Frequent Questions: Precipitation Testing
View frequently asked questions about the RadNet precipitation testing.
On this page:
- Why does the EPA test precipitation for radionuclides?
- How does the EPA sample precipitation for radionuclides?
- How does precipitation affect radiation levels in the environment?
- What federal, state, or local standards exist that address radiation in precipitation?
- Where can I find the analytical results from precipitation samples?
Why does the EPA test precipitation for radionuclides?
By monitoring precipitation on a regular basis, the EPA is able to establish normal background levels of radioactivity and detect activity from man-made radioactive sources. Analyzing precipitation samples along with air filters helps determine the amount and type of radioactive material present.
For more information about precipitation sampling analysis and results, visit Envirofacts.
How does the EPA sample precipitation for radionuclides?
Samples of precipitation such as rain, snow or sleet are collected at more than 25 stations across the U.S. Samples are collected using specially designed precipitation collection devices which funnel the precipitation into a bucket for transfer to a shipping container. EPA’s National Analytical Radiation Environmental Laboratory (NAREL) receives the sample. Under routine circumstances, the EPA scientists composite the individual samples into one container each month and perform gamma analysis on the composite samples. The results are posted to the RadNet Envirofacts database.
How does precipitation affect radiation levels in the environment?
It is very common for natural background radiation levels to change during precipitation events such as rain, sleet or snow. While there are many more factors that affect radiation levels than just precipitation, radon and radon decay products, which occur naturally may be captured in the precipitation and brought to the ground, causing a temporary increase in radiation levels. However, barometric pressure and the vertical temperature profile, which determine the “lid” under which the radon is generally trapped, may negate the precipitation effect on radiation. Therefore, it is also possible that radiation levels won’t rise during a precipitation event. Snow and sleet may cause radiation levels to decrease since their buildup on the ground may shield radon migration into the atmosphere, as well as shield direct radiation from the ground.
For more information about precipitation sampling analysis and results, visit Envirofacts.
What federal, state, or local standards exist that address radiation in precipitation?
There are no EPA standards for radionuclides in precipitation. RadNet precipitation sampling results help establish trends and serve as a reference during radiological incidents. Scientists can use the information to predict wet deposition concentrations during an emergency and can also use the data to validate atmospheric dispersion model output.
For more information about precipitation sampling analysis and results, visit Envirofacts.
Where can I find the analytical results from precipitation samples?
All RadNet precipitation sampling results are available on the RadNet Envirofacts website.