A large scale public health/public safety initiative when I worked for the City of New York was NYPD’s radiation monitoring program. Designed to detect a dirty bomb, it makes use of wireless real-time alerting.
Now you can perform your own monitoring as part of your amateur radio station and send the results in real-time to the Automatic Packet Reporting System.
Amateur radio operator “Adminck” (S55MA) in Slovenia has published this blog post. It explains how a Raspberry Pi Zero, a tiny geiger counter, and some scripts are sending his radiation measurements live to the world via the internet.
You can see the actual reports here.