Month: November 2011

Sievert and Becquerel, Oh Dear!

Posted on . by Patrick Johnstone. Leave a comment.

So the Georgia Straight sort of tries to clarify things in this article, and not surprisingly, fail miserably.

The article starts out pointing out how confusing all the data is, then does nothing but muddify the fuzzification (as Dr. Foth used to say) by throwing out more random numbers and units lacking context, and never once mentioning what the units mean. They complain that Environment Canada’s data is confusing, but do nothing to provide more clarity. The impression they leave is that Health Canada, by releasing the radiation data from Fukushima, is actually involved in a conspiracy to cover it up.

I already talked about Becquerel, so you should realize that the exposure listed in the following quote is one millionth of the exposure you receive from your own bones:

” The level of iodine-131 in Sidney, B.C., rose to a high of 3.63 milliBecquerel per cubic metre in the air on March 20. That’s over 300 times higher than the background level of 0.01 milliBecquerel per cubic metre or less.”

Oh, and that “background” value? There is no natural background value for Iodine 131, it is not a naturally occurring element in any quantity (it is a product of uranium fission), and has a short half-life (8 days) in real-world terms, so any of it that is created naturally goes away really quick. What they are falsely calling “background” is actually the Method Detection Limit (“MDL”), or the smallest concentration that can be detected using the equipment available. Note that Cesium-137, later in the article, has the same “background” concentration.

It is interesting to note that the acceptable level of Radon in your home is 200 Becquerel per cubic metre. So your daily exposure in your home, where you breathe 8 hours a day 365 a year is not significant health concern at 50,000 times the level of that one-day spike in Sidney.

But what about Sievert? According to the article:

“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,”

. This is one of the most ignorant anti-science statements I have read in printed media in a long time. Sieverts confuse this poor idiot, so he assumes someone is pulling the wool over his eyes. We are not too sure who, and what their nefarious plan is, but this writer is finding conspiracy every time someone uses a term he does not understand. Instead of trying to understand it, he assumes the worst. That is the difference between skepticism and cynicism.

It really isn’t that complicated, and if he did a little research, he would discover that the calculation of “effective dose” does the exact opposite of what he says: it combines together the cumulative impacts onto a single unit, allowing us to compare radiation apples to radiation oranges.

Not all radioactive substances are the same. When they decompose, they release various different types of radiation and/or particles. So in that sense, a counting of Becquerel (like I have been doing for the last two posts) tells us about the amount of atom decay, but does not tell us about the harm each decay may cause.

When an atom of Potassium-40 in your bones decays, it (most often) releases an electron at very high energy (<1.3meV), and a neutrino. The neutrino is harmless (or at least it is drowned out by the 60+ billion of them that pass through every square centimetre of your body every second you are alive on earth) but the electron at that energy level is called a beta particle, and is a form of ionizing radiation that can cause cellular damage. When Iodine-137 decays, it does a little two-step decay that results in a beta particle followed very shortly by a gamma ray. Uranium-238, in contrast, releases an entire helium nucleus, otherwise known as an alpha particle. Each of these particles pack a different “punch”, a they carry different abilities to interact with other materials.

The unit “Grey” is used to convert the varying doses delivered by a unit of each of these types of radiation into one convertible unit. It is a little more complicated than this, but essentially, because an alpha particle is bigger and interacts more strongly with other materials, it packs 20x the “dose” of a gamma ray or a beta particle (which pack about equal doses). So one unit of alpha radiation packs the punch of 20 units of gamma or 20 units of beta. It also stands to reason that these three types of radiation (alpha, beta and gamma) are differently harmful to health. Alpha particles are big and heavy, so they cannot penetrate your skin very far (only a few micrometres), and actually can only travel a few metres through the air before being absorbed by the atmosphere. Therefore, direct exposure to alpha radiation tends to cause things like radiation burns. Beta particles are smaller, with more energy, and can travel through the air pretty freely, but only penetrate several centimetres into your skin, causing deeper damage. Gamma rays can pass through most materials (although lead does diffuse them quite a bit) and since they can pass right through your body, tend to cause systemic “radiation sickness” if you are exposed to a lot of them.

To further complicate matters, some tissues in your body (especially your bone marrow and lymph nodes) are more severely impacted by radiation than other tissues (like the skin or the liver). A single Grey of exposure will impact your lymph nodes more than your skin, so factors that account for these differences need to also be calculated if we want to understand the health effects of radiation. As the ultimate impact on your body are cumulative from all of the tissues affected, these tissue-specific factors are added together, and the sum value used to calculate the “effective dose” a person receives from any given amount (Grey) of radiation.

Since we are comparing three different types of radiation and dozens of different tissues, the unit must be standardized. The “effective dose” is measured in the Si unit “Sievert”, which is defined as the amount of radiation that has the equivalent biological impact as one joule of gamma rays adsorbed by one kilogram of tissue. You can look at this data table to put that number into perspective. The average North American is exposed to about 3 milliSievert (mSv) every day from natural sources (or 0.003 Sv), and can receive from 0.004 to 0.83 mSv from a medical or dental x-ray.

A microSievert is 0.001 milliSievert. So the radiation “spikes” mentioned in the Georgia Straight article, from 0.43 to 0.48 microSievert, or 0.23 to 0.25 microSievert, or even 0.36 to 0.96 microSievert, are much less than a thousandth of our daily exposure from things like the uranium in our granite countertops to the radium adsorbed in our rain to the potassium in our bananas (and notably, not the radio waves from our cell phones). And less than a hundredth of the exposure we would receive from a single dental x-ray.

The article does sum up with one of those great meaningless quotes: “There is no safe level of radiation.” I would suggest anyone in BC concerned about their increased exposure to radiation caused by Fukushima should probably eat one less banana this year, and you will more than offset any impacts

On Elections, Taxes, and Wages

Posted on . by Patrick Johnstone. 2 Comments.

Now I may be biased, seeing as how I work for a City, but I don’t work for New Westminster, so I am going to barge ahead with that potential bias exposed (sound like a declared conflict-of-interest?). There are currently at least two candidates in New Westminster who are talking taxes in a big way, and it seems they both think that City Workers get paid too much. Fair opinion, but are they arguing facts?

John Ashdown, sometimes referred to as the “Mayor of 12th Street”, is well known as both a community-builder and a fiscal conservative. His website includes the following quote:

”Do you know that 78% of your tax dollar ends up in to City Wages and Salaries?

Mayoral Candidate James Crosty was recently quoted by the Douglas College student paper making a very similar statement:

“80 per cent of every tax dollar that’s generated goes towards paying salaries in the city.”

His promotional newspaper is a little more conservative, downgrading that number to 78.08%. But the message is clear: the City pays so much of your taxes to the wages of City workers that they can hardly afford anything else form the 20% of the money that is left!

This first raised the question to me: is that high? I mean it sounds high, but I wonder if it really is compared to other cities, like Richmond, where I work. I asked these questions to Mr. Crosty at last night’s all-candidates mixer, and he suggested I make the comparison between New West and Richmond (presumably, a better-managed City in his opinion). However, before we compare the facts, let’s find out of they are facts.

Luckily, the City’s 2010 budget is available on-line for anyone to read. Now, I’m no financial expert. Tables of geochemical data generally make much more sense to me that tables with dollar signs on them, but we should be able to parse out the info here without too much trouble.

If we look at the amount of tax revenue generated in 2010, we get the nice, round number of $54,569,975 (page 10 of the .pdf, which is page 2 of the financial statements, first number, second column). So 80% of that is $43,655,980.

Now, if you scroll way, down to page 41 of the .pdf, you get a list of all salaries paid in 2010, notably excluding police: $40,430,379. That is about 74%. Close enough for politics.

Hopefully looking at these same financial statements, you see all the problems with this rough estimate. The $54 Million number only represents about a third of City revenue. The City’s annual revenue is actually more than $165 Million, when you include transfers from other governments, utility charges, and other revenue sources. If you want to be simplistic and call all of these “taxes”, then the $40 Million salary figure above only represents 24% of the money the City takes in.

In fact, a better count for the wages paid out is available on page 27 of the .pdf: including Police services, the City paid $64,034,085 in wages and salaries, or 117% of the tax revenue they take in!

Another way to look at it is to flip to page 48 of the .pdf. At the end of a long list of all the businesses to whom the City paid money for goods or services in 2010 is a grand total of $102,540,586.

Perhaps one of the candidates making the statements above can explain to me how a City that is took in $165 Million in revenue can spend 62% of that revenue on payments to suppliers of goods and services, and still spend 80% on staff salaries? Because I’m clearly not a financial genius, and I may have a bias here.

Finally, let’s compare New Westminster with Richmond.

New West collected $54M in property taxes in 2010, which represents 32% of their $165M in revenues. They pay $64M wages (including cops), and another $7M in contracted services, for a total of $71M. That total represents 43% of their revenue. So 43 cents of every tax dollar goes to wages and consultant fees.

Compare this to Richmond’s annual financial report. Note that Richmond collected $156M in Property Taxes, which is 41% of their $379M in revenue. In the same year, they paid wages to $116M and $49M in contracted services for a total of $165M. That represents 43% of their total revenue. Exactly the same as New West.