ON THE ESCAPE OF TIGERS: AN
ECOLOGIC NOTE
President, Insurance
Institute for Highway Safety
A major class of ecologic
phenomena involves the transfer of energy in such ways and amounts, and at such
rapid rates, that inanimate or animate structures are damaged. The harmful interactions with people and property
of hurricanes, earthquakes, projectiles, moving vehicles, ionizing radiation,
lightning, conflagrations, and the cuts and bruises of daily life illustrate
this class.
Several strategies, in one mix or another, are
available for reducing the human and economic losses that make this class of
phenomena of social concern. In their
logical sequence, they are as follows:
The first strategy is to prevent the marshalling of
the form of energy in the first place:
preventing the generation of thermal, kinetic, or electrical energy, or
ionizing radiation; the manufacture of gunpowder; the concentration of U-235;
the build-up of hurricanes, tornadoes, or tectonic stresses; the accumulation
of snow where avalanches are possible; the elevating of skiers; the raising of
babies above the floor, as to cribs and chairs from which they may fall; the
starting and movement of vehicles; and so on, in the richness and variety of
ecologic circumstances.
The second strategy is to reduce the amount of
energy marshaled: reducing the amounts
and concentrations of high school chemistry reagents, the size of bombs or
firecrackers, the height of divers above swimming pools, or the speed of
vehicles.
The third strategy is to prevent the release of the
energy: preventing the discharge of
nuclear devices, armed crossbows, gunpowder, or electricity; the descent of
skiers; the fall of elevators; the jumping of would-be suicides; the
undermining of cliffs; or the escape of tigers.
An Old Testament writer illustrated this strategy in the context both of
the architecture of his area and of the moral imperatives of this entire
field: “When you build a new house, you
shall make a parapet for your roof, that you may not bring the guilt of blood
upon your house, if any one fall from it.” (Deuteronomy 22:8). This biblical position, incidentally, is
fundamentally at variance with that of those who, by conditioned reflex, regard
harmful interactions between man and his environment as problems requiring
reforming imperfect man rather than suitably modifying his environment.
The fourth strategy is to modify the rate or spatial
distribution of release of the energy from its source: slowing the burning rate of explosives,
reducing the slope of ski trails for beginners, and choosing the reentry speed
and trajectory of space capsules. The
third strategy is the limiting case of such release reduction, but is
identified separately because in the real world it commonly involves
substantially different circumstances and tactics.
The fifth strategy is to separate, in space or time,
the energy being released from the susceptible structure, whether living or
inanimate: the evacuation of the Bikini
islanders and test personnel, the use of sidewalks and the phasing of
pedestrian and vehicular traffic, the elimination of vehicles and their
pathways from community areas commonly used by children and adults, the use of
lightning rods, and the placing of electric power lines out of reach. This strategy, in a sense also concerned with
rate-of-release modification, has as its hallmark the elimination of
intersections of energy and susceptible structure—a common and important
approach.
The very important sixth strategy uses not separation
in time and space but separation by interposition of a material “barrier”: the use of electrical and thermal insulation,
shoes, safety glasses, shin guards, helmets, shields, armor plate, torpedo
nets, antiballistic missiles, lead aprons, buzz-saw guards, and boxing
gloves. Note that some “barriers,” such
as fire nets and other “impact barriers” and ionizing radiation shields,
attenuate or lessen but do not totally block the energy from reaching the
structure to be protected. This strategy, although also a variety of rate-of-release
modification, is separately identified because the tactics involved comprise a
large, and usually clearly discrete, category.
The seventh strategy, into which the sixth blends,
is also very important—to modify appropriately the contact surface, subsurface,
or basic structure, as in eliminating, rounding, and softening corners, edges,
and points with which people can, and therefore sooner or later do, come in
contact. This strategy is widely
overlooked in architecture with many minor and serious injuries the
result. It is, however, increasingly
reflected in automobile design and in such everyday measures as making lollipop
sticks of cardboard and making some toys less harmful for children in
impact. Despite the still only spotty
application of such principles, the two basic requisites, large radius of
curvature and softness, have been known since at least about 400 B.C., when the
author of the treatise on head injury attributed to Hippocrates wrote: “Of
those who are wounded in the parts about the bone, or in the bone itself, by a
fall, he who falls from a very high place upon a vary hard and blunt object is
in most danger of sustaining a fracture and contusion of the bone, and of
having it depressed from its natural position; whereas he that falls upon more
level ground, and upon a softer object, is likely to suffer less injury in the
bone, or it may not be injured at all . . .” (“On Injuries of the Head,” The
Genuine Works of Hippocrates, trans. F. Adams [The Williams and Wilkins Co.,
Baltimore, 1939]).
The eighth strategy in reducing losses in people and
property is to strengthen the structure, living or non-living,
that might otherwise be damaged by the energy transfer. Common tactics, often expensively
under-applied, include tougher codes for earthquake, fire, and hurricane
resistance, and for ship and motor vehicle impact resistance. The training of athletes and soldiers has a
similar purpose, among others, as does the treatment of hemophiliacs to reduce
the results of subsequent mechanical insults.
A successful therapeutic approach to reduce the osteoporosis of many
post-menopausal women would also illustrate this strategy, as would a drug to
increase resistance to ionizing radiation in civilian or military experience. (Vaccines, such as those for polio, yellow
fever, and smallpox, are analogous strategies in the closely parallel set to
reduce losses from infectious agents.)
The ninth strategy in loss reduction applies to the
damage not prevented by measures under the eight preceding—to move rapidly in
detection and evaluation of damage that has occurred or is occurring, and to
counter its continuation and extension.
The generation of a signal that response is required; the signal’s
transfer, receipt, and evaluation; the decision and follow-through, are all
elements here—whether the issue be an urban fire or wounds on the battlefield
or highway. Sprinkler and other
suppressor responses, fire doors, MAYDAY and SOS calls, fire alarms, emergency
medical care, emergency transport, and related tactics all illustrate this
countermeasure strategy. (Such tactics
have close parallels in many earlier stages of the sequence discussed here, as,
for example, storm and tsunami warnings.)
The tenth strategy encompasses all the measures
between the emergency period following the damaging energy exchange and the
final stabilization of the process after appropriate intermediate and long-term
reparative and rehabilitative measures.
These may involve return to the pre-event status or stabilization in
structurally or functionally altered states.
There are, of course, many real-world variations on
the main theme. These include those
unique to each particular form of energy and those determined by the geometry
and other characteristics of the energy’s path and the point or area and
characteristics of the structure on which it impinges—whether a BB hits the
forehead or the center of the cornea.
One point, however, is of overriding
importance: subject to qualifications as
noted subsequently, there is no logical reason why the rank order (or priority)
of loss-reduction countermeasures generally considered must parallel the
sequence, or rank order, of causes contributing to the result of damaged people
or property. One can eliminate losses in
broken teacups by packaging them properly (the sixth strategy), even though
they be placed in motion in the hands of the postal service, vibrated, dropped,
piled on, or otherwise abused.
Similarly, a vehicle crash, per se, need necessitate no injury, nor a
hurricane housing damage.
Failure to understand this point in the context of
measures to reduce highway losses underlies the common statement: “If it’s the driver, why talk about the
vehicle.” This confuses the rank or
sequence of causes, on the one hand, with that of loss-reduction
countermeasures—in this case “crash packaging”—on the other.
There are, nonetheless, practical limits in physics,
biology, and strategy potentials. One
final limit is operative at the boundary between the objectives of the eighth
and ninth strategies. Once appreciable
injury to man or to other living structure occurs, complete elimination of
undesirable end results is often impossible, through appreciable reduction is
commonly achievable. (This is often also
true for inanimate structures, for example, teacups). When lethal damage has occurred, the
subsequent strategies, except as far as the strictly secondary salvage of parts
is concerned, have no application.
There is another fundamental constraint. Generally speaking, the larger the amounts of
energy involved in relation to the resistance to damage of the structures at
risk, the earlier in the countermeasure sequence must the strategy lie. In the ultimate case, that of a potential
energy release of proportions that could not be countered to any satisfactory
extent by any known means, the prevention of marshalling or of release, or
both, becomes the only approach available.
Furthermore, in such an ultimate case, if there is a finite probability
of release, prevention of marshalling (and dismantling of stockpiles of energy
already marshalled) becomes the only, and essential, strategy to assure that
the undesirable end result cannot occur.
Although the concern here is the reduction of damage
produced by energy transfer, it is noteworthy that to each strategy there is an
opposite focused on increasing damage.
The latter are most commonly seen in collective and individual
violence—as in war, homicide, and arson.
Various of them are also seen in manufacturing,
mining, machining, hunting, and some medical and other activities in which
structural damage often of a very specific nature is sought. (A medical illustration would be the destruction
of the anterior pituitary with a beam of ionizing radiation as a measure to
eliminate pathologic hyperactivity.) For
example, a maker of motor vehicles or of aircraft landing-gear struts—a product
predictably subject to energy insults—could make his product more delicate,
both to increase labor and sales of parts and materials, and to shorten its
average useful life by decreasing the age at which commonplace amounts of
damage increasingly exceed in cost the depreciating value of the product in
use. The manufacturer might also design
for difficulty of repair by using complex exterior sheet metal surfaces, making
components difficult to get at, and other means.
The type of categorization outlined here is similar
to those useful for dealing systematically with other environmental problems
and their ecology. In brief
illustration, various species of toxic and environment-damaging atoms (such as
lead), molecules (e.g. DDT), and mixtures (garbage and some air pollutants,
among others) are marshaled, go through series of physical states and
situations, interact with structures and systems of various characteristics,
and produce damage in sequences leading to the final, stable results.
Similar comments can be made concerning the ecology
of some of the viral, unicellular, and metazoan organisms that attack animate
and inanimate structures; their hosts; and the types and stages of damage they
produce.*
Sufficient differences among systems often exist,
however—for example, the ecology of the agents of many anthropod-borne diseases
in quite complex, and the life cycles of organisms such as schistosomes require
two or more different host species in sequence—to preclude at this time many
generalizations useful across the breadth of all environmental hazards and
their damaging interactions with other organisms and structures.
It has not generally been customary for individuals
and organizations that influence, or are influenced by damage use to harmful
transfers of energy to analyze systematically their options for loss reduction,
the mix of strategies and tactics they might employ, and their cost. Yet, it is entirely feasible and not
especially difficult to do so, although specific supporting data are still
often lacking. In fact, unless such systematic
analysis is done routinely and well, it is generally impossible to maximize the
pay-offs both of loss-reduction planning and of resource allocations.
Such analysis is also needed to consider properly
the problems inherent in the use of given strategies in specific
situations. Different strategies to
accomplish the same end commonly have different requirements; in kinds and
numbers of people, in material resources, in capital investments, and in public
and professional education, among others.
In the case of some damage reduction problems, particular strategies may
require political and legislative action more than others. And, where the potential or actual hazard
exists across national boundaries, correspondingly international action is
commonly essential.
The types of concepts outlined in this note are
basic to dealing with important aspects of the quality of life, and all of the
professions concerned with the environment and with the public health need to
understand and apply the principles involved—and not in the haphazard, spotty,
and poorly conceptualized fashion now virtually universal. It is the purpose of this brief note to
introduce the pathway along which this can be achieved.
W. Haddon, Jr., “The Changing Approach to the
Epidemiology, Prevention, and Amelioration of Trauma: the Transition to
Approaches Etiologically Rather Than Descriptively Based.” American Journal of Public
Health, 58 1431-1438, 1968.
W. Haddon, Jr., “The Prevention of Accidents,” in
Textbook of Preventive Medicine, ed. D.W. Clark and B. MacMahon (
W. Haddon, Jr., E.A.
Suchman, and D. Klein. Accident Research, Methods and Approaches, Harper and Row, 1964.
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