Air pollution is very difficult to measure. Apart from the expensive, professional equipment, more and more inexpensive alternatives become available. Because of the many scattered initiatives, information about the usefulness of these low-cost sensors is often difficult to find.
Snuffle.org is an initiative of KNMI as part of the EDUCEO project funded by ESA. Since 2015, this site contained a public knowledge base bringing together all the available information about sensors (i.e. the components sensitive to air pollution) and sensor boxes (i.e. practical devices containing sensors). However, the project has ended, and as developments go rapidly in this field, the information of the wiki was considered outdated and taken offline.
If you have specific questions considering low-cost sensors, setting up low-cost sensor campaigns, calibration issues, or assimilation of measurement data in air quality models, please don't hesitate to contact Bas Mijling. Otherwise, try your luck at one of the pages listed below: