Frequent Questions: Air Filter Testing
View frequently asked questions about the RadNet air filter testing.
On this page:
- How does the EPA analyze air filters?
- Where can I find results for beta monitoring in air?
- How does the EPA measure radiation if the air monitor in my area is not operating?
- Why does the EPA test air filters for radionuclides?
How does the EPA analyze air filters?
RadNet operators ship air filters from the monitoring location to the EPA’s National Analytical Radiation Environmental Laboratory (NAREL) for analysis. RadNet sample analysis on air filters is conducted following a routine schedule, unless analysis is accelerated after an emergency event.
All air filters go through an initial screening for beta radiation, followed by a screening for gamma radiation scan if the beta activity is greater than 1 pCi/m3. For each air filter, laboratory analysis provides the average concentration of a contaminant over the sample collection period in picocuries per cubic meter (pCi/m3).
Each year, a composite sample of the air filters for each monitor is analyzed for gamma-emitting radionuclides. Isotopic plutonium (Pu-238, Pu-239/Pu-240) and uranium (U-234, U-235, and U-238) analyses are performed on composite samples from one-fourth of the stations on a four-year rotating schedule. View air filter analysis results for each RadNet air monitoring location on its individual webpage on the RadNet website.
Where can I find results for beta monitoring in air?
The EPA monitors beta particles as part of the RadNet network through routine laboratory air filter analysis. RadNet air filters are sent to the EPA’s National Analytical Radiation Environmental Laboratory (NAREL) for measurement of gross beta air concentrations and further analysis if warranted. Analysis results for beta measurements on air filters are available on RadNet individual monitoring location webpages or through the Envirofacts website.
In the past, the EPA presented near-real-time monitoring data for gross beta counts. The EPA discontinued the near-real-time gross beta monitoring program because the detectors were neither able to confirm nor rule out the presence of specific beta emitters. The beta detectors were unable to provide identification or quantification of specific nuclides, and the beta detectors were subject to various interferences.
How does the EPA measure radiation if the air monitor in my area is not operating?
The EPA placed 140 monitors across the country to provide overlapping coverage with wide-area, nationwide monitoring in mind. If a monitor is not operational in one area, or is being repaired, the EPA's network will still be able to detect any regional fluctuation in background levels of radiation because of extensive coverage across the United States.
Why does the EPA test air filters for radionuclides?
The RadNet system provides continuous, near-real-time measurements of radiation levels across the country during normal and emergency conditions, and it is the only national radiation monitoring system in the United States. RadNet's laboratory analyses provide greater analytical sensitivity and have the capability to measure the samples using a wide range of analytical techniques that can be selected as indicated by a specific radiological event. Through routine air monitoring and air filter analysis, the EPA is able to establish normal background levels of radioactivity and detect additional activity from man-made radioactive sources.