(Editor: This story has rectified information on how levels of radioactive iodine-131 detected in the air in Canada after Fukushima compared with the Canadian Nuclear Safety Commission’s ceiling for iodine-131. The original story mistakenly said that ceiling was exceeded. We regret the error.)
Confused by all the nuke lingo about becquerels and sieverts and what it means for your health? So were most of the nuclear experts we talked to for this story.
It also doesn’t help that Health Canada’s data on the radioactive fallout from Fukushima is so sparse and confusingly reported that it’s hard to figure out whether or not it exceeds government limits.
Health Canada reports on monitoring data for only three or four of the hundreds of radioactive substances spewing out of the crippled Japanese nuclear plant.
Canada also has only five monitoring stations that contain equipment sensitive enough to notice levels of specific radioactive substances from Fukushima in the air.
“They’re measuring only a fraction of the radioactive fallout from Fukushima,” said Gordon Edwards of the Canadian Coalition for Nuclear Responsibility, speaking from Montreal.
In contrast, the U.S. Environmental Protection Agency has 200 monitoring stations checking for up to 11 radioactive substances in everything from air and milk to drinking water and rainwater.
Health Canada’s radiation-monitoring webpage downplays any fallout concerns, saying radiation reaching Canada has been “within normal background levels”. That’s based largely on data from a second network of 35 other monitoring stations that have less sensitive equipment (including 12 in B.C.).
But an analysis of the data from these stations shows radiation levels did hit sustained above-normal levels for an average of 36 days in March and April after Fukushima. The radiation level rose to 0.48 microsieverts per day, on average, during this time, up from 0.43 seen in the rest of the monitoring data between March 10 and July 27—or an increase of 11 percent.
Of all the B.C. sites, the biggest spike was in Victoria, where the level rose from 0.23 to 0.25 microsieverts per day between March 19 and 25—an increase of 9.9 percent. Vancouver saw a four-percent increase, from 0.43 to 0.45 microsieverts.
The worst-hit city in Canada was Regina. It saw a 90-percent spike in its radiation level, from 0.36 to 0.69 microsieverts per day. Yellowknife was second-highest with a 31-percent jump, followed by Toronto with a 26-percent rise.
But this data downplays the radiation from Fukushima, Edwards said. The less sensitive equipment also picks up large amounts of background radiation from natural sources like the sun and soil.
It also doesn’t spot jumps in the type of radioactive substances released in a nuclear accident, like iodine-131. Another problem: sieverts are a questionable way to measure radiation because they include a subjective calculation of the radiation’s impact on a person, and so the results can be manipulated to play down impacts, Edwards said.
“It’s a shell game. Microsieverts are quite a distance removed from the raw data. They’re blending in stuff from nature to make the data look innocuous,” he says.
You have to scroll down to the bottom of Health Canada’s radiation webpage to find the more striking data from the five stations monitoring specific radioactive substances.
This data shows the air at the five stations showed highly elevated levels of iodine-131 and three other radioactive substances during 30 days on average.
The level of iodine-131 in Sidney, B.C., rose to a high of 3.63 millibecquerels per cubic metre in the air on March 20. That’s over 300 times higher than the background level of 0.01 millibecquerels per cubic metre or less.
The highest level of iodine-131 recorded in the country was in Resolute Bay, Nunavut, where the concentration reached 9.76 millibecquerels per cubic metre. (or nearly 1,000 times higher than the background level).
Also in Sidney, the level of radioactive cesium-137, which has a half-life of 30 years, shot up about 40-fold, from a background level at or below 0.01 millibecquerels per cubic metre to a high of 0.4 millibecquerels per cubic metre on March 25.
Those levels were individually well below the maximum ceilings permitted by the Canadian Nuclear Safety Commission, which for iodine-131 is 200 millibecquerels per cubic metre of exposure in the air on a daily basis for an entire year.
But when all of the radioactive material that was detected is combined together—along with unknown exposure from many other radioactive substances not being monitored by Health Canada, like strontium-90 (which has a half-life of 29 years) and plutonium-239 (with half-life of 24,000 years)—the radiation still poses a health risk as it concentrates and becomes more potent in the food chain, said Gordon Edwards of the Canadian Coalition for Nuclear Responsibility.
“There is no safe level of radiation. What may be acceptable for individual exposure may not be acceptable when millions of people are exposed. It’s important to measure the cumulative impact of all the isotopes, but only a small fraction are being measured,” Edwards said.