Hollandse Luchten sensor kit
Hollandse Luchten is a citizen science project in which a citizen-driven measurement network is being set up in North Holland. Citizens measure air quality themselves with the use of open source hardware and can view their data live on the online platform of Hollandse Luchten. In addition, various experts in air quality are involved to calibrate the data and to ensure they are as reliable as possible.
HoLu sensor kit
Waag has developed a modular sensor kit for measuring outdoor air quality. The HoLu sensor kit is available in two variants: Basic HoLu kit and Extended HoLu kit. The Basic measures particulate matter and the Extended also has two gas sensors for Nitrogen Dioxide and Ozone.
Check out the HoLu sensor (in Dutch)