The Three Mile Island Citizens' Monitoring Network (TMI-CMN) is a local, grassroots organization that monitors radiation in a 15-mile radius around the TMI nuclear facility. During the 1979 accident at the Three Mile Island power plant, it was impossible for people in the area to get reliable measurements of the current radiation levels. Our purpose is to provide accurate information about radiation levels to the public and appropriate organizations and government agencies.

The TMI-CMN monitoring system uses state-of-the-art technology to collect data at 30 remote stations and send it by radio to a central station, where it is displayed on a map in near-real-time and saved for analysis. The Harrisburg Emergency Communications Center has an adjunct central station and always has access to the current data. You can see the same map. We also send monthly reports to several federal, state, and local agencies.