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Getting risk wrong

People are notoriously bad at assessing risk. That is, at correctly distinguishing between decisions based on fact and those based on opinion, or to put it another way, decisions based on the head and those on the gut. We tend to overrate some risks and underrate others, often without any apparent logical basis. Much of the work of skeptical organisations and campaigners for critical thinking is generated by this inability to separate emotion from cold hard analysis.

I live in the Blue Mountains, west of Sydney, an area at high risk of bush fires. While the gut tells us that this is a dangerous place to live the heart tells us to look at the views and breathe the clean air. If a serious fire broke out in the valley at the end of my street and a southerly wind happened at the same time there is a real possibility that large parts of at least three towns would face the potential of evacuation, even if only to get away from smoke and flying ash. The evacuation of several thousand people would have to be done over single-lane roads which themselves pass through fire-endangered areas. It is interesting to read the letters to editors of the local papers to see that many people seem to ignore the fire risk and are more worried about house burglaries and the occasional piece of graffiti. Residents of suburbs closer to the centre of Sydney might think that the crime and graffiti rates in the mountains are not worth worrying about or perhaps unmeasurable, but everything is relative.

Another interesting theme in the letters pages is opposition to widening the single access (and escape) road to the area. To some people the thought of more trucks passing near their houses is more worrying than the thought of dying in their cars while trying to get out of their street onto the highway. Part of the problem is that there hasn't been a big fire in the area since 2001, and 1994 before that, and even severe outbreaks since then have been controlled without loss of life or much property, so many newer residents have only their imaginations to tell them of the risk.

An aspect of risk management that is emphasised by fire services is the necessity for an action plan in the case of a fire, with particular attention to the decision between staying to defend property or getting out as soon as possible. The decision is a little easier for me because I rent so there is not a lot of incentive to hang about saving the landlord's property, but I have always thought that the choice between waiting until the last minute and getting out early was a simple one. Staying not only increases the risk of death or injury but also increases the risk of not being able to escape if the decision turns out to be the wrong one – many of the people who died in the 2009 Victorian fires did so because the escape routes were closed by the time they decided to use them. As I said above, however, even with this recent experience there are still people who can't see the benefit of good roads in and out of an area where roads will be essential in case of a disaster.

I knew about the fires before I moved here, and as I said above I balanced the risk of fires against the benefits of a mountains lifestyle. What I didn't know, though, was the fragility of the infrastructure. A recent storm in the area left us without electricity for four days because of damage to wires and substations. Because we live almost a kilometre above sea level water has to be pumped up to the area, so water restrictions were immediately applied. A good water supply is an essential resource for fighting fires, of course. The local telephone exchange found that the risk assessment for the need for backup supply had been wrong and the backup batteries failed, leaving us with no fixed-line telephone or Internet access (and without electricity it was impossible to charge mobile phone batteries). A tree fell on a train, taking out the overhead power lines and blocking the line for several days while the wreckage was removed and the damage repaired. So we were without electricity, telephone, Internet and public transport and with a restricted water supply in a town where you can see Sydney from the train station. A further complication for our particular house was that a falling branch had taken out just one wire from a pole in a nearby street, so even after the supply had been restored to the suburb there were still some houses, ours among them, which had no lights because one of the supply phases was missing.

Should I be concerned about this sort of thing happening again and manage the risk by, for example, buying a generator to keep power on to the house? (We were able to borrow a small generator to keep the lights and computer on, and a gas picnic stove served to boil water for coffee.) The answer is "Probably not". The coincidence of events that happened that day was extremely unlikely and what we suffered was inconvenience with no risk to life or property. I have, however, updated the list of alternative accommodation places that was already part of the home bush fire disaster plan.

I recently travelled from Sydney to Brisbane and Melbourne by train to attend a couple of conferences. (I live about three hours by train or a $150 taxi fare from the airport in Sydney, so it is cheaper, more convenient and surprisingly similar in overall travel time to go by train.) I know at least one other person made an interstate train trip to the Brisbane event but most of the delegates who came from outside Queensland or Victoria travelled by air, although some went by bus or car. Many of the locals drove to the conference.

Glenbrook, 1999Most people will be aware of Australia's exemplary record of air travel safety. It is in fact the safest means of transport in Australia, including walking or being pushed in a pram, when calculated by fatal incidents per passenger kilometre. Motor vehicles kill about two thousand Australians each year,  around 800 people have died on the road between Sydney and Brisbane in the last two decades, and there have been at least two serious long-distance coach accidents (Kempsey (1989, 35 deaths, 41 injured), Grafton (1989, 21 deaths, 22 injured)). On my train trips I passed through places where more than a hundred people have died in rail accidents over the last few years (Glenbrook (1999, 7 deaths), Cowan (1990, 6 deaths), Violet Town (1969, 8 deaths) and Granville (1977, 83 deaths, 200 injured)).

The surprising thing is that the form of travel most feared by people is going by air, the safest form of all. There is a good business in providing Fear of Flying courses and everyone is worried about the dreadful effects of jet lag and stroke from deep vein thrombosis. Whenever an air crash is reported in the news there are flight cancellations in the ensuing weeks. Contrast this with the fact that despite constant advertising about road safety people continue to drive without seat belts or when intoxicated. The train trip from Brisbane to Sydney takes longer than the plane flight from Sydney to Los Angeles, but I have never heard anyone express concern about deep vein thrombosis on the train.

Granville, 1977Part of the problem is a combination of familiarity and what the psychologists call availability. For most people, the frequency of reading about or seeing images of plane crashes is greater than the frequency that they actually get to sit in a plane, and those reports and images are always very graphic, with survival often attributed to a miracle. Car travel, on the other hand, is something we do all the time and even though we see the safety advertisements most people don't know anyone who has been killed in a car. We know from personal experience that car travel is safe so the warnings are ignored. Commuters catch trains ten times a week so again they can use their gut to tell them that train travel is safe. I lived at Penrith at the time of the Granville train crash in 1977 and everybody I knew in the area knew at least one person who died, but we all got back on the train the next day to go to work.

As well as the constant barrage of information about car safety which seems to be disregarded there are other well publicised health risks which are widely ignored. Smoking kills ten times as many Australians as cars do but people still smoke, and nobody could be unaware of the dangers of cigarettes. Advertisements on the television warn us of the danger of skin cancer from tanning but there seem to be solariums in every large shopping centre.

Similarly with bush fires. These are events which happen on television to other people.

A large part of the resistance to warnings of climate change and its potential effects is due to the fact that people simply cannot imagine that these dreadful consequences could happen. People associate ice ages turning Germany, France and the UK into Siberia with woolly mammoths and animated feature films, not with a southerly shift of the Gulf Stream caused by ice melting in Greenland. As I write this parts of Bangkok are being flooded but instead of this being a warning of the possible fate of Sydney, Melbourne, London, Tokyo, San Francisco and Manhattan if sea levels rise it is again dismissed as something unfortunate happening to other people. New Orleans in 2005 was just one of those things you expect when a city is built below sea level in a hurricane zone, and the idea that hurricanes are getting fiercer and sea levels might be rising are just suppositions, not anything to worry about. After all, the city had been flooded by storm surges before and managed to survive.

Sweet Poison – SugarSo we have very well publicised dangers which are ignored by a large proportion of the population, but the really strange thing is how the public reacts to dangers which are not publicised by scientists or responsible government authorities but by people with no qualifications or with agendas to promote or books to sell.

Sweet Poison – AspartameThe archetypical example of books by unqualified people which exaggerate dangers and yet are readily accepted by large numbers as identifying real risks are diet books. I have in front of me two books (with coincidentally the same title) warning of the dangers of aspartame and fructose respectively. Both have had very good sales and have generated wide public comment and concern about the deadliness of the two chemicals in question, but both are written by authors with no training in either science or nutrition.

Mobile phone danger seems to be a perennial story in the media. I got my first mobile phone before the world wide web had been invented, but I am sure that there must have been people using their Roneo machines to run off fliers warning of the dangers and then attaching them to lamp posts with sticky tape. I remember seeing someone very concerned about mobile phone radiation danger using a hands-free earpiece. All very safe against brain cancer, but he had the handset sitting in his lap. I thought at the time that he hadn't thought things through very well.

Apparently there are more mobile handsets in Australia than people, so if there is any problem with them then it has the potential to be a very big problem indeed. The facts are, however, that the power of an individual handset is very low (your microwave oven puts out about 4,000 times as much power) and the wavelength of the radiation means that it cannot destroy DNA or the cells around it.

The number of handsets in use around the world, the decades over which the phones have been in use, and the apparently almost unmeasurable rate of problems like brain cancers which can indisputably be blamed on the phones should be enough to make people feel safe using them. Until the next scare story in the paper comes along.

There are entire industries built on overstating risk. One is the "organic" food movement which makes a lot of noise about genetically-modified foods without acknowledging that wheat, corn, broccoli, canola and many other staple food plants are very far removed from their "natural" origins. We have been eating genetically-engineered wheat for a long time and adding genes in a controlled fashion would seem to be a better and safer proposition than spreading pollen around and hoping for a good result.

Alternative medicine relies on faulty perception of risk for its survival. As an example, I am often told that the fact that a drug is only available on prescription means that it is inherently extremely dangerous, but of the two drugs I carry with me when I travel (metformin and paracetamol) the prescription-only one has no known toxic dose but a deadly amount of the over-the-counter drug can be bought in any supermarket for less than ten dollars. I hear daily about the dangers of psychiatric drugs, the chemicals and radiation used to treat cancer, of fluoride in the water, of statins used to control cholesterol, even of mammograms to detect breast cancer, all without admitting that there might be any benefit to balance the risk.

A Pap smear positive for cervical cancerAn extension of alternative medicine is the anti-vaccination movement, which takes the process even further by minimising the risks associated with diseases while simultaneously exaggerating the risks of the vaccines themselves. Who doesn't get a feeling in the gut that danger to children should be avoided? And who has ever seen a case of polio or diphtheria?

A current and topical example of this is the campaign against the vaccine to prevent cervical cancer. This is a disease which kills about 250,000 women around the world each year, but which is comparatively rare in Australia. This rarity is because we have had for some time a very effective screening process to detect early warning signs of the disease, but this rarity is used as a reason to emphasise (and often hugely and sometimes dishonestly exaggerate) the risks associated with the vaccine. There is even the suggestion that the risk of the Pap smear (risk which would seem to extend no further than the embarrassing nature of the sample collection process) is too great when compared to the incidence of the disease, an incidence which, as I said above, is rare largely due to the use of this particular test, just as the rarity of polio and diphtheria in Australia is due to vaccination.

Skeptics often try (and fail) to correct people's misconceptions by the application of science and reason. We need to recognise that when decisions are made with the gut rather than the head that another approach is required. One day I hope to work out what this approach might be.

This article was published in Issues magazine in December 2011

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