Monitoring Results from Chicago, IL RadNet gamma detectors
measure radiation from all radionuclides in the air that emit
gamma rays. On this page: The graph below shows the gross gamma
count rate data from the air monitor at this location. By
reviewing and comparing gamma count rates over time, EPA can
tell if changes in the data are caused by the normal
fluctuations in background radiation from naturally occurring
sources or if they represent new radiation from a man-made
source. Not all gamma rays have the same amount of energy.
Breaking the data into energy ranges helps scientists determine
which radionuclides are present. Near-Real-Time Gross Gamma
Count Rate Data Notes on the Graph - Gross, or total, means the
measurement is from all gamma emitting radionuclides. - Count
rate tells us how quickly gamma rays are being detected, which
indicates how much radioactivity the monitor is seeing. - Brief
gaps in RadNet data represent instrument error. - Larger gaps
(>1 day) occasionally appear when RadNet monitor