How clean is clean?

janitorHow clean is clean? Does something have to be spotless to be considered “clean” or is it good enough to be “clean enough?” And, if the latter, how good is clean enough? Bringing the matter home – should I insist that my sons’ room be spotless continually, or can I tolerate a little bit of slop to give them time to do their homework, pursue their personal hygiene, and participate in some sort of social life? Or, more to the point of this particular blog, after a dirty bomb attack do we insist on cleaning everything up to pre-attack levels or is it OK to leave a little bit of contamination behind as long as the risk isn’t too high?

The government has taken a stab at answering this question in the past and has recently done so again. And every time the recommendation comes down in favor of leaving a little bit of contamination behind the government catches a lot of flack – most recently last week.

I alluded to this problem in a recent post in which I discussed the matter from the standpoint of a concerned father. No matter how much the scientist in me might be convinced that residual contamination levels pose no risk to my kids, the father in me is going to have concerns. The question is not whether or not I can suppress these concerns but, rather, whether or not I can reconcile the opinions of both scientist and father.

Part of the problem is that most people have a visceral reaction to radiation and radioactive contamination. And when someone has an emotional reaction it’s hard to convince them with scientific evidence and reasoning. Even more difficult when they have an emotional stake (a child perhaps) in the fight.

The science behind the suggested governmental standards is fairly straight-forward – radiation can be harmful, but low levels of radiation exposure aren’t nearly as harmful as many people think. Not only that, but there are loads of people who live in natural high-background radiation areas who see to tolerate the radiation without any apparent harm. So leaving some contamination on the ground might seem sloppy, but up to a point it doesn’t pose much of a risk – certainly less than the risk from driving.

So maybe there’s not a strong health and safety argument for cleaning up to background levels, but there’s still the aesthetics to consider – even if the health risk is minimal, shouldn’t we try our utmost to restore a site to its original, pre-contaminated condition?

Nice in theory, but the practice makes things more difficult. Characterizing background radiation levels can be difficult, and we have to remember that instruments give results that vary slightly from reading to reading. Say I measure background radiation levels at 10 microR/hr (don’t worry about the units for the moment – just the magnitude of the reading) and that a dirty bomb goes off and raises background radiation levels to 1500 microR/hr. Where do we stop our cleanup? If I get a reading of 15 microR/hr does this mean that there’s still traces of contamination remaining or am I looking at a statistical fluctuation in background radiation readings? Or maybe I’m using a different meter than previously – maybe all of the contamination has been cleanup up, but the new meter just reads higher. All of these are plausible – but which one is the actual case (and how can I find out)? And on top of that, does it really matter?

The fact is that it’s not easy to know when we’ve reached background, so it’s not uncommon for cleanup to proceed to a certain level above background. This is the case for universities, for nuclear power plants, and even for cleanups overseen by the Environmental Protection Agency (EPA). So if the typical standard is that it’s OK to leave a little bit of contamination behind for environmental restorations or for the release of facilities and equipment for unrestricted use, why should it be any different in the aftermath of an RDD attack? And further – it might make sense to make a radioactive materials licensee remove as much contamination as possible, but what should be the standard in the aftermath of a terrorist attack? Can we cut ourselves a little bit of slack? This is the question that the recent government guidelines were attempting to answer.

The Obama administration has been taking unnecessary criticism over this set of recommendations. Those who oppose these relaxed limits are overlooking the fact that society will have a ton of concerns after a dirty bomb attack and radioactive contamination is only a small part. Consider – setting lower cleanup levels means cleaning up a larger area which costs more money. It also means that the cleanup will take longer – putting displaced residents and businesses in hotel rooms or temporary quarters for a longer period of time. Not only that, but consider the cost of cordoning off valuable parts of a city for longer periods of time, and the cost to a city from the loss of tourism, tax revenues, and jobs. The longer a chunk of territory is out of commission the greater the cost – monetary, social, and sociological – to the city and its residents. Does it make sense to double cleanup time and to quadruple cleanup costs – not to mention the other economic factors mentioned above – when a city is trying to get back on its feet?

One other factor to throw into the mix is the cost to a displaced population – not the monetary cost so much as the social and health costs. A 2006 study by the World Health Organization found that the greatest health costs to those displaced by the Chernobyl accident was the mental health cost – anxiety, substance abuse, suicide, and so forth, all of which skyrocketed in the aftermath of the accident, and all of which remain elevated even today. The mental health toll from Chernobyl –particularly among those who were forcibly evacuated – is at least as great as the health toll from radiation exposure. If we look only at the health risks from radiation exposure to the exclusion of everything else – economic, sociological, mental health, and so forth – we are making decisions based on incomplete information. We simply have to accept that fact that radiation might be a significant concern, but it is not the only concern in such situations.

In my opinion, many critics are taking cheap (and scientifically indefensible) shots at the administration. The administration doesn’t have the luxury of focusing on only one aspect of this problem – they have to consider all of the ramifications of their policy. Those who focus on radiological issues to the exclusion of everything else are simply missing the big picture –either through ignorance or willfully – and in so doing, they are doing society a disservice.

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