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Dread risk” was characterized by Paul Slovic in his classic 1987 article in terms of its “perceived lack of control, dread, catastrophic potential, fatal consequences, and the inequitable distribution of risks and benefits.”  The key terms in that description is perceived.  Slovic provides evidence that expert judgments of risk sometimes run counter to judgments by lay people, and he provides nuclear power as a canonical example.  Most experts find nuclear power to be a relatively low risk technology, whereas the public finds it to be high risk. The difference has to do with “dread risk.”

Former Japanese Prime Minister Nato Kan this week provides a clear example of “dread risk” this week:

Former prime minister of Japan, Naoto Kan, said he experienced a “spine-chilling” feeling when he thought that Tokyo might have had to be evacuated in the aftermath of the Fukushima nuclear accident.

In an interview published on Tuesday, Kan said he feared Tokyo and its vicinities might have been rendered uninhabitable by the nuclear catastrophe, and that it would have been “impossible” to evacuate the 30-million population living in the area.

“Deserted scenes of Tokyo without a single man around came across my mind,” he was quoted as saying in the interview published by Tokyo Shimbun newspaper. “It really was a spine-chilling thought”.

The former prime minister said that he thought nuclear plants were safe, thanks to Japan’s technology. “I changed my mind” after this spring’s disaster, he added.

If the uninhabitable zone around the Fukushima plant had to spread out to 100 or 200 kilometers, “Japan wouldn’t stand as a country”, Kan said.

His conclusion was that, taking into account the risk, there is no choice but to become independent of nuclear power plants. If an accident that could make half the country uninhabitable is possible, that risk cannot be taken, “even if it was once in a century”, Kan said.

This scenario does not seem to jibe with any expert assessments of risk that I am aware of, and much of the discussion of the Fukashima disaster has focused on trying to accurately characterize the risksassociated with the aftermath of the tsunami.

But such a characterization is likely to miss the point — dread risk is real, and every bit as meaningful as the quantitative risk assessments so often provided by experts. For instance, this study (PDF)conducted in the aftermath of 9/11 looked that the consequences of fear of flying (“dread risk”) in automobile fatalities for the 3 months after the September 11, 2011. With less people flying and more driving, and because driving is riskier than flying (in terms of mortality rates), the study argues that there were 353 additional highway deaths than would have otherwise been the case.

In this case the cost of mitigating “dread risk” was tangible — 353 lives. Was that trade-off worth it to the public?  One answer is yes, because dread risk is real, people will be willing to pay some price to reduce it.  Another answer is no, because the public never really had a chance to make such a trade-off, at least not explicitly.

Many experts will argue that the answer here would be to better educate the public.  But in his 1987 article  Paul Slovic suggests caution,

Attempts to “educate” or reassure the public and bring their risk perceptions in line with those of industry experts appear unlikely to succeed because the low probability of serious reactor accidents make empirical demonstrations of safety difficult to achieve.  Because nuclear accidents are perceived as unknown and potentially catastrophic, even small accidents will be highly publicized and may produce large ripple effects.

Slovic continues:

Perhaps the most important message from this research is that there is wisdom as well as error in public attitudes and perceptions.  Lay people sometimes lack certain information about hazards.  However, their basic conceptualization of risk is much richer than that of the experts and reflects legitimate concerns that are typically omitted from expert risk assessments. As a result, risk communication and risk management efforts are destined to fail unless they are structured as a two-way process.  Each side, expert and public, has something valid to contribute.  Each side must respect the insights and intelligence of the other.

Dread risk is real and has costs. In the case of nuclear power, to the extent that nations such as Japan and Germany eschew nuclear power due to concerns about dread risks, their will inevitably be a price to pay.  Such costs will be in the form of greater reliance on fossil fuels and more expensive energy.