Americans receive a steady stream of warnings and alarms about new and horrific perils that await them. Pandemics, dirty bombs, cyber attacks, bioterror and other exotic threats are always on the verge of being unleashed onto a shamefully unprepared republic. Yet, judging from statistics on life expectancy, violent deaths and war, we live in much less perilous times than any generation before us. Avian flu, for example. We are cautioned that a pandemic...is only months away. One World Health Organization estimate says 2 million to 7 million people will die in the next pandemic. But it is not 1918. The WHO reports that since 2003, there have been 152 cases of avian flu, resulting in 83 deaths. A flu pandemic has been regularly predicted since 1997 and (knock on wood) it has never arrived. Dirty bombs -- conventional explosives mixed with radioactive material -- present another example of overreaction. In 2004, experts warned in the normally staid Wall Street Journal that a terrorist attack with a dirty bomb was an imminent certainty. They announced: Shame on our leaders and on us if the lamentations of the next blue-ribbon panel will be intoned over the graves of hundreds of thousands of Americans, the collapse of our economy, and perhaps a fatal blow to our way of life." But the Nuclear Regulatory Commission says a dirty bomb would contaminate "up to several city blocks." The commission's advice, if one goes off, is to walk away and take a shower.