experiencing unhealthy levels of air and noise pollution for many years now. During 2018 the City Council of Madrid deployed an ambitious plan including new measures in order to reduce air and noise contamination and improve liveability across the city. “Madrid Central” was launched as a specific action towards traffic restrictions and air quality improvement. This plan covers an area of the city centre that comprises 480 hectares and aims to reduce the current emissions of nitrogen dioxide (NO2) by 40%. The intervention applies traffic restrictions to favour pedestrians, bicycles and public transport. Additionally, speed restrictions (max. 70 km/h) have been applied to different ring roads (M30 and M40) and to a section of the A5 highway (max. 50 km/h). While the City Council is trying to measure the impact of these policies, there are very few measuring devices set in place to enable the correlation of traffic counting, air quality and speed limit compliance at the required level of granularity. This gap leaves ample room for citizens to contribute more detailed air quality and traffic data to assess the impact of these policies. In this regard, the WeCount pilot in Madrid aims to give citizens a central role in assessing the effects and compliance with this new public policy, by measuring and correlating air pollution and traffic data leveraging citizen science and Telraam traffic counting devices, while reaching an unprecedented level of granularity. Different community groups of residents living both inside and around the Madrid Central area and around the A5 highway entrance will participate in this pilot. Participants will not only have an opportunity to contribute to traffic issues in an informed way, but will also develop: skills and capacity to deploy digital sensors and make sense of data; social bonds and community around a shared matter of concern, thus developing a community of practice to provoke bottom-up environmental and policy actions.