Japanese Nuclear Emergency: Radiation Monitoring
About RadNet Laboratory Data
This site contains information and data from March 11, 2011 to June 30, 2011. EPA has returned to routine RadNet operations. This site will continue to be available for historical and informative purposes.
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Air Filter and Air Cartridge
The detailed filter analysis allows us to see the trace amounts of radioactive material that our sensitive near-real-time air monitors don't pick up. The filter analysis identifies the specific radioactive material and its amount.
The detailed filter and cartridge analysis presents air sampling data for detected radioactive material associated with nuclear power incidents. The results show the average concentration of radioactive material in the measurement: picocuries per cubic meter (pCi/m3) over the sampling period.
Results are presented from two types of air sampling: air cartridge and air filters.
- Air Cartridge Sampling: RadNet deployable monitors pass air through a cartridge that contains charcoal. The cartridges collect radioactive particles and gases in much the same way that a home charcoal air filter traps cooking odors. The cartridges are sent to an EPA laboratory for a sensitive laboratory analysis which can detect gaseous radioactive material in the sample. The date on the data table is the day that the canister was taken off the sampler.
- Air Filter Sampling: RadNet stationary or deployable monitors pass air through a filter which traps particulates. The filter is sent to an EPA laboratory for a sensitive laboratory analysis which can detect radionuclides present. The date on the data table is the day that the filter was taken off the sampler for analysis.
EPA scientists routinely test precipitation samples from more than 30 sites in the U.S. The stations submit precipitation samples to the EPA lab as rainfall, snow or sleet occurs. Under routine circumstances, samples are composited and analyzed by EPA scientists monthly. In response to the Japanese nuclear incident, gamma analyses were being performed on the precipitation samples as they're received.
It took up to five days for results because of the number of samples directed to the laboratory. This was to ensure the proper analysis and quality assurance measures took place before the results were released. EPA expected to see radioisotopes consistent with the Japanese nuclear incident during sample analysis. EPA expected the measured levels to be extremely low as this air mass disperses across our planet. All results are in picocuries per liter (pCi/L). A picocurie is one trillionth of a curie.
As part of our efforts to ensure that there is no public health concern in the U.S. related to radiation exposure, EPA routinely samples cow's milk at more than 30 stations every three months.
EPA has accelerated our quarterly milk sampling across the nation to collect the samples immediately. This action is precautionary, to make sure that we are gathering as much data as possible, informing our scientists and the public.
The milk samples are analyzed by gamma spectrometry, looking for fission products such as iodine-131 (I-131), barium-140 (Ba-140), and cesium-137 (Cs-137), which could become present in the event of a nuclear accident. All results are measured in picocuries per liter (pCi/L). A picocurie is one trillionth of a curie.
EPA's RadNet Drinking Water Program obtains quarterly drinking water samples from more than 50 sites across the country. Due to the Japanese nuclear incident, our sampling stations nationwide collected samples immediately and sent them to our laboratory for analysis.
It took about a week for results, because of the number of samples being directed to the laboratory and to ensure the proper analysis and quality assurance measures take place before the results are released. All results are measured in picocuries per liter (pCi/L). A picocurie is one trillionth of a curie. It's important to remember that radioactive material from Japan will have to travel thousands of miles through the air before reaching the U.S. The material will be widely dispersed and diluted by wind. To impact drinking water, the material would need to be caught in precipitation, fall to the ground and eventually enter drinking water.