Ash cloud and swine flu anniversaries: lessons on the polarisation of risk

It’s roughly the second anniversary of the kicking off of the 2009 H1N1 influenza pandemic, and the first anniversary of the European ash cloud airspace closures.

There are some interesting parallels between these two events. Both were unexpected to some degree—in the case of the impact of the Eyjafjallajokull eruption, spectacularly so.

In retrospect, the surprise is a little surprising. It’s common knowledge that Iceland has volcanoes, and sometimes violent ones. Well within historical times, ‘killer clouds’ from such eruptions are believed to have caused thousands of deaths throughout Europe. Historians and volcanologists researching the 1783 Laki eruption would probably have agreed on the calamitousness of a similar event occurring today; but they may also have recognised, at least intuitively, that planning for such an unlikely disaster has its limitations. In the event of a catastrophic sulphur dioxide smog from an Icelandic volcano, it would be impossible to provide the entire population of western Europe with breathing masks. Having a detailed ‘Laki Eruption Crisis Plan’ might seem like overkill. Where do you draw the line: the Canary Islands Megatsunami Mitigation Plan, or the Comet Impact Plan?

Which is not to say stuff wouldn’t be done. In the event of a Laki-like eruption, modern communications technologies would allow rapid dissemination of expertise from parts of the world that do have to contend with these sorts of problems. At least modern housing would provide some refuge, particularly against particulates, compared to 18th century buildings. Weather forecasting and strong health systems— allowing identification of high risk groups— would allow mapping of risk and preventive measures to reduce the overall population health impact. It would be disastrous, but the continent would go into ‘crisis mode’ and solutions would be sought and implemented rapidly.

So I can see why the people paid to consider these possibilities may have been simultaneously alarmed/reassured, and generally resigned to not thinking too much more about such an event, at least in terms of detailed ash cloud-specific emergency planning. Or perhaps they just couldn’t get their warnings heard; Andrew Revkin recently pointed out— in the context of the Japanese tsunami— that lessons from history are quickly forgotten by the people who matter.

But what actually happened was something much less calamitous than 1783. No suffocating smog or crop failures; instead, a problem unique to just one part of one aspect of modern civilisation— the vulnerability of turbojet engines to fine airborne volcanic ash which melts and solidifies on turbine blades, stopping them from turning. (Interestingly, old fashioned carburettor-filtered piston engines would have been much more resistant to the cloud.)

This had been identified as a problem from flights through eruptions elsewhere, so someone might have been reasonably expected to flag this up as a potential issue for European airspace, in advance of the wrong kind of Icelandic eruption and an unfortunate wind direction. But perhaps our collective perception of risk tends to be polarised towards one extreme or the other: in a Laki-like eruption, this would just be one of a cascading series of problems of equal or worse severity. We seem to find it hard to make connections between relatively minor incidents (such as the 1982 Speedbird 9 flight) and major ones (such as a 1783-like Laki eruption). So on the face of it we don’t anticipate the intermediate crises— like last year’s ash cloud— very well, and according to the Daily Mail and its ilk, we overreact.

2009’s swine flu outbreak was also unexpected, at least in terms of timing. The big difference here is that public health bodies had been warning of a new flu pandemic for some years; SARS and avian flu had primed authorities for the possibility, while the 1918 flu pandemic (which killed more people than the world war it followed) is still less than a hundred years ago. Most developed nations had (and still have) detailed pandemic flu plans in place, and were able to implement them rapidly.

Generally, these plans assume a worse case scenario. Here in the UK, this involved resource-intensive active case finding for a period that was probably more prolonged than the severity of the disease really warranted, and the almost indiscriminate dishing out of the antiviral drug oseltamivir. When swine flu turned out to be reasonably mild, authorities were accused of overreacting.

So again, the human perception of risk seems to be polarised towards one extreme or the other, and again, we haven’t dealt with a ‘middling’ threat very well. In these situations we either have proscriptive, over-detailed and inflexible response plans, or we just haven’t seen it coming.

[Seems like a neat way to finish, but in reality a gross simplification. The emerging consensus is that we probably did OK in both the examples discussed here, obviously with lessons for the future (as long as we can remember them long enough for the next time). See here and here. It’s a shame when the facts get in the way of a good discussion point…]

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