California Radiation Levels
30 CPM: Normal. listen
23 August 2013, 9:57 AM PST (1657 UTC)
When I was unable to find any published real-time data for California radiation levels, I decided to buy my own Geiger Counter and take my own readings. Once I had this data, I realized that everyone else in California was curious, too, so I publish the levels here. I've wanted a Geiger counter for years, so the Japanese nuclear meltdowns of March, 2011, was the perfect excuse. (Unlike us Americans, the Japanese have live data for their entire country readily available in a legible format.)
Since I've left La Jolla for a life on the open seas, my former La Jolla neighbor is taking these readings for us. I'm publishing this site from international waters in the Pacific Ocean, 250 miles away from shore.
Measured Levels top
Location: Measured outdoors near La Jolla (San Diego), California, at 32º 53' N, 117º 13' W.
CPM is Clicks Per Minute on my SPER Scientific 840007 Radiation Detector. I measure for one minute and count the clicks. Every kind of detector records more or less clicks under the same radiation, so CPM is great for a relative measurement like these, but not suitable to compare readings between different radiation detectors. Comparisons between meters is done in µSv/hr, but these levels are so low that they don't even move the meter needle enough to read in µSv/hr.
Likewise, these clicks are completely random as you can hear by clicking the levels, and therefore, measured one minute to the next it will vary from 16-24 CPM. THese variations are just random variation, not real changes in the radiation levels. If I measured for ten minutes at a time I'd get more stable readings, but I'm not having my PhD friend stand outside counting for ten minutes every day. If the CPM suddenly rose to 100, we'd have something, but that still would be safe.
23 August 2013 , 9:57 AM PDT (1657 UTC): 30 CPM. Conditions: 22º C (70º F), bright, sunny and a bit humid.
30 January 2013 , 9:43 AM PDT (1743 UTC): 28 CPM. Conditions: 15º C (59º F), bright and sunny.
03 October 2012, 11:07 AM PDT (1807 UTC): 26 CPM. Conditions: 25º C (73º F), humid and partly foggy day.
15 July 2012, 9:11 AM PDT (1611 UTC): 26 CPM. Conditions: 19º C (66º F), nice, sunny cool morning.
02 February 2012 , 7:52 AM PDT (1552 UTC): 20 CPM. Conditions: 5º C (41º F), a brilliant clean and clear morning. The local nuclear plant, SONGS, had a leak at 3PM PST 31 Jan 2012, and nothing is different as measured.
01 November 2011, 7:39 PM PDT (0239 UTC next day): 24 CPM. Conditions: 16º C (60º F), dark.
05 July 2011, 10:46 AM PDT (1746 UTC): 18 CPM. Conditions: 24º C (76º F), sunny and muggy.
01 June 2011, 7:12 AM PDT (1412 UTC): 21 CPM. Conditions: 10º C (49º F), brilliant cool dawn with chirping birds.
25 May 2011, 6:45 AM PDT (1345 UTC): 17 CPM. Conditions: 10º C (50º F), sun rising with chirping birds.
15 May 2011, 9:42 AM PDT (1642 UTC): 18 CPM. Conditions: 15º C (59º F), overcast.
09 May 2011, 6:54 AM PDT (1354 UTC): 19 CPM. Conditions: 14ºC (57ºF), mostly overcast and a little blustery.
06 May 2011, 8:17 AM PDT (1517 UTC): 18 CPM. Conditions: 15ºC (58ºF), overcast.
04 May 2011, 7:08 AM PDT (1408 UTC): 19 CPM. Conditions: 15ºC (59ºF), brilliant dawn with happy springtime birds chirping.
02 May 2011, 6:49 AM PDT (1349 UTC): 16 CPM. Conditions: 10ºC (49ºF), a breezy, brilliant dawn with happy springtime birds chirping.
27 April 2011, 7:55 AM PDT (1455 UTC): 23 CPM. Conditions: 14ºC (57ºF), a brilliant dawn with happy springtime birds chirping.
26 April 2011, 6:51 AM PDT (1351 UTC): 24 CPM. Conditions: 15ºC (59ºF), a brilliant dawn with happy springtime baby birds chirping.
25 April 2011, 8:22 AM PDT (1522 UTC): 24 CPM. Conditions: 15ºC (59ºF), mostly sunny with happy chirping birds.
24 April 2011, Easter Sunday, 7:20 AM PDT (1420 UTC): 23 CPM. Conditions: 13ºC (56ºF), mostly cloudy, chirping birds.
20 April 2011, 7:27 AM PDT (1427 UTC): 25 CPM. Conditions: 16ºC (60ºF), mostly cloudy, chirping birds.
19 April 2011, 1:45 PM PDT (2045 UTC): 21 CPM. Conditions: 20ºC (68ºF), mostly cloudy.
13 April 2011, 10:49 AM PDT (1749 UTC): 20 CPM. Conditions: 15ºC (59ºF), partly cloudy.
12 April 2011, 8:45 AM PDT (1545 UTC): 13 CPM. Conditions: Springtime!
11 April 2011, 8:18 AM PDT (1518 UTC): 19 CPM. Conditions: 10ºC (50ºF), bright, cool and beautiful.
08 April 2011, 6:50 AM PDT (1350 UTC): 20 CPM. Conditions: 10ºC (49ºF), damp and mostly cloudy.
07 April 2011, 8:44 AM PDT (1544 UTC): 26 CPM. Conditions: 15ºC (59ºF), damp and overcast.
06 April 2011, 8:43 AM PDT (1543 UTC): 21 CPM. Conditions: 15ºC (59ºF), drizzle.
05 April 2011, 11:47 AM PDT (1847 UTC): 23 CPM. Conditions: 17ºC (63ºF), mostly cloudy.
02 April 2011, 8:02 AM PDT (1502 UTC): 15 CPM. Conditions: 13ºC (55ºF), a brilliant dawn as the birds chirp very happily.
01 April 2011, 8:13 AM PDT (1513 UTC): 16 CPM. Conditions: 13ºC (55ºF), a brilliant dawn as the birds chirp very happily.
31 March 2011, 7:02 AM PDT (1403 UTC): 30 CPM. Conditions: 10ºC (50ºF), dawn breaks over paradise as the birds chirp happily.
30 March 2011, 9:35 AM PDT (1635 UTC): 20 CPM. Conditions: 17ºC (63ºF), mostly sunny. Another day in paradise.
29 March 2011, 11:50 AM PDT (1853 UTC): 18 CPM. Conditions: 17ºC (63ºF), mostly sunny. Another day in paradise.
28 March 2011, 7:47 AM PDT (1447 UTC): 21 CPM. Conditions: 12ºC (54ºF), mostly cloudy with happy chirping birds.
27 March 2011, 7:52 AM PDT (1452 UTC): 20 CPM. Conditions: 12ºC (54ºF), overcast, with sort of wet roads from morning rain.
25 March 2011, 9:40 AM PDT (1640 UTC): 24 CPM. Conditions: 12ºC (55ºF) with steady light rain.
24 March 2011, 9:25 AM PDT (1625 UTC): 14 CPM. Conditions: cool and beautiful with brilliant sunshine and happy birds.
23 March 2011, 10:38 AM PDT (1738 UTC): 24 CPM. Conditions: cool and beautiful with brilliant sunshine.
22 March 2011, 9:44 AM PDT (1644 UTC): 23 CPM. Conditions: cool (52ºF/11ºC) and beautiful with brilliant sunshine and chirping birds.
21 March 2011, 8:02 AM PDT (1502 UTC): 21 CPM. Conditions: mostly cloudy and very wet from strong overnight rain.
20 March 2011, 3:38 PM PDT (2238 UTC): 20 CPM. Conditions: overcast and windy.
19 March 2011, 8 AM PDT (1500 UTC): 18 CPM. Conditions: lovely.
19 March 2011, 7 AM PDT (1400 UTC): 24 CPM. Conditions: lovely spring morning. You can hear the happy birds chirping springtime songs.
18 March 2011, 3:15 PM PDT (2215 UTC): 20 CPM. (no audio)
Radiation Units top
Units and Conversion Factors
20 CPM is about 0.06 μSv/hr on my meter (1 μSv/hr is 330 CPM on the SPER 840007).
μSv: microSievert (a millionth of a Sievert). Normal background radiation is about 0.3 μSv/hr, or about 2,600 μSv per year. MicroSieverts are negligible.
mSv: milliSievert (a thousandth of a Sievert). 1,000 μSv = 1 mSv. MilliSieverts are significant.
Sv: Sievert. Four or five Sv is a lethal dose. Sieverts are deadly.
REM (Röntgen Equivalent in Man). 1 REM = 10,000 μSv or 10 mSv or 0.01 Sv or 1/100 Sv. Background radiation is about 0.3 REM/year. Federal standard for all workers is 1 REM/year, and 5 REM/year for powerplant and nuclear medicine workers.
Dose versus Dose Rate
A dose is the total amount of radiation accumulated over some period of time.
Dose Rate is the rate at which radiation is accumulated.
Thus, if background radiation is 0.3 μSv/hr, the annual dose is 0.3 μSv/hr x 8,760 hours in a year = 2,600 μSv.
Therefore, when the NY Times showed a chart of the hourly radiation rates in Japan along with levels of typical annual background radiation in the same graphic, it made the usual layman's mistake of confusing dose rate with total dose. Since the dose rate is plotted per hour, and the annual background dose is for a year (8,760 hours), the NY times did us all a disservice by 1.) reducing the apparent severity of the Japanese radiation by a factor of 8,760, and 2.) simply clipped-off the deadly 400,000 μSv (400 mSv) readings where they ran off the scale.
Think of your pay. You may get paid $10/hr, and after working 2,000 hours in a year, your annual salary adds up to $20,000. Thus, the NY Times and others are looking at the hourly rates of radiation in Japan, and comparing them to annual accumulations of normal background radiation. Japan has a very serious problem, and so far, California is perfectly safe; much safer than the background radiation in most places.
A year's normal background radiation dose is about 2,600 μSv. It's double that in Denver.
A chest X-ray is about 25 μSv, and an abdominal X-ray is about 50 μSv.
A chest CT scan is about 10,000 μSv, and an abdominal CT scan is about 20,000 μSv, per scan. In other words, enjoying 40 years in La Jolla will get you as much radiation as one CT scan. La Jolla is perfectly safe – today.
By comparison, the levels measured in Japan have peaked as high as 400,000 μSv/hr (400 mSv/hr). In 11 hours at 400 mSv/hr, you'll get a 4,400 mSv dose, or enough to kill you.
See also this chart, whose caveat at the bottom I find particularly relevant.
These California readings are all trivially low background levels.
This is a negligible amount of normal background radiation, and even lower than expected. At these levels, the meter needle is barely coming off "0" and isn't even making it to the lowest part of its scale.
I'm impressed at the low levels. My condo is downwind from General Atomics, who has I-don't-want-to-tell-you-what, and upwind from MCAS Miramar, who has I don't know what, but sure can guess. My condo is 35 miles south of the San Onofre Nuclear Generating Station (SONGS). It's a testament to America that I live so close to these installations, and there's nothing I can detect. People in Denver get more radiation from the sky.
Just for fun, my neighbor took my SPER Scientific 840007 Radiation Detector on a drive up and down the I-5 past SONGS, and the readings were exactly the same as they read elsewhere. In other words, the plant is so well shielded and operated that there was no more radiation detected than in my own front yard.
In fact, the biggest source of radiation in La Jolla is our granite counter tops. A reading near my kitchen countertops' backsplash read 37 CPM, or double the readings taken outdoors.
My little Radiation Detector draws 22mA from its 9V battery, more if it has to click a lot, which so far, it's not. Let's hope it stays that way.
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