Answer to Question #12007 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
Is a handheld detector like the Medcom Inspector sensitive enough to detect an increase in background radiation due to a nuclear accident (similar to Fukushima) from 1,600 kilometers (km) away?
Even though the Fukushima event was very severe, and radiation levels close to the accident scene were very high, radiation levels dropped off very rapidly with distance. At 1,600 km away, there would be little likelihood that we would be able to detect the direct radiation from the reactor with the instrument you have.
However, there was also radioactivity released to the air during the Fukushima event, and even at large distances downwind, scientists were able to detect some radioactivity. This was done by operating air-sampling devices that filter dust and particulates out of the air. A detector is then placed over the filter to look for accident residue.
Using this method, you may be able to detect radioactivity above background at some distance from the accident. Note that there is natural radioactivity in the air that will show up on the filter. However, that is reduced by radioactive decay after several hours, leaving mostly accident residue.
Joel Cehn, CHP