 Have you ever wondered what your family and your close friends are breathing? Seeing all the cars passing by and thinking, whoa, that surely must emit a lot of pollution. You can hardly see or smell air pollution, but it doesn't mean it's not there. Particulate matter, which is a type of air pollutant, can penetrate the deepest parts of our lungs and affect our health in many different ways. To measure its concentration in the air, we build low-cost air quality sensors that can be set up in any household. The stations set up by public organizations are very expensive. Our sensors aim at providing complementary measurements to the ones of those stations. Citizens coming together have the capacity to build a comprehensive sensor network. We hope to have at least 100 people building and adopting a sensor. This would be a huge step forward to understand how clean the air of our city is. You want to be part of this movement? Come to the workshop, build your own sensor and bring forward our understanding of air quality in Brussels.