In other spheres of our lives, such as fires, we adopt a common sense attitude toward false alarms. Our local governments maintain expensive firefighting forces, even though in some small towns they are rarely called on to put out fires. Of the fire alarms phoned in to fire departments, many prove to be false alarms, and many others involve small fires that the property owner himself then succeeds in putting out before the fire engine arrives. We comfortably accept a certain frequency of such false alarms and extinguished fires, because we understand that fire risks are uncertain and hard to judge when a fire has just started, and that a fire that does rage out of control may exact high costs in property in human lives. No sensible person would dream of abolishing the town fire department, whether manned by full-time professionals or volunteers, just because a few years went by without a big fire. Nor would anyone blame a homeowner for calling the fire department on detecting a small fire, only to be succeeded in quenching the fire before the fire truck's arrival. Only if false alarms become an inordinately high proportion of all fire alarms do we feel that something is wrong. In effect, the proportion of all fire alarms that we tolerate is based on subconsciously comparing the frequency and destructive costs of big fires with the frequency and wasted-services costs of false alarms. A very low frequency of false alarms proves that too many homeowners are being to cautious, waiting too long to call the fire department, and consequently losing their homes.
By the same reasoning, we must expect some environmentalist warnings to turn out to be false alarms, otherwise we would know that our environmental warning systems were much to conservative. The multibillion-dollar costs of many environmental problems justify a moderate frequency of false alarms. In addition, the reason that alarms proved false is often that they convinced us to adopt successful countermeasures. For example, it's true that our air quality in LA today is not as bad as some gloom-and-doom predictions of 50 years ago. However, that's entirely because LA and the state of California were thereby aroused to adopt many countermeasures (such as vehicle emission standards, smog certifications, and lead-free gas), not because initial predictions of the problems were exaggerated.
