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 monitors are taken offline for servicing.
- A blank graph indicates that the monitor is off-line for repair or has been disconnected because of consistently high levels of electrical interference at that location.
- Electrical interference can cause spikes, shown on graphs as one point significantly higher than the rest of the data.
- As you view data, be aware that there are often large differences in normal background radiation among the monitoring locations because background radiation levels depend on altitude and the amount of naturally occurring radioactive elements in the local soil. What is natural in one location is different from what is natural in another.
- To view the data shown in this graph, please use the query tool to search the RadNet database in EPA's Central Data Exchange.
- More information about air monitoring data.
Most naturally-occurring and manmade radionuclides emit either beta particles or gamma photons ("gamma rays"), and many emit both. Monitoring the air for beta and gamma radiation provides EPA scientists a picture of radiation in the environment, whether it is normal background radiation or increased levels from radiological incidents. We provide near-real-time gross gamma count rates in graphical form on this page. Gross beta count rates also are available.
Where can I find beta monitoring data?
- You can find reviewed and approved near-real-time beta air monitoring data, for this monitor, using the query tool to search the RadNet database in EPA's Central Data Exchange. There may be large gaps in these data. Near-real-time beta monitoring results frequently do not pass quality control criteria due to local radiofrequency interference. For this reason, near real-time beta monitoring graphs are not displayed on this site.
- Beta activity levels from laboratory analysis of air filters are available in Envirofacts.
- You can learn more about beta radiation from our Beta Particles fact sheet.
Conducting laboratory analysis on the filters from air monitors and on samples of precipitation, drinking water, and milk gives EPA scientists more information about which radionuclides are in the environment. Under normal conditions, RadNet sample analyses provide background levels of radiation in the environment. Over time, these routine data form a baseline that can help identify higher levels of radiation from radiological incidents.
Where can I find sample analysis/laboratory results?
- RadNet laboratory results from analysis of air monitor filters and samples of precipitation, drinking water, and milk are available two forms:
- Envirofacts includes RadNet data that is measured in the laboratory from air filters collected from each monitor, as well as current and historical radiation data on drinking water, milk, and precipitation.
- Environmental Radiation Data (ERD) is an electronic and print journal. It contains data from RadNet and its predecessor systems.