Beta particles and gamma rays may come from natural sources that are part of our environment, or they may come from man-made sources, such as nuclear fuel. Tracking beta and gamma radiation helps us determine the type and amount of the radioactive material in the air. By looking at the data over time, scientists recognize what is "normal" or "background" radiation in a particular location. Any reading above normal will trigger an alert to EPA scientists to review the data. If a high reading is determined to have been caused by instrument error or local radiofrequency interference, scientists remove the data point from the database.
During a radiological incident, RadNet data can be used to help decision-makers decide whether protective actions need to be taken to safeguard the public. You can read more about RadNet data and its uses in the publication, Historical Uses of RadNet Data (PDF) (36 pp, 564.16 K, About PDF).