Fukushima Radiation In Southern California: Hardly Detectable So Far

A March 21, 2011 Global Security Newswire article reports that only minimal amounts of radiation have been detected by the EPA as of last Friday.

The EPA RadNet system -- established to supply scientists with real-time notifications of heightened radiation levels -- had not found any "radiation levels of concern," the release states. Similarly, an Energy Department initiative has found no radiation levels that prompt concern. . . .

A radiation monitor in Sacramento, Calif., on Friday found trace amounts of iodine isotopes that measure "approximately 0.0002 disintegrations per second per cubic meter of air" and do not represent a threat to public health, according to the release.

Well, iodine (Iodine-131) was one of the radioactive elements of concern (Cesium-137 is another). But what does "0.0002 disintegrations per second per cubic meter of air mean? Well, a "disintegration" is the process by which the nucleus of the iodine changes to produce radiation. Radiation is not produced continuously; one particle of radiation is produced per disintegration.

So 0.0002 disintegrations per cubic meter of air means 1 disintegration per 5000 cubic meters of air. How much is 5000 cubic meters of air? Well, if you have a 2000 square foot house with 8-foot ceilings, you have about 16,000 cubic feet of volume, which converts to about 453 cubic meters of air. So the figure provided equals about one disintegration per about 11 houses worth of air, per second. It's a pretty low number of disintegrations, and a pretty low amount of radiation.

But wait--this was on Friday, the first day the radioactive particles were predicted to arrive. What about today? The EPA has radiation monitoring stations in California, including in Anaheim, Los Angeles, Riverside, and San Diego. According to this map, the monitoring station in San Diego is offline, but the stations in Anaheim, Los Angeles and Riverside are actively monitoring.

The Riverside monitoring station shows no evidence of an increase in radiation levels over the last three days:

Beta and gamma are two different types of radiation. According to the EPA website, the gamma radiation is broken up into different energy ranges to help determine which radioactive isotopes might be present. The word "gross" means "total," and "count rate" indicates relatively how much radiation is present; the higher the count rate, the more the radiation. What is important in looking at these charts is the average amount of radiation over several days; it appears to be approximately the same before and after March 18, the date when radiation was supposed to first reach California. There does not, yet, appear to be a trend of increasing radiation.

The Los Angeles charts tell a similar story:

Same with the Anaheim monitoring station:

The EPA cautions that:

As you view the 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.

Thus, it appears that Southern California, for now, is seeing no discernible increase in radiation due to the Fukushima nuclear facility disaster. We will monitor the situation ourselves over the next couple of weeks to see if things change.