Enhancing national environmental monitoring through local citizen science

Highlights: • Citizens are highly motivated to contribute to air quality measure- ments that complement existing measurement networks because of their high spatio-temporal resolution; • Data needs to be assimilated, for example, using models; • Low-cost sensors need to be developed further, and their applica- tion calibrated and validated; • Easily accessible expert information and feedback is needed to sup- port participants; • Environment protection agencies (EPAs) can both support and benefit from citizen science using small sensor networks.