ENVIRONMENTAL HEALTH SERIES
Air Pollution
SEMINAR
ON HUMAN
BIOMETEOROLOGY
S. DEPARTMENT OF HEALTH
EDUCATION, AND WELFARE
Public Health Service
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SEMINAR
ON HUMAN BIOMETEOROLOGY
Sponsored by
National Center for Air Pollution Control
and.
Environmental Science Services Administration
*
January. 14-17, 1964
Cincinnati, Ohio
U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Bureau of Disease Prevention and Environmental Control
National Center for Air Pollution Control
1967
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The ENVIRONMENTAL HEALTH SERIES of reports was estab-
lished to report the results of scientific and engineering studies of
man's environment: The community, whether urban, suburban, or
rural, where he lives, works, and plays; the air, water, and earth he
uses and re-uses; and the wastes he produces and must dispose of in
a way that preserves these natural resources. This SERIES of reports
provides for professional users a central source of information on the
intramural research activities of programs and Centers within the
Public Health Service, and on their cooperative activities with state
and local agencies, research institutions, and industrial organizations.
The general subject area of each report is indicated by the two letters
that appear in the publication number; the indicators are
AP — Air Pollution
AH — Arctic Health
EE — Environmental Engineering
FP — Food Protection
OH — Occupational Health
RH — Radiological Health
SW — Solid Wastes
WP — Water Supply and Pollution Control
Triplicate tear-out abstract cards are provided with reports in the
SERIES to facilitate information retrieval. Space is provided on the
cards for the user's accession number and additional key words.
Reports in the SERIES will be distributed to requesters, as sup-
plies permit. Requests should be directed to the Center identified
on the title page or to the Publications Office, Room 4112, Federal
Office Building, 550 Main Street, Cincinnati, Ohio 45202.
Public Health Service Publication No. 999-AP-25
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PREFACE
This seminar on biometeorology was intended for presentation to
a relatively small group. The Division of Air Pollution (National
Center for Air Pollution Control) and the Environmental Science
Services Administration arranged the seminar to introduce profes-
sional personnel of the Division to current biometeorological problems
and practices, particularly emphasizing the techniques that can be
applied in air pollution investigations.
The persons invited to speak are nationally and internationally
recognized authorities in their fields. Several were unable to attend
because severe weather immobilized air and rail transportation in many
areas across the nation. By rescheduling and substitution, the co-
moderators of the seminar, Mr. James Dicke and Dr. Robert J. M.
Horton, provided a cohesive program that evoked enthusiastic re-
sponse from the participants.
Because many of the attendees proposed that the material be
made available for more careful review and more widespread distribu-
tion, Mr. Dicke undertook the task of compiling the papers for publi-
cation. This volume is the result of his efforts.
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CONTENTS
Page
Abstract vii
Introduction to Human Biometeorology FREDERICK SARGENT II 1
Physiological Instrumentation DOUGLAS H. K. LEE 25
Climates of the United States MARK D. SHULMAN 43
Microclimatology A. VAUGHN HAVENS 61
The National Weather Records Center HAROLD L. CRUTCHER 73
Some Effects of Weather on Mortality PAUL H. KUTSCHEN-
REUTER 81
Heat Stress AUSTIN F. HENSCHEL 95
Effects of Ultraviolet Light on Man HAROLD F. BLUM 109
Hypoxia: High Altitudes Revisited D. BRUCE DILL 121
Indoor Climate JOSEPH AKERMAN 133
Air Ions and Human Health IGHO H. KORNBLUEH 145
Ecological Perspective in Biometeorology DAVID M. GATES 161
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ABSTRACT
This volume is a collection of papers presented at Cincinnati, Ohio,
January 14-17, 1964, at a seminar on human biometeorology. Sub-
jects discussed include physiological and climatological instrumenta-
tion, climates of the United States, altitude, microclimatology,
indoor and outdoor weather, ultraviolet light, heat exposure, air ions,
and ecology.
VII
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INTRODUCTION TO HUMAN BIOMETEOROLOGY:
ITS CONCEPTS AND PROBLEMS
Frederick Sargent, II, M.D.
Professor of Physiology
University of Illinois
Department of Physiology and Biophysics
Urbana, Illinois
SUMMARY
Human biometeorology studies that portion of the whole environ-
ment designated as the atmosphere, taking into account the cultural
environment of man; his adaptability to the atmosphere as evidenced
in the tanning reactions to ultraviolet radiation, in habituation to cold
and heat, and in acclimatization to heat, cold, and hypoxia; and his
modification of the atmosphere by controlling and by polluting it. By
adopting the ecological viewpoint and focusing attention on the broad
problems of phenotypic plasticity and genetic individuality, the bio-
meterologist can achieve a better understanding of the human or-
ganism-environment system and of man's capacity to manipulate his
environment to serve his future biological needs.
INTRODUCTION
The invitation to participate in this seminar on human biomete-
orology and to introduce the subject has stimulated me to begin a
task to which I have given much thought in recent years. I plan to
scrutinize human biometeorology, critically examine its working as-
sumptions, and delineate some of its major unsolved problems. I have
conducted biometeorological research for almost 30 years. I have
taught graduate students about biometeorology for more than a
decade. This experience has been combined with 7 years of intensive
and exciting work as chairman of a University Committee on Human
Ecology. It is against this background that I want to draw my
introductory sketch.
ECOLOGICAL PROPOSITIONS
ORGANISM-ENVIRONMENT, A SYSTEM
The organism and its environment constitute a system. The life
science that investigates this system is ecology. The environment of
ecology is really a concept, for that environment is a matrix of con-
ditions and circumstances, of spatio-temporal configurations, which
can be identified for analytical purposes as material or physical, biotic
or biological, and cultural or social. Biometeorology studies that por-
Sargent
-------
tion of the whole environment designated as the atmosphere, bince
biometeorology, in a sense, abstracts the organism from its total en-
vironment, a basic assumption underlies its investigations, viz. thab
non-atmospheric environmental influences are controlled 01 incon-
sequential. This assumption may be justified for biometeorological
studies of animals, but because human biology is not merely an ex-
tension of the principles of animal biology to man, the assumption,
insofar as man is concerned, is not valid.
NATURE OF HUMAN BIOMETEOROLOGY
The orientation and content of human biometeorology are differ-
ent from those of general biometeorology. From the strictly biological
viewpoint man possesses few characteristics that can be identified as
unique. To be sure, he can be distinguished morphologically. Func-
tionally, however, human beings differ from other animals more in
degree than in kind. We may then ask, what are the differences
between animals and man? Medawar(28) concludes that man is
unique among animals because culture has come to provide a con-
tinuum for many of those properties to which man owes his biological
fitness. Indeed, culture has become so much a part of man that it is
difficult to separate it from his biology (13). Thus it can be argued
that human biometeorology is distinctly different from general bio-
meteorology because of the very nature of human biology. It is dis-
tinctive because human biometeorology must be cognizant of the
cultural environment.
BIOLOGICAL FITNESS
Organisms demonstrate "biological fitness" if they are endowed
with organs, systems, and processes that enable them to sustain
themselves in and prevail over their environments (28). For man
there are inborn endowments and the technological creations of his
culture. Both have exhibited evolution, but cultural evolution has
been the more rapid (7). Both contribute to his biological fitness.
Medawar(28) views culture as "a biological instrument by means of
which human beings conserve, propagate, and enlarge upon those
properties to which they owe their present biological fitness and their
hope of becoming fitter still."
Biological fitness is greater among organisms that are adaptable
than among those that are adapted. Man is adaptable. His adapt-
ability arises from his genetic individuality, his phenotypic plasticity,
and his culture. This biological fitness must be measured against
man's total environment, not merely the atmospheric milieu (22).
Genetic Diversity
Each human being is a unique combination of genetic traits.
One individual is anatomically and functionally, with the exception
of monozygous twins, unlike any other(28). Paracelsus intuitively
appreciated, more than 400 years ago, the significance of this indi-
viduality. According to him, "man is constellated in himself might-
-------
ily" (33). This inborn diversity and the genetic system responsible
for maintaining that diversity allows selection to happen with the
result that evolution proceeds.
Phenotypic Plasticity
Phenotypic plasticity is the alteration in the individual with
change in the environment. The degree of plasticity is genetically
determined. It is the norm 'of reaction that the individual or the
species is capable of making to environmental change(12). To a large
extent the norm of reaction measures the sum total of selective en-
vironmental experiences that the species has survived during its
evolution. The norm of reaction, therefore, is past-oriented. Bio-
meteorological. expressions of phenotypic plasticity in the human
being are the tanning reaction to ultraviolet radiation, habituation
to cold and heat, and acclimatization to heat, cold, and hypoxia.
Culture
Culture constitutes the sum total of traditions and institutions
that man has created to regulate himself and the technology by which
he provides for himself and dominates the biota. By these means he
had brought under his control a large reserve of nutrient energy and
nutrient raw materials as domesticated plants and animals, and he
has extended his mechanical capabilities by the utilization of fossil
fuels and atomic energy. He has exhibited great capability of pro-
foundly modifying the atmospheric environment and its impact on
him. On the one hand, he has at his disposal numerous devices for
supporting and maintaining his health and comfort, e.g. medical tech-
nology, clothing, housing, heating and ventilating machinery, and
air-conditioning. On the other hand, particulate and gaseous dis-
charges from his technological establishments have polluted the
atmosphere of urban population centers and have damaged the biota.
The industrial atmosphere has become a constant threat to the health
of the laborer. Man's domesticated plants and animals demand the
use of insecticides and pesticides that are potential hazards to the
health of the plants, the animals, and man himself. The impact of
these cultural devices on man's continued biological fitness is a moot
point that demands the most careful ecological scrutiny. Since the
problems stemming from man's control of his atmospheric environ-
ment, indeed of his total environment, are complex and have multiple
causation, one must attack them on all fronts simultaneously; "in
fact," as Aldous Huxley (23) emphasizes, "nothing short of everything
is enough"."
MAN'S ADAPTABILITY AS PHENOTYPIC PLASTICITY
The starting point of human biometeorological theory is this con-
cept of biological fitness. The essence of man's fitness is his adapt-
ability; its main elements, genetic individuality, phenotypic plasticity,
" Reference 23, p. 63.
Sargent
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and culture, have been defined. Determining how each of these
elements contributes to biometeorological theory is our next t
Consider phenotypic plasticity first.
From the biological viewpoint man is a regulator (35). A regu a-
tor maintains, despite external environmental vicissitudes, a stea y
state among the physicochemical properties of its internal environ-
ment. This internal environment is aqueous; it is the fluid w^icn
bathes the cells, tissues, and organs. The steady state is called
homeostasis. Basically the steady state is a state of limited variability
of the properties of the internal environment. The limitation of the
variability is accomplished by regulatory processes or homeostatic
mechanisms. Because the organism is an open system that derives
nutrient energy and nutrient raw materials essential for its continued-
existence from its external environment, one can conceive of homeo-
static mechanisms as comprising both internal and external regula-
tions. For example, the control of blood sugar comprises equally the
internal regulation of the neuroendocrine system and the external
regulatory behavior of searching for sources of nutrient energy. To-
gether such internal and external processes permit organismic self-
regulation.
The limitation of variability of the internal environment depends
upon the effective operation of homeostatic mechanisms. In turn,
however, the effective operation of these mechanisms requires that
the internal environment exhibit some variation. The organisms
possess sense organs, which detect alterations in their surroundings.
The changes are deviations from set points. As a consequence of the
detection of deviation, reactions, both physiological and behavioral,
are set in motion to correct the deviation. The deviation is never
corrected completely. There is constant variation about the set point.
This variation constitutes an inherent variability of the organism that
might be designated as system variability.
PRECISION OF REGULATION
The limits within which the physicochemical properties of the
internal environment vary is a function of the precision of physio-
logical regulations. The variability that characterizes the steady state
is both hierarchical and lawful. It is hierarchical because there is a
rank-ordering of the precision with which the properties are regu-
lated. It is lawful because the variation of the physicochemical prop-
erties exhibits distinctive circadian, menstrual, and seasonal rhythms;
the variation is not random.
The precision of physiological regulation may be measured in
terms of inter-individual variability. There is demonstrable a hier-
archy of preciseness with which the chemical composition of the blood
is regulated (41). Certain constituents of the blood particularly es-
sential for the normal functioning of the body cells, for example
osmolarity, pH, sodium, and potassium (Figure 1), are precisely
regulated or closely guarded. Other constituents not so essential for
the normal functioning of the body are less closely guarded. In this
HUMAN BIOMETEOROLOGY
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category one finds intermediary metabolic substances such as glucose
and cholesterol and metabolic waste products (Figure 1). Further-
more, the homeostatic processes that regulate the composition of the
blood, for example functioning of the lungs and kidneys (Figure 2),
are more variable than the properties of the blood (41). The regula-
tory processes show more variance than do the properties regulated.
These hierarchies of inter-individual variability apply equally to
intra-individual variability, even though a single individual generally
exhibits much less variation than does a group of individuals (41).
VARIABILITY OF CHEMICAL PROPERTIES OF INTERNAL
ENVIRONMENT (Fi,gd Nutrient Rtglmfn)
2.2
2.2
2.6
6.2
6.5
8.8
10.0
11.5
13.0
13.5
19.2
203
29.2
26.6
33.9
42.1
42.9
-
|
SODIUM
CHLORIDE
OSMOLARITY
HEMATOCRIT
CALCIUM
POTASSIUM
N. P. N.
GLUCOSE
INOR6. PHOSPHATE
CREATININE
UREA
CHOLINESTERASE
LEUCOCYTES
CHOLESTEROL
KETONE BODIES
ALK. PHOSPHATASE
AMYLASE
— 1 . 1
10 20 30 40
COEFFICIENT OF VARIATION
50
Figure 1 — Hierarchy of precision of regulation of chemical composition of man's internal
environment. (Reference 41. Reproduced with permission of McGraw-Hill Co.)
Season and Precision of Regulation
The season of the year when measurements are made of the
physicochemical properties of the internal environment and of the
regulatory processes does not alter the hierarchy of precision of
regulation, but season does markedly influence the degree of pre-
cision (Figure 3). The chemical properties of the blood exhibit
Sargent
-------
appreciably greater inter-individual variability in winter -rJrereas
the physical properties, such as temperature and blood pressure, and
the functioning of the homeostatic mechanisms show muen greater
inter-individual variability in summer. These facts suggest tnac me
winter season may have a particular impact on bodily metabolic
processes, whereas the summer season may have an especial impact
on the physiological functions of major organs and systems such as
thermoregulation, renal function, and the cardiovascular system.
Although the full meaning of this seasonal influence is not immedi-
ately apparent, a more detailed consideration of the Impact of season
on man will be presented after the concept of effectiveness of regula-
tion has been described,
HIERARCHY OF PHYSIOLOGICAL VARIABILITY
50-i
40-
30-
20-
10-
0 -
60-
EO-
N
1
„«
_
INTERNAL ENVIRONMENT
CHEMICAL PROPERTIES
i
hih
INTERNAL ENVIRONMENT
PHYSICAL PROPERTIES
\
JO-)
:i
^
1
—
H FiXED WET
Q REGULAR Dfl
tin
40 J
OftCAK FUNCT.'Otl
Figure 2 —
of mter-'ndiVfduaS variability, (Reference 4K
pei-misjion of McGraw-Hill Co.)
EFFECTIVENESS OF PHYSIOLOGICAL REGULATION
Effectiveness cf physiological regulation may be measured by
the capability of the organism to limit change when tr,,e p.nviron'
mental circumstances are altered. The ability to maints.ii-.. the rhem"
HUMAN
-------
SEASON AND ORGANISMIC
VARIABILITY
A FIXED DIET
o REGULAR DIET
Physical
) — of Internal Environment
' 0 10 20 3O 50 60 70 0 10 20 30 40 50 60 70
SUMMER
J i
figure 3 — Season and inter-individual variability among young men on fixed and regular
diets. Summer and winter compared for chemical and physical properties of internal
environment and for functioning of organs and systems. Lin>2 at 45° is lino of no seasonal
effect.
ical properties of the blood and the body temperature in the face of
external environmental change is a function of the adaptability of
the organism. Effectiveness and precision of regulation are closely
related (42). When human beings are abruptly exposed to under-
nutrition, unaccustomed diets, and restricted allowances of water, the
properties of the blood that are most closely guarded change least;
those least precisely regulated change most (Figure 4).
Effectiveness of physiological regulation appears to be hierarchi-
cal. The evidence for this thought conies from investigations of the
physiology of sweating. When a dehydrated man is exposed to a hot
atmosphere in which thermoregulation is mainly achieved through
sweating, continued sweating will accentuate dehydration. With
increasing dehydration maintenance of body temperature is disturbed.
Will s«veat loss, at this point, decline so as to conserve body water?
With severe dehydration, the decrement of sweating is physiologically
inconsequential(2, 37, 42). The organismic "decision" is to maintain
heat loss at the expense of body water. Thus, thermoregulation seems
to be dominant over processes of water regulation. Its dominance
creates a vicious circle that will be fatal if external regulation cannot
be achieved.
Sargent
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EFFECTIVENESS OF PHYSIOLOGICAL REGULATION
SODIUM
CHLORIDE
OSMOLARITY
HEMATOCRIT
CALCIUM
POTASSIUM
NONPROTEIN NITROGEN
GLUCOSE
INORGANIC PHOSPHATE
CREATININE
UREA NITROGEN
CHOLINESTERASE
LEUCOCYTES
CHOLESTEROL
KETONE BODIES
ALKALINE PHOSPHATASE
AUYLASE
??
??
?6
6.2
6.5
8.8
10.0
11.5
13.0
13.5
19.?
703
24.2
26.6
33.9
42.1
42.9
Inter-Individual i
Variability f
£
JZ
ri
i
i
i
i
i
i
i
i
i • i
40 20 C
i Nutritionally Induce,;
1 Variability
i
n
j
1 .
i _
j
i
i
i
i
0.5
2.4
1.8
3.4
2.9
3.0
11.6
17.7
4.4
?8.7
•ifi
11 1
14.?
7?
I I IfiB.q
I
1
33.3
6.0
20 40 150
Percent
Figure 4 — Comparison between precision and effectiveness of physiological regulation of
chemical properties of internal environment. Rank-order correlation coefficient +0-78.
(Reference 42.)
Season and Effectiveness of Physiological Regulation
The fact that inter-individual variability in the chemical prop-
erties of the blood is greater in winter than in summer suggests an
inherent metabolic instability at this season. When the nutritional
condition is abruptly altered—the diet is changed from a customary
one to an unaccustomed one consisting of insufficient nutrient energy,
unusual amounts of protein, carbohydrate, and fat, and restricted
water—the effectiveness of the physiological regulation is critically
taxed. If such a nutritional stress is imposed in both winter and
summer, a distinctive metabolic syndrome becomes manifest in winter
but not in summer (Figure 5). In winter there is hypoglycemia,
hyperketonuria, azotemia, and symptoms consistent with hypogly-
cemia. The syndrome is particularly marked among individuals on
regimens high in fat. In summer these biochemical changes and
symptoms are absent (42).
In summer, the inter-individual variability of the physical prop-
erties of the blood and of organ functions is greater than in winter.
When these same nutritional stresses are abruptly imposed on sub-
jects in summer, disturbances of thermoregulation and cardiovascular
function appear. There is hypohidrosis, anhidrosis, hyperventilation
tetany, orthostatic hypotension, and heat exhaustion. The clinical
disturbances are more common among dehydrated than adequately
hydrated individuals (39, 40). Comparable alterations of diet do not
elicit these disturbances in the winter. Effectiveness of water con-
servation is a most important adaptive reaction in summer. The
summer syndromes are thus not so unexpected and problematical as
the winter syndromes.
HUMAN BIOMETEOROLQC4Y
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.Experimental Subject
WINTER
O—-QControl Subject
SUMMER
^
2.8
a.o
"
i.o
0.5
80
so
40
Ketone Bodies
J L
301*
26
N.P.N
Urea Nitrogen
Creotinine
22
18
14
Expert—
mental
Regimens
32
si i
WEEKS
Figure 5 — Influence of season on metabolic reaction of young men to change of nutrient
regimen. (Reference 42.)
Sargent
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TEMPORAL VARIABILITY, A FUNDAMENTAL PROBLEM
HUMAN BIOLOGY
Our general ecological proposition is that man and his f
ment constitute a system. Both "man" and "environment
temporal variability. For each, two rhythms are distinctive: one
runs its course in 24 hours; the other is seasonal. For tne organism
the 24-hour rhythm has been identified as circadian (15). Both rhythms
have been demonstrated at all levels of biological organization (14, 48).
They appear to be fundamental characteristics of lite. Twenty-tour
hour and seasonal rhythms are moreover as characteristic of the
cosmic terrestrial environment as they are of life processes. Two
deductions have been made from these parallel rhythms. First,
biologists have subscribed to a causal relation between the environ-
mental events and the biological (3, 8, 11, 17, 44, 48, 49). Second, the
existence of these rhythms has led to the speculation that an exoge-
nous biological clock times life processes(49, 59),
I suggest that these biological rhythms are actually an expression
cf the adaptive plasticity of living organisms to the restrictions im-
posed on them during their evolution in the cosmic-terrestrial en-
vironment. This hypothesis is realty an extension of L, J. Henderson's
concept of fitness of the environment. According to this concept,
"The fitness of the environment is one part of a reciprocal rela-
tionship of which the fitness of the organism is the other. This
relationship is completely and perfectly reciprocal; the one
fitness is not less important than the other nor less invariably a
constituent of a particular case of biological fitness , ."a
"The properties of matter and the course of cosmic evolution are
. . intimately related to the structure of the living being and to
its activities; they become, therefore, far more important in
biology than has been previously suspected. For the whole evo-
lutionary process, both cosmic and organic, is one, and the biolo-
gist may now rightly regard the universe in its very essence as
biocentric."'3
When one attempts to deal logically with either Henderson's
concept of fitness or the parallel rhythmicity of organism and environ-
ment, an identical problem arises, namely the problem of circular
reasoning. As Blum(8) states it, ". . . fitness partakes of the nature
of uniqueness, and this uniqueness of the earth as an abode of life is
a matter that strikes one more forcibly the more he tries to break
out of the circle."0 Perhaps one of the most basic implications of
space technology is the opportunity ic gives the biologist to break out
of the circle. If the temporal-spatial configurations of the cosmic-
terrestrial relations of living organisms sets the clock that times tb«=>
•'Henderson (1913), p, 271 (Reference 19),
^ Henderson (1913), p, 312 (Reference 19).
" Blum (1962), p. 73 (Reference 6).
HUMAN BIOMETEOKQI,5>
-------
functioning of their cells, tissues, and organs, a major reorientation of
the time-space relationships of the organisms should seriously disrupt
the functioning of the organism.
EVIDENCE OF ADAPTIVE NATURE OF TEMPORAL VARIABILITY
Health may be viewed as a state in which the physiological
regulations are operating most effectively. In this state the organ-
ism's integrative functions are harmoniously blended so that the
individual can meet and cope with his environmental challenges (14,
18). With dysfunction or ineffectiveness of physiological regulation,
disease occurs(14, 20). The conclusion has been reached that circa-
dian and seasonal variation in the precision and effectiveness of
physiological regulation is a manifestation of adaptive plasticity of
the organism. This conclusion is consistent with the prevalent view
that circadian and seasonal variations are "physiological."
Numerous observations support the view that these rhythms are
adaptive reactions to the external atmospheric environment. A few
examples will illustrate my point. The seasonal rhythms in man may
be viewed as acclimatization to heat in the summer and cold, in the
winter(54). In summer people are comfortable at higher tempera-
tures than in winter. In summer the sweating mechanism is more
reactive than in winter—the latent period for induction of sweating
is short and for a given stimulus the output of sweat is greater (25).
In winter a longer period is required to induce shivering than in the
summer (10). In summer the output of urinary antidiuretic hormone
is greater than in winter (54), The summer tanning reaction and the
thickening of the stratum corneum protect against the damaging in-
fluences of ultraviolet radiation(5).
TEMPORAL VARIABILITY CF DISEASE
If circadian and seasonal rhythms are indeed expressions of
adaptive plasticity, why then does human disease show circadian snd
seasonal variation? Death., for example, comes to man more often
in the early morning hours than at other times, and most diseases
display clear seasonal variations in morbidity, prevalence, and mor-
tality. These facts suggest that man's susceptibility to disease is
different at different phases of the circadian and seasonal rhythms.
Tetany and rickets, for example, are most prevalent in the spring.
At this season the healthy population shows low blood calcium and
phosphate and high alkaline phosphatase, negative calcium balance.,
and maximal sensitivity to galvanic stimulation(24, 36). These "phys-
iological" alterations constitute a formes frustes of tfte clinical disease.
Some 10 years ago I advanced the hypothesis (36) that there are dif-
ferent degrees cf effectiveness of physiological regulation within the
population. Some people exhibit only the biochemical and functional
alterations; others, whose regulation is less effective, develop dys-
function and clinical symptoms. Now I am convinced that the expla-
nation is more complex, for the following additional elements must
Sargent
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be taken into account: (1) the environmental conditions for which
adaptive plasticity evolved, (2) the age-structure of the population,
and (3) physiological individuality. At the present time just a
glimmering of the basic significance of these factors is emerging.
Evolution of Adaptive Plasticity
The norm of reaction or the adaptive plasticity of an individual
or a population is a function of the genotype. The adaptive potential
of a genotype depends upon the past experience of the species(12)
Selective screening, in other words, is past-oriented. For man and
other primates, indeed for mammals generally, this selection has been
stabilizing, for it gave rise to homeostasis. Since the adaptive poten-
tial is past-oriented, adaptiveness that has been adequate for former
generations will not necessarily be adequate for future generations,
particularly if those generations create environments that are beyond
the norm of reaction of the genotype.
Health is sustained by preserving the adaptive capacity. Adaptive
capacity is maintained by repeated environmental challenge from
such forces as the organism prevailed over in its evolution, viz.,
weather and climatic change, scarcity of food and water, predation,
and disease(45, 46). Man's present biological fitness, however, also
depends upon cultural tradition and cultural innovation. Increasingly
he lives, works, and plays in a constant physical environment regu-
lated technologically so that he is comfortable all the time. This
cultural innovation which began with the discovery of fire, has in-
creasingly come, as Dubos(14) expresses it, "to place him outside the
order of things."a The fundamental problem for human biometeorol-
ogy cannot be better stated than in the words of Dubos(14). "By
changing the physical world to fit his requirements—or wishes—he
has almost done away with need for biological adaptation on his part.
He has thus established a biological precedent and is tempting fate,
for biological fitness achieved through evolutionary adaptation has
been so far the most dependable touchstone of permanent success in
the living world. "a
None would gainsay that man has become a significant ecological
factor. He has rapidly molded the total environment to suit his own
wishes. Has he, at the same time, modified the environment in con-
formity with his biological needs? Cultural evolution has been so
rapid—exponential, in fact—that it is valid to question whether man
has not overstressed his adaptive plasticity. As Dubos(I4) states it,
"The one characteristic of our civilization is the rapidity with which
it changes all our ways of life, without too much, if any, concern
for the long-term effects of these changes. Man can eventually be-
come adapted to almost anything, but adaptation demands more time
than is allowed by the increasing tempo at which changes are pres-
ently taking place."b
" Reference 14, p. 49.
b Reference 14, p. 140.
12 HUMAN BIOMETEOROLOGY
-------
To answer these questions one must be able to piece together the
conditions and circumstances for which man exhibits adaptiveness.
Perhaps the fact that man exhibits seasonal disease results from his
living outside his adaptive capacity at certain seasons, living at these
seasons under conditions that are widely divergent from those that
the basic organismic reactions expect (21).
The Life Sequence and Seasonal Disease
There is an intriguing interaction among culture, adaptive capa-
city, and season, which expresses itself in the seasonal variation of
disease at different stages of the life sequence. This interaction pro-
vides some clues regarding the problem of season and disease.
There is an ontogeny of physiological regulations (1). Pre-
cision and effectiveness of regulation mature and decay during the
life sequence. The newborn exhibits immaturity of physiological
regulation. During the reproductive period adaptive capacity is
maximal. After this time, as aging begins, precision and effective-
ness of regulation are reduced (43). During the stages when the
homeostatic mechanisms are maturing and again when they exhibit
deterioration, mortality from all disease varies seasonally (26). Both
in the young and the old, moreover, mortality is maximal in winter
(Figure 6). When the homeostatic processes exhibit maximal pre-
cision and effectiveness, the total mortality shows no seasonal varia-
tion. Comparable findings have been reported by Panhorst(34) for
mortality from diabetes mellitus. These striking observations suggest
that age must be taken into account to arrive at a clear understanding
of the nature of season and disease.
Momiyama(30, 31, 32) has found that during the past 50 years
the mortality among Western cultures has become increasingly re-
stricted to the winter months (Figure 7). Diseases with a formerly
characteristic peak in summer, e.g. gastrointestinal disease and beri-
beri, now show a winter maximum. For winter diseases, particularly
cardiovascular and degenerative disease, the mortality of that season
has shown a relative accentuation (Figure 8). These changing pat-
terns of disease have coincided with two phenomena of advancing
civilization: cultural innovation in the form of medical and sanitary
technology, and aging of the population.
Why winter should become a season of maximum mortality with
advance of culture is not at all clear from the facts now in hand.
Perhaps a few speculations might be offered to stimulate thought on
this intriguing problem. First, we might view senescence as an acci-
dental byproduct of evolution — a byproduct of an adaptation that
had survival value for the organism and the species during infancy
and childhood(45, 46). Second, man is physiologically(27) and eco-
logically (4) a tropical animal. Man's migration into cold climates
from the original tropical niche was made possible by cultural inno-
vation. The norm of reaction of modern man still carries this trop-
ical bias. With senescence, effectiveness of regulation deteriorates (43,
50). Some adaptive capacity for heat remains; capability of dealing
Sargent 13
-------
with the winter season rapidly declines. The consequence is an in-
creasing winter mortality as continued cultural innovation becomes
increasingly capable of supporting an aging population.
MONTH
LU
i.
>-fi FIII i i "i ii 1-1 i
/^\^_/t^r"^_j
!/ \"v \ ^y '
^-N, '•/,-•'
19^9-1958 DATA
-------
individualizing way, to fit each separate functional effect into
its proper place in the adaptation process at large. It is conceiv-
able that individuals may not be all alike in their choice of the
acclimatization mechanisms which nature has placed at their
disposal. Some may succeed in striking the medium road, pre-
(a)
1930-1934
(c) 1952-1956
Figure 7 — Calendars ef seasonal diseases in metropolitan Toky-3> far three periods 1912-
1916, 1930-1934, and T952-1956. (Keference *?.)
Sargeat
-------
ferring to divide up the burden imposed by a trying environment
on several functions without unduly taxing any o>ie of them.
In such cases it may be difficult by our as yet imperfect methods
to detect any measurable deviation from accepted standards. On
the other hand it appears to be fairly well established that others
may exhibit abnormalities as a consequence of their failure to
equilibrize the acclimatization process."
2500
2000
1600
600
2 3 4 5 G 7 8 9 id 11 I?
MONTH
Figure 8 — Seasonal variation in total death rate for Japan for various years from 1900-
1955. (Reference 32.)
BIOCHEMICAL INDIVIDUALITY
Within the relatively narrow limits of the steady state denned
earlier, there is a distinctive biochemical individuality (42, 51). When
a variety of biochemical measurements is made repeatedly under
standardized conditions, each individual in the group under study
exhibits a unique pattern of mean values (Figure 9). The hierarchy
of the precision of regulation is imposed on these patterns. Biochem-
ical individuality is more evident among the properties that are less
closely guarded than among the properties that are precisely regu-
lated.
PHYSIOLOGICAL INDIVIDUALITY
Physiological individuality may be shown in two ways: in pat-
terns of mean values of organ function measured under standard
conditions and in patterns of physiological response to stressful con-
16
HUMAN BIOMETEOKOLOGY
-------
SUBJECTS ON REGULAR DIET: WINTER
Piacl ^1
93C1 9 • 7
94C
95C
96C »
Figure 9 — Individual patterns of chemical properties of infernal environment. Circles
represent group mean for each chemical property measured. Radial t'jnes represent indi-
vidual mean values for each chemical property measured. Chemical properties measured were
serum osmolarity (1), serum sodium (2), serum potassium (3), serum total calcium (4), serum
chloride (5), serum inorganic phosphate (6}f serum nonprotein nitrogen (7), serum creatinine
(8), whole blood glucose (9), serum total cholesterol (10), serum total ketone bodies (11),
serum cholinesterase (12), serum amylase (13), serum alkaline phosphatase (14), whole blood
hematocrit (15), and whole blood total leucocyte count (16). (Reference 42.)
ditions. When the mean values of a variety of organ functions are
calculated from six separate tests on the same 12 fit young men shown
in Figure 9, unique patterns again emerge (Figure 10). The level at
which the temperature and blood pressure are maintained and the
tempo at which homeostatic mechanisms operate is a distinctive char-
acteristic of the individual.
Eight other fit young men marched 6 hours in an hot, moist en-
vironment on four or five occasions. The walks were spaced at
intervals of 2 to 3 weeks so that acclimatization would not develop.
During the walks the thermoregulatory and cardiovascular responses
were measured. When the mean and extreme values of these meas-
urements were assembled graphically, it was found that each man
reacted to the march in moist heat in a reproducible and characteristic
manner.
Sargent
17
-------
SUBJECTS ON REGULAR DIET: WINTER
Figure 10 — Individual patterns of organ function. Circles and radial lines calculated as
described for Figure 9. Organ functions represented are reclining systolic blood pressure (1),
reclining diastolic blood pressure (2), reclining pulse pressure (3), reclining pulse rate (4),
minute urinary volume (5), creafinine clearance (6), osmotic clearance (7), urinary pH (8),
urinary timetable acidity (9), pulmonary ventilation (10) and estimate of passage of time:
20 seconds (11), 45 seconds (12) and 70 seconds (13).
Figure II illustrates the thermoregulatory reactions. Note that
in most cases, the extreme values closely parallel the means. Under
the standardized conditions of these experiments, these men re-
sponded to the heat in eight distinct ways.
Figure 12 demonstrates a comparable individuality for the cardio-
vascular reaction to work in heat. These two charts amply confirm
the wisdom of Sundstroem's remarks quoted above.
EVIDENCE OF GENETIC ORIGIN OF BIOCHEMICAL AND
PHYSIOLOGICAL INDIVIDUALITY
These patterns of individuality may be genetic in origin. The
genotype of an individual probably determines not only his pattern
of mean values of biochemical and physiological measurements but
also the norms of reaction to environmental change. For instance,
naonozygous twins exhibit less individuality in biochemical and
physiological measurements than do unrelated persons (52). Within
large populations individuals can be found whose measurements
deviate by more than three standard deviations from the population
mean. These deviations are disconformities(53). There is ample evi-
dence that many disconformities are genetic. Much additional re-
search on human biology will have to be undertaken, however, to
demonstrate whether patterns of individuality characteristic of most
persons are also genetic.
18
HUMAN BIOMETEOROLOGY
-------
0505
TIME, hr
Figure 11 — Individual patterns of thermoregulatory response by eight men to marching 5.6
km/hr at 37 °C corrected effective temperature. Heavy central lines represent mean hourly
values of rectal temperature, mid-thigh skin temperature, and total body-sweat rate, light
llines represent range of individual hourly observations.
Figure 12 — Individual patterns of cardiovascular reaction to marching 5.6 km/hr at 31 °C
corrected effective temperature. Deviations from resting (control) observations of blood
pressure and pulse rate represented in same fashion as described for Figure 11.
Sargent
19
-------
SUMMATION
The primary object of study by the human biologist is the system
composed of the organism and a matrix of environments. Tire two
elements of the system are inseparable. The organism of itselt is an
open system with needs for specific forms of matter and information.
The organism functions to maintain in equilibrium a number of
variables in different subsystems of its total self (29). The environ-
ment is equally complex; it is comprised of the material, biotic, and
cultural components. This system, in spite of its great complexity,
must be investigated holistically if deep understanding is to be
realized. This viewpoint does not gainsay the specialized study of
limited aspects of this system; the productivity of the biological
sciences attests to the value of such study. My point is that the discrete
bits of information contributed by the specialists must finally be
fitted into the broad picture to arrive at a general knowledge of the
system. The human biological scientist must ever think in terms of
multiple causation of the processes he studies. He must relate to the
more general concept of the system with which he deals.
Human biometeorology specifically must focus its attention on
the broad problems of phenotypic plasticity and genetic individuality.
Human biometeorology must adopt the ecological viewpoint as it in-
vestigates man and his atmospheric environment. Only by this
approach can the human biometeorologist ever achieve an under-
standing of the organism-environment system and fully appreciate
the implications of man's capacity to manipulate his environment for
his future biological fitness.
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Ed. Springer, Berlin. 1952.
12. Dobzhansky, T. Evolution, Genetics, and Man. John Wiley & Sons,
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N. Y. 1961.
15. Halberg, F. Physiologic 24-hour periodicity; general and procedural
considerations with reference to the adrenal cycle. Zeitschr. f. Vita-
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20. Hinkle, L. E., Jr. and Wolff, H. G. The nature of man's adaptation to
his total environment and the relation of this to illness. A.M.A. Arch.
Int. Med., 99:442-460. 1957.
21. Hughes, E. Seasonal Variation in Man. H. K. Lewis, London. 1931.
22. Hulse, F. S. Adaptation, selection, and plasticity in on-going human
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23. Huxley, A. Human potentialities. In Man and Civilization. Control of
the Mind. (S. M. Farber and R. H. L. Wilson, eds.) McGraw-Hill,
N. Y., pp. 60-76. 1961.
24. Iwanami, M., Osiba, S., Yamada, T., and Yoshimura, H. Seasonal
variations in serum inorganic phosphate and calcium with special
reference to parathyroid activity, J. Physiology, 149:23-33. 1959.
25. Kuno, Y. Human Perspiration. C. C. Thomas, Springfield. 1956.
26. Kutschenreuter, P. H. A study of the effect of weather on mortality.
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27. Lee, D. H. K. Physiology as a guide to combatting tropical stress.
New Eng. J. Med., 243:723-730. 1950.
28. Medawar, P. B. The Uniqueness of the Individual. Methuen & Co.,
Ltd., London. 1957.
29. Miller, J. G. The individual response to drugs. In Man and Civiliza-
tion. Control of the Mind. (S. M. Farber and R. H. L. Wilson, eds.)
McGraw-Hill, N. Y., pp. 92-109. 1961.
30. Momiyama, M. The geographical study of "seasonal diseases". (I).
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Japan. Ser. II, 38:47-60. 1960.
31. Momiyama, M. The geographical study of "seasonal diseases". (II).
Calendars of "seasonal diseases" in the world. J. Meteorol. Soc. Japan,
Ser. II, 39: 103-115. 1961.
32. Momiyama, M. High winter mortality of "seasonal diseases". Papers
in Meteorol. and Geophys., 12:163-178. 1961.
Sargent 21
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33. Pachter, H. M. Paracelsus: Magic into Science, Collier Books (A570),
N. Y. 1961.
34 Pannhorst, R., and Rieger, A. Manifestierung des Diabetes und Jahres-
zeit. Ztschr. f. Klin. Med., 134:154-160. 1938.
35. Prosser, C. L. Perspectives of adaptation: theoretical aspects. In
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(D. B. Dill, ed.) Am. Physiol. Soc., Washington, D. C., pp. 11-25. 1964.
36. Sargent, F., II. A critique of homeostasis: season and metabolism.
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37. Sargent, F., II. Depression of sweating in man: so-called "sweat gland
fatigue". In Advances in Biology of Skin Vol. III. Eccrine Sweat
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Silver (eds.). Pergamon Press, London, pp. 163-212. 1962.
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K. P. Observations on dehydration and eccrine sweating. Proc. Unesco
Symposium on Physiology and Psychology of Man in Arid Conditions,
Lucknow, India. Arid Zone Research, 24:115-119. 1964.
39. Sargent, F., II, and Johnson, R. E. Observations on experimental
anhidrosis. Lancet, 1:1018-1021. 1960.
40. Sargent, F., II, Sargent, V. W., and Johnson, R. E. The Physiological
Basis for Various Constituents in Survival Rations. Part III. The
Efficiency of Young Men Under Conditions of Moist Heat. WADC
Technical Report 53-484, Part III, Vols. I and II. Wright Air Develop-
ment Center, Dayton, Ohio. 1957-1958.
41. Sargent, F., II, and Weinman, K. P. Variabilite physiologique chez
rhomme jeune. Biotypologie, 23:137-171. 1962, Also in Physiological
Measurements of Metabolic Functions. (C. F. Consolazio, R. E. John-
son, and C. S. Pecora) McGraw-Hill, N. Y., pp. 453-480. 1963.
42. Sargent, F., II, and Weinman, K. P. Effectiveness of physiological
regulation. Nishin Igaku (Japan), 50-327-339. 1963b. Also in Bio-
typologie, 25:18-48. 1964.
43. Shock, N. W. Some of the facts of aging. In Aging . , . Some Social
and Biological Aspects. A.A.A.S. Symp. No. 65, Washington, D. C.,
pp. 241-260. 1960.
44. Sollberger, A, Significance of biological rhythm study for human
biometeorology. Inter. J. Biometeorol., 7:193-220. 1963.
45. Strehler, B. L. Dynamic theories of aging. In Aging . . . Some Social
and Biological Aspects. A.A.A.S., Washington, D. C., pp. 273-303. 1960.
46. Strehler, B. L. Time, Cells, and Aging. Academic Press, Inc., N, Y. 1962.
47. Sundstroem, E. S. The physiological effects of tropical climate, Phys-
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48. Tromp, S. W. Medical Biometeorology. Weather Climate and the Living
Organism. Elsevier Publ. Co., Amsterdam. 1963.
49. Webb, H. M., and Brown, F. A., Jr. Timing long-cycle physiological
rhythms, Physiol. Rev. 39:127-161. 1959.
50. Williams, G. C. Pleiotropy, natural selection, and the evolution of
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22
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52. Williams, R. J. Chemical anthropology—an open door. Am. Scientist,
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8:165-178. 1958.
Sargent 23
GPO 801—494—2
-------
PHYSIOLOGICAL INSTRUMENTATION
Dr. Douglas H. K. Lee*
Activity Assistant Chief for Research, D.O.H.
U. S. Public Health Service
1014 Broadway
Cincinnati, Ohio 45202
SUMMARY
Physiology covers such a wide range of biological functions that
instrumentation required for one type of function cannot work for
another. Some of the difficulties encountered in biological instru-
mentation of man are due to the variability of biological material,
the unattainability of some sorts of data, the necessity of using
indexes instead of the measurement itself, the difficulty of standard-
ization, the variety of items for study, and the complexity of rela-
tionships of functions. For example, to measure skin temperature,
one can use thermocouples, thermistors, or radiometers. The various
methods of measuring other functions (such as sweat rate, oxygen
consumption, pulse rate, blood pressure, and distribution of water),
and a formula for quantitatively expressing man's relative strain are
given.
The assignment to speak on physiological instrumentation for
biometeorological studies is somewhat unusual for a physiologist.
Physiologists don't think in terms of a field of instrumentation as
peculiar to themselves. Physiology covers such a wide range of
biological functions that the types of instrumentation required for
one type of function or one set of circumstances just can't work for
others. I doubt that you will find any textbooks on physiological
instrumentation as I am sure you will on meteorological instrumen-
tation. Instead of trying to deal with this subject on a systematic
basis, I am going to stress principles underlying physiological meas-
urement — the kind of things that one aims at, the kind of difficulties
one gets into.
PROBLEMS — PRINCIPLES
Physiologists are a solemn lot. About the only amusement they
can get is when somebody who is trained in the so-called exact
sciences tries to apply the principles of measurements learned in the
exact sciences to biological material. Now biological material just
doesn't behave like most physical material and remain relatively
constant; it is extremely variable. It is very frustrating indeed for
somebody who is used to having his materials stay put to find that
this doesn't happen at all. Many other difficulties arise in physiological
*Now with the Division of Environmental Health Sciences, National
Institutes of Health.
Lee 25
-------
measurement, or biological measurement in general. One is that the
datum you want is very often completely unattainable. For example
I would very much like to have some method of estimating the net
strain developed in an individual when he is exposed to a certain
stressful situation. I don't know how to measure it; I even suspect
that it is virtually unmeasureable. It is a concept and not a thing
that can be measured; it is a very useful concept and one that we
would like to quantify.
Then again, one may wish to know something about a certain
function in the body, but getting an estimate or a measurement of
that function with a person still alive may be difficult. How would
you go about measuring the blood flow in the kidney of the person
sitting next to you and still leave him intact and functioning? So
many of the things you would dearly like to know just are not meas-
urable, and you must put up with a second or a third best. You take
some measurement that is only an index—an indication of what's
going on, and not the thing itself.
PULMONARY FUNCTION
Just now we are very much concerned with pulmonary function
and various measures of pulmonary function, particularly in relation
to dust diseases. Now there are all sorts of "pulmonary function
measurements," but these are really measurements of some aspect
of pulmonary function. For example, we measure the degree of
obstruction presented in the respiratory tree as the air goes in or
comes out; the extent to which some parts of the lung are shut off
and are not participating in the gaseous exchange; or some loss of
permeability in the membrane between the alveolus and the blood
stream. These are only special aspects of pulmonary function; they
are not pulmonary function itself. I like to think that the only
measure of pulmonary function would be a measurement of the
facility with which it gets oxygen across to the arterial blood in the
face of increasing demand. If you want to measure this, and if the
patient will let you, you can catheterize his right heart and his
arterial system, take samples of blood, and estimate the extent to
which oxygen is really getting through. But this is a somewhat
restricted procedure. You can't just haul in a coal miner, shove
catheters into his heart, and then send him back to work. The meas-
urement is possible under certain conditions but by no means under
all conditions. And yet we need measurements of pulmonary function.
How can we obtain them? Again, only by indirection and by some
sort of mental integration of the results obtained by different pro-
cedures.
A further difficulty is that with all biological material there is
the danger that what you are looking at becomes changed by your
process of looking. We are reminded of the Heisenberg Uncertainty
Principle, but in a different guise and a much wider sphere. One
hopes to find ways of looking at a biological system without dis-
turbing it.
26
HUMAN BIOMETEOROLOGY
-------
Further, the circumstances under which the observation is made
may exert far more influence on the result than the things you are
trying to study. For example, you may be measuring small differ-
ences in pulse rate as a response to a given situation or a given stress.
For a reasonably stable subject the change in pulse rate brought
about by relatively high temperatures is quite small in relation to
the change in pulse rate brought about by other things. Just the
prospect of being the subject of an examination or the fact that a
man is still mad at his mother-in-law may have much more effect
on his pulse rate than shoving the temperature up 15 or 20 degrees.
Again, you are frustrated in your attempts to measure the reaction,
unless, and this is a very important "unless", you can thoroughly
standardize your material.
STANDARDIZATION
Standardization is probably the most important single condition
for physiological measurement, but physiologists are not always cer-
tain how far they must go. Recently I attended a meeting, related
to a proposed International Biological Program; this meeting was to
set up the conditions for making comparable measurements in differ-
ent parts of the world on different groups of people. The recom-
mendations fell far short of requirements and omitted numerous
areas that need to be standardized. If the expert physiologists are
not fully aware of the needs, those who are not so experienced cer-
tainly will overlook this very important principle. Standardization
is probably the most important single principle for physiological
instrumentation.
SELECTION OF MATERIAL
Another major difficulty arises in selecting material for study.
Because so many variables are involved, it is virtually impossible to
obtain measurements on the total system. You cannot, in one life-
time, set up enough different experiments to take in all of the different
variable aspects of the system that will yield a complete line on the
total system. You must simplify. You say to yourself, "This very
limited number of variables I am going to study. The rest I am
hopefully going to hold constant and leave out of my further con-
sideration." This selection must be done consciously and not by
default. Unless the experimenter knows that these are the variables
he is going to standardize, he will find himself involved in purpose-
less arguments with others who are working in a similar field but
with a different selection of variables. In my work, for instance,
I may decide to standardize, and therefore ignore, the effect of nutri-
tion. The fellow next door may decide to make nutrition one of his
primary variables. We will never get together, and there is no point
in arguing about our results, since my results are comparable with
his at only one point. If you standardize your conditions and state
them clearly, your position will be obvious and argument will be
unnecessary.
Lee 27
-------
COMPLEXITY OF RESPONSE
The relationships between the response of the organism and the
stress that is applied to it are by no means simple functions. These
relationships are generally complex; very seldom do you find a
straight-line relationship, except over a very narrow range. For
example, if you measure the rectal temperature response to increas-
ing temperature, you will find at first no detectable change, then a
slight increase, and as the temperature goes up, a more and more
rapid increase in rectal temperature. You have a continually rising
but by no means linear function. If you measure something like sweat
rate, however, you will first get no sweat; then the sweat will increase
rapidly for a while, stay constant over the next phase of rising
temperature, and then taper off. Finally, if you insist on going further,
the sweat rate very probably will start to fall again. Here we have
anything but a simple function. Any extrapolation you made on the
first half of your curve as to what would probably happen on the
second half of the curve would be completely wrong. Unless you
have been over the ground and know what the function is likely to
be, you cannot extrapolate more than a very short distance from the
range that you have studied.
Furthermore, if you apply two stresses to a biological system—
first separately and then together—you do not get a simple additive
response. If, for example, you increase the air temperature and
measure the rise in pulse rate, you'll get a certain increment. If you
increase the work rate of the individual and measure the pulse rate,
you'll get a certain increment. If you expose the person to a high
temperature and give him work, the resulting increment in pulse rate
will bear no predictable relationship to the other two. There is no
rational basis for integrating these values. Again, unless you know
from experience, what the summation is likely to be, you have no
clues.
After one has accumulated enough data, perhaps, one could go
to a computer for assistance. But remember that the computer works
only with the data it is given. If the data are inadequate, or very
limited, then the computer will come up with some fancy answers
that won't mean anything. You'll still have to go back and find out
whether the computer was even in the ball park.
In Occupational Health we are plagued by our awareness that
the subject is only part of a very complex system—a family system,
a social system, an industrial system, an economic system, and so on.
The examination you want to make may be quite incompatible with
the system. We would very much like to have very extensive records
of changes in rectal temperature, core body temperature, skin tem-
perature, pulse rate, blood pressure, and so on, for a man doing his
work in a hot industry. Well, you can just imagine the reception
you would get if you went to the plant manager and said you wanted
to hitch up 79 cords to this man, with a whole truckload of equip-
ment trailing after him measuring all these things while he does some
complicated job. A measurement system may be technically feasible
28
HUMAN BIOMETEOROLOGY
-------
but totally impossible to carry out. When we want to measure the
man on his job, we must usually content ourselves with very simple
measurements that can be read without complex instrumentation.
These are some of the difficulties that one encounters in biological
instrumentation and particularly in the instrumentation of man.
MEASUREMENT OF HEAT
So much for the general principles. Now let me take one set of
circumstances by way of illustration and run through the kinds of
instrumentation that are involved. I'm going to discuss heat because
this is the subject I know most about. Someone else could very well
talk about instrumentation of human responses to toxic gases or the
instrumentation of human responses to noise. For every kind of
environmental stress that you might postulate, one could develop a
set of measurements of human responses that are fairly peculiar to
that particular stress.
I mentioned the basic importance of standardization. A second
important principle of even higher priority is answering the question,
Why make the measurement at all? It is very easy to run around
making measurements simply to be making measurements—without
a very clear idea of how they are to be used. I've done this myself.
Over a period of three summers I devised a good system of measuring
skin temperatures under working conditions. I took a lot of readings.
I still have them, but I don't really know what to do with them.
They don't really add to the story I was trying to investigate.
BODY TEMPERATURE
In discussing instrumentation for heat physiology, we start with
purpose. What is it one is measuring for? What is it about the
person's response that you need to investigate? This immediately
determines the scope of your attempts to measure. Body tempera-
ture has attracted man's attention ever since there were methods of
estimating temperature, certainly from Galileo's time on. Yet we
still have no really satisfactory method of measuring body tempera-
ture. Over the last 5 years I've been to three or four fairly high-level
conferences in physiology at which the measurement of body tem-
perature has been discussed, always with vigor and sometimes with
bitterness. Again, it is largely a question of definition: what do you
mean by "body temperature"? Do you mean the average temperature
of all the bodily tissues? Or do you mean the temperature of the
central core of tissue in the body, which may be quite different from
that of the periphery and therefore different from the mean tempera-
ture of all the bodily tissue? Or do you mean the temperature of the
blood going to the chief heat-regulating centers in the brain?
SKIN TEMPERATURE
Let us say that you want to measure skin temperature; how do
you do it? To measure skin temperature you can use thermocouples,
Lee 29
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thermistors, or a radiometer. The difficulty about a thermocouple
or a thermistor is to place it in close contact with the skin without
interfering with that skin. During the war it was fashionable to slap
thermocouples all over the skin and cover each thermocouple with
several layers of surgical adhesive tape. This procedure gave mar-
velously constant temperatures. But they weren't skin temperatures;
they were temperatures under several layers of surgical adhesive
tape. Nowadays we do it a little better. We can put the thermo-
couple on the skin without covering it with foreign material and so
obtain what we think is a good skin temperature.
MEASURING DEVICES
You may be interested in a device, recently invented, called the
Radio Pill. It is a very thick-walled capsule containing a transmitter
with a temperature-sensitive element. As the temperature of the
Radio Pill changes, the frequency of the emission from the trans-
mitter changes also. The subject swallows the pill, while you stand
with a little box and tune in to the frequency, reading from the fre-
quency setting the temperature of the pill at that time. You can
follow this pill all the way down, and if you are ingenious enough you
can even recover the pill and use it again. (I'm told that the average
number of uses is five.) This procedure gives you a core temperature.
If you want a mean temperature you must average out the core
temperature with the skin temperatures obtained according to an
accepted formula.
Another new gadget is a thermocouple put into the ear canal so
that it is almost in contact with the tympanic membrane. Some swear
that this device gives the body temperature; but as you see there are
a number of body temperatures, and one must decide which it is that
one wants.
SWEAT RATE
Suppose you want to measure sweat rate. Sweating is a means
of adjusting body temperature, and you can measure sweat rate in
various ways; the most common is by weighing. If you weigh the
subject clothed, before and after a period of exposure, you find the
amount of water evaporated from his skin. If you weigh him nude,
before and after, you get the amount of water lost from his skin.
Now these methods may give two different figures, but each is an
acceptable way of measuring sweat rate.
You may be interested, not in the total weight loss, but in the
sweat rate from a particular body area, or from different body areas.
For this measurement one generally uses a capsule. You can measure
the water loss from the capsule in various ways. You can pass dried
air through it and measure the water content of the air coming out,
or you can measure the difference in water content of the air going
in and that going out. Everybody has his own pet method- I object
to all except mine, of course. Again, you can see that with a dozen
30 HUMAN BIOMETEOROLOGY
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of these things on, a worker wouldn't be of much use to the pl-irt
manager.
OXYGEN CONSUMPTION
You may need to measure oxygen consumption. Why oxygen
consumption? Because by measuring the oxygen consumption one
can get a measure of the metabolic rate—the amount of energy being
generated by the individual and therefore the amount of heat being
produced by the individual. This is one side of the heat-balance
picture. To measure oxygen consumption, one hitches a man up to
a tank of air and measures the amount of oxygen used over a period
of time. From this one calculates the heat production. We are begin-
ning to believe that a lot of the long-term adjustment of individuals
to heat situations lies in learning how to do work with less heat
production.
CONSEQUENTIAL MEASUREMENTS
So far I have discussed the measurement of items in the heat-
regulating mechanism of the individual. But since in a complex body
you can't do any one thing without upsetting a lot of other things too,
other consequential disturbances are apt to develop in the course of
heat regulation. If you want to investigate these, then you need a
different set of techniques.
CARDIOVASCULAR SYSTEM
One of the systems that is very likely to become upset during
exposure to heat is the cardiovascular system. You just may not have
enough blood to fill up all those dilated blood vessels in the skin, to
keep up with the loss of water in the sweat, to keep up, perhaps, with
an undue consumption of food or alcohol, and at the same time to
keep up the supply of blood to the head. The simple things that you
can measure, like pulse rate, unfortunately, are open to all sorts of
influences other than the one you are investigating; such measure-
ments are to that extent suspect. One would like to measure blood
pressure, but the conventional way of measuring blood pressure is a
little crude. The most you can get are values at separate points of
time. You cannot follow rapid changes in blood pressure. About the
only way to follow rapid changes in blood pressure is with a catheter
in a blood vessel. You are very restricted in what you can do with a
catheterized man; you will be restricted as to the men that will let
you do it, too.
WATER SYSTEM
You may be interested in the amount of water in the body and
the distribution of water about different parts of the body. One
speaks of three compartments in the body—the blood stream, the
tissue fluid, and the cells. Water moves by a very complex set of laws
Lee 31
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from one compartment to another. As a result of changes in blood
vessels and the loss of sweat, it's quite possible for one compartment
to be without water or not to have enough. Measurements of the
distribution of water among these three compartments are not simple.
Fortunately, some substances will pass into one compartment but not
into another. If you inject a known quantity of one of these sub-
stances into the blood stream, its rate of disappearance from the
blood stream, as shown by successive samplings, gives a measure of
the volume of the compartment into which it is going. By using a
suitable battery of substances and by measuring at a suitable time
after the injections, you can get a fairly good indication of where the
water is in the body or where it isn't, which is usually the problem.
PULSE RATE
If, in spite of its drawbacks, you are interested in the pulse rate,
you can measure it by palpation at the wrist, which of course is the
common way. You can also measure it with a stethoscope placed over
the heart. But both are difficult when the man is marching, partly
because neither your finger nor the stethoscope will stay put, and partly
because the rate at which the pulse is beating is usually so close to
the rate at which the man is marching that you find yourself counting
the marching and not the pulse. One can also use the electrocardio-
gram. If you put one lead on the chest and another on the back, you
can get an electrocardiogram without too much interference from
the muscle action currents; then pick off the top of each R wave to
serve as a pulse counter.
Another method that is frequently advocated, especially by in-
strument manufacturers, involves an oximeter, which records varia-
tions in the blood flow through the ear lobe. It works very well for
determining the saturation or desaturation of the blood going through
the ear, but we have not found it very satisfactory as a pulse counter.
Others claim much more success.
RENAL FUNCTION
Renal function is something we would like to measure, but it is
very hard to get at. It can be estimated only indirectly by measuring
the volume of the urine, and the amount of a particular substance
like urea excreted in the urine, and then calculating the quantity of
blood that is cleared of a substance like urea in a period of time.
This is only a partial measure of renal function, however. Obtaining
a real measure of renal function is quite complicated and involves a
lot of induction from this kind of partial evidence.
NERVOUS FUNCTION
A consideration of nervous function is, of course, limitless. You
can divide and subdivide nervous function and devise all sorts of
measurement methods. Psychomotor tests are being used more and
more frequently for this purpose, particularly to determine speed of
32 HUMAN BIOMETEOROLOGY
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reaction, accuracy of reaction, and vigilance. During the war we
developed an experiment, in which we placed a trained gunner in a
mock tank, with the job of picking up a target and training his gunsight
accurately on it. We measured the time that elapsed between the ap-
pearance of the target on the screen and his actual accurate sighting
of the target. This was a measure of speed, accuracy, and vigilance.
We tried this under various conditions of heat and also of heat plus
noise. When we put the subject in very hot conditions his efficiency
dropped about 10 percent. When we applied noise through ear phones,
even up to 110 decibels, his efficiency did not drop any more. But
when we took the noise off, his efficiency increased by 15 percent. He
was better when we took the noise off than he had ever been before,
for a short while. After about an hour he slipped back to the 10
percent decrease again. So you see there is some point to the adage
about knocking your head against a wall because it is so pleasant
when you stop.
Cellular metabolism is now engaging our attention more and
more. We would like to know what goes on in the cells, particularly
what disturbances occur. If you are interested in this type of meas-
urement, you'll find increasing literature on it.
Earlier I mentioned an apparently insoluble problem: we would
like to have some measure of the total effect on the individual; not
what happens to his pulse, or his body temperature, or his sweat rate,
but what happens to him—the real him. Various formulas and charts
have been devised to approach this problem; they all give only partial
or very unsatisfactory answers. I will run through our attempts to
solve this problem, acknowledging in one gesture the 25 or 30 years
of work by dozens of people. A full account will appear in a forth-
coming volume of the Annals, New York Academy of Sciences, on
Biology of Human Variation.
QUANTITATIVE FORMULA
The quantitative expression of man's reaction to his thermal
environment poses a complex problem. Three sets of variables, each
containing several items or sub-sets, must be considered:
1. Environmental—temperature, humidity, air movement,
radiant heat, clothing insulation, and contiguity;
2. Individual—age, sex, body build, disease, hydration,
level of activity, acclimatization, and individual vari-
ability;
3. Evaluational (criteria for assessment of effect)—com-
fort-discomfort, sensation of distress, functional failure,
pathological developments, aggravation of previous de-
fects, susceptibility to other stresses, water requirements.
The problem of handling such a multiplicity of variables in
meaningful fashion can be logically dealt with in five steps:
Lee 33
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1 From heat-transfer equations devise expressions of interrela-
tionship between appropriate variables (activity level, temperature,
humidity, radiant heat, air movement, clothing insulation) and their
net significance for man.
Using Burton's (1, 2) equations and the concept of relative strain
introduced by Belding and Hatch(3), Henschel and 1(4) developed
the following approximate relationship:
M(Icw + Ia) +5.55 (ta —35) +RIa
7.5(44 — p.)
where RS is relative strain (dimensionless); M is metabolic rate
in kcal/sq m,hr; R is radiant heat gain in kcal/sq m,hr; ta is air
temperature in °C; Ia is insulation of air (inversely proportional
to square root of air movement) in clo units; Icw is insulation of
wet clothes in clo units; pa is vapor pressure of air in mmHg.
2. By postulating convenient "standard" values for metabolic
rate (M), air movement (IJ, clothing insulation (Icw), and radiant
heat (R), reduce expression to effect of two independent variables
(temperature and vapor pressure) on the dependent variable (rela-
tive strain); and draw lines of equal strain on a psychrometric chart.
3. From the expression for RS (relative strain), calculate the
changes in air temperature that would produce the same changes in
the value of RS as deviations from the "standard" values assigned to
the variables of metabolic rate, air movement, radiant heat, and
clothing insulation; and prepare tables to show "corrections" to
actual air temperature which, if made after entering the chart,
would compensate for such deviations.
4. From the data available in the literature and elsewhere,
determine the probable effect of successive degrees of relative strain
upon a defined "standard" person, in terms of selected evaluative
criteria, and express in graphical form.
5. Prepare similar graphic expressions of probable effects for
nonstandard persons.
The limited amount of useful data in the literature makes this
last step difficult. Evaluation charts will be found in the references.
The actual use of the scheme is comparatively simple:
a. From the appropriate table, determine any "correction" to
the actual air temperature needed to compensate for other than the
"standard" values assigned to metabolic rate, air movement, radiant
heat, or clothing.
b. With air temperature and whatever measure of humidity is
being used (wet bulb temperature, relative humidity, or vapor
pressure), enter the psychrometric chart. From the point so obtained
move horizontally to make the adjustment obtained in (a) and read
off the corresponding value of relative strain.
34
HUMAN BIOMETEOROLOGY
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c. From the chart of effects appropriate to the persons under
consideration read off the probable effects indicated for that value of
relative strain.
REFERENCES
1. Burton, A. C. An analysis of the physiological effects of clothing in hot
atmospheres. Rpt. of Aviation Med. Res. Assoc. Committee (Canada),
C2754, SPC 186. 1944.
2. Burton, A. C. and Edholm, O. G. Man in a Cold Environment. Wil-
liams and Wilkins, Baltimore. 1955.
3. Belding, H. S. and Hatch, T. F. Index for evaluating heat stress in
terms of resulting physiological strains. Heat., Piping, Air Condit.,
27(8), 129-136. 1956.
4. Lee, D. H. K. and Henschel, A. Effects of physiological and clinical
factors on response to heat. Ann. New York Acad. ScL, 134, 743-749.
1966.
DISCUSSION
Question: On your last slide you showed "discomfort", which
sounds something like the Weather Bureau's "discomfort index". Is
it true that you can get only so uncomfortable and then it is just
constant?
Dr. Lee: Yes. One of the troubles about using discomfort as a
criterion is that once you have reached a certain degree of dis-
comfort, any more does not count. From there on you're getting into
more serious changes. I might say that the word "comfort" presents
a philosophical difficulty. From my point of view, comfort is the
vanishing point 6f discomfort. There are no degrees of comfort.
Question: Dr. Sargent, you said that senescence is an accidental
byproduct of evolution. I'd like an explanation. By accidental you
don't mean "random"?
Dr. Sargent: No. If we look at the mechanism by which natural
selection operates, we find that this process is operative only during
the reproductive period. There is no natural selection for the aged.
The fact that we do age beyond the reproductive period can be argued
as an accidental byproduct of adaptive processes that have selective
advantages for the reproductive period.
Question: What do you think is the most effective measurement
of body temperature?
Dr. Lee: An argument is centered on whether one should meas-
ure the tympanic membrane's temperature, which is supposed to be
the closest you can come to measuring the brain; whether one should
measure the esophageal temperature as being closest to a core tem-
perature; or whether one should measure the rectal temperature,
which is much more easily obtained. It really depends entirely upon
what you are after. Recently in London I saw a chart with simul-
taneous plots of the temperature in the right heart, which is the tern-
Lee 35
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perature of the mixed blood coming back from all parts of thebodj
the temperature in the esophagus, the temperature in the tympanic
membrane, and the rectal temperature. No two curves agreed, they
were all different. You just have to decide which one suits your
purpose,
Question: You say they don't agree in value or shape?
Dr. Lee: Well, if a person were locked up in a room at the
same temperature all the time they would agree. But if there are any
changes in environment, these curves may not agree at all.
Question: I'd like to hear some comments on stress levels. Some
popular articles have been written on this. It seems to me there are
two sides. There is an advantage to an individual to be put under
stress, and then we've heard of disadvantages.
Dr. Lee: Complete isolation from external stress does not result
in an optimum condition of the body. The optimum condition of the
body apparently occurs with at least some external stress. After that,
one begins to pay for additional stress, first of all by the decline of
the advantages of mild stress and finally by negative values.
Question: Would you call that mild stress a stimulant, then?
Dr. Lee: Yes. If you take 20 people sitting down and measure
their pulse rates, you'll get a pretty wide range of pulse rates. If
you have them standing up, you'll get slightly higher pulse rates and
still a wide range. If you have them walking, say, at 2 miles an hour,
you'U get still higher pulse rates but the range will be narrower. At
some moderately high value, perhaps at 3%, you'll get a compara-
tively narrow range of pulse rates. If you start putting the stress
to them hard—getting them running up hill at something like 5 miles
per hour—then obviously the rates are going to spread out again, and
some people will drop by the wayside. So here one finds a range of
stress in which people become more uniform.
Dr. Sargent: Some people are improved, in a way, by these
stresses. Sir Joseph Barcroft discussed another aspect of this some
years ago in his book Architecture of Physiological Functions. Most
physiologists measure human beings under quite unusual conditions.
The standard conditions that we use are conditions of vegetation—
we are lying on a bed without having eaten anything for the past 18
hours, etc. These are not the conditions in which we are physiologi-
cally expected to get along, We should measure people under circum-
stances that are as consistent as possible with ordinary living con-
ditions. This bears on what Dr. Lee is saying. In a study at Harvard
University, the medical investigators used representative Harvard
students and put them through an experiment that involved sitting,
standing, standing on a treadmill, and running on a treadmill; re-
covery from this work was also followed. If one plots the coefficients
of variation, a measure of the interindividual difference of the sub-
jects, one finds that the interindividual variabilities were quite wide
when the students were sitting and standing. Then as they went
36
HUMAN BIOMETEOROLOGY
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through the treadmill run the variability became narrow. As they
recovered, the variance widened out again. This particular experi-
ment did not push the subjects, so some stress tends to reduce inter-
individual variance. What physiologists have to do is measure human
beings under realistic stresses rather than under extreme stress.
Question: Dr. Sargent, you mentioned the problems of a body
maintaining its chemical stability in winter. Have you any informa-
tion showing that there seems to be a time when certain diseases
tend to attack an individual because of this lack of chemical stability
or of a certain chemical which goes awry?
Dr. Sargent: The evidence that I showed from Dr. Momiyama
suggests that a great many diseases are beginning to concentrate in
the winter, that we're losing the summer maxima. The slide I showed
is from her data for Tokyo, but she found this true of all important
western countries where statistical data are reasonably good. The
generalization thus seems to apply to metabolic disturbance, infec-
tious diseases—to practically all diseases.
Dr. Lee: There's one exceptional case in regard to summer. The
highest mortality rates occur in a period of exceptionally hot weather.
The mean summer figures are much lower than the mean winter fig-
ures, but an exceptionally hot period gives the highest figures of all.
Dr. Surgent: The biochemical reaction that we showed was un-
covered in our studies on survival rations for the Air Force. The
increase of ketone bodies in the blood and the decrease of blood
sugar, the increase of nitrogen that developed in the winter is exactly
equivalent to an injection of insulin. We were even able to demon-
strate a negative phosphate balance in our subjects. I don't know
what this metabolic reaction means yet. The insulin reaction is really
an analogy. There must be some very important fundamental meta-
bolic change that occurred.
Question: Do you find that the first onset of winter—the first
cold spell—tends to cause cardiovascular problems or some other type
of illness to emerge?
Dr. Lee: Not necessarily. About 30 years ago Johns Hopkins
analyzed the relationship of respiratory morbidity to changes in tem-
perature. They found that a rapid change in either direction was
associated with increased morbidity. It didn't matter much whether
it was going up or going down. Of course, the changes in winter are
more rapid than in summer.
Question: Is this tendency toward increased mortality in winter
a world-wide trend or is it just in the United States?
Dr. Lee: It's world wide among the advanced civilizations, the
Western civilizations.
Question: Do you think that the increase in the use of air condi-
tioning could have anything to do with this? In ages past, or at least
Lee 37
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20 or 30 years ago, people were keeping relatively warm in the
winter, so there hasn't been any great change there; but in the
summer we have arrived at this mechanical means to cool our
environment.
Dr. Lee: There isn't much air conditioning in Britain.
Dr. Sargent: The trend applies to France, to England, to the
Scandinavian countries, and to the United States.
Question: Does it wash out as you go into more temperate
climates?
Dr. Sargent: Dr. Momiyama hasn't studied this particular aspect,.
as far as I know.
Question: What do you mean by more temperate?
Dr. Sargent: More moderate winters as you go south.
Question: Are her figures percentages?
Dr. Sargent: No, they're death rate—by months.
Dr. Horton: Some of your changes in the seasonal pattern of ill-
ness are due not to an increase in the winter but to a decrease in the
summer. The shape of the curve simply changes. The whole pattern
of intestinal illness in bottle-fed babies, which killed hundreds and
hundreds of infants every summer, particularly in August, in urban
United States back before about 1920 is essentially this. The disease
was found only in rural areas until 1946. When the Public Health
Service was about ready to study the problem, it disappeared. But
that is not a phenomenon of air conditioning. It's due to elimination
of flyborne intestinal illness largely in young babies.
Dr. Lee: We could put it this way: summer mortality is very
largely due to vector-borne diseases; whereas the winter mortality is
largely due to more contact with the disease.
Dr. Horton: It always has been. But at least the mortality of the
disease has been reduced, either naturally or through treatment. I'm
not sure that one could say that these diseases have been reduced.
Some of them have become less severe, such as scarlet fever, and
others have become more treatable, such as pneumonia.
Dr. Sargent: This same trend applies to cardiovascular disease
and cancer.
Dr. Horton: Part of this is due to the fact that some of these
diseases are due to terminal infection.
Question: Dr. Sargent, concerning the adaptability of the body,
has any attention been directed to this increase in stress by going
through the cycles of winter and summer year after year so that
the aged person reflects this more, say, than the younger' person?
Would this occur more in the temperate zone than with someone who
is always in the winter season, such as in the arctic, or someone who
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HUMAN BIOMETEOROLOGY
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is always in the summer season and doesn't have to endure the
cyclical changes?
Dr. Sargent: Very little has been done on this subject. You find
that some seasonal curves, such as for poliomyelitis and rheumatic
fever, are flatter in the tropics than in temperate regions. But we
have very little good information on the arctic regions.
Dr. Lee: There has been a lot of argument over the years about
the desirability of having change in climate. I think it is like a stress
situation. Complete lack of change is undesirable. A moderate change
is desirable. When the change becomes more than moderate, then you
start getting a stressful curve again.
Dr. Norton: I don't know that one can say that people living in
a place like Honolulu, for instance, which has about as little variation
as one can find, are any worse off than in other locations. Huntington,
for one, made a great point of the fact that the only people who
amounted to anything much were the people brought up in what
some people call the intemperate climate. This is a complex question.
Dr. Sargent: I think that the study of Kutschenreuter showing
the different effects of seasons on the various age groups should be
repeated. As far as I know, season and mortality were studied only
in New York City. I think this is probably a very important thing—
the fact that the seasonal variation of the mortality rate is different
for different age groups. [Recently Momiyama* has confirmed Kutsch-
enreuter's findings.]
Dr. Larsen: Some air pollutants seem to be about 5 times as
concentrated in the winter as in the summer. Have you any good
suggestions for filtering out the stress from air pollutants as opposed
to the stress from changes in meteorology?
Dr. Sargent: They go together. If it is nice and warm, there
won't be as much air pollution because you won't have to heat so
much. I think the effects of air pollution are quite frequently very
closely tied up with the effects of the weather. I don't have any sug-
gestions for filtering them out.
Question: Do you find that some of these seasonal adjustments
the body makes may throw off other functions of adaptation in the
body? Do you find that keeping a close regulatory effect on some of
the chemicals in the body can throw off other functions of the body
adaptation to the changes in the weather or climate?
Dr. Sargent: No. I don't think that is the right way to look at it.
The fact that we can keep certain aspects of our physiology so closely
guarded has great survival advantage for us because it keeps the very
essential functions of the cells, the systems, operating. We don't find
things getting out of gear in just the way you've asked.
* M. Momiyama and H. Kito. Papers in Meteorology and Geophysics, 14:
190-200(1963).
Lee
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Question: You mentioned low calcium in the winter time. Would
that be something related to, say, lack of sunshine or lack of vita-
min D?
Dr. Sargent: This gets us into this problem of seasonal variation
in the physical environment versus seasonal variation of the body.
The two are beautifully correlated. The literature gives some lovely
graphs, with correlation coefficients up to around 0.9 between calcium
and galvanic stimulation and incidence of tetany. They all go beauti-
fully together, and we know from independent physiological research
that there is an important interrelationship between the ultraviolet
component of the sun and the calcium and phosphorus metabolism.
Question: Could we say that if pollution causes decreased sun-
shine it causes vitamin D deficiency?
Dr. Sargent: Well, theoretically. But as Dr. Giel pointed out, we
get our vitamin D by other means now. By technological inventions
of man, in milk.
Question: Dr. Lee, is there any information on whether people
born and raised, let's say, in a southern climatic area are performing
a different physiological function from people in other areas? I was
with an occupational health group in Brazil, and my Brazilian col-
leagues never sweated the way I did. They never seemed to have
any visible sweat. Now these people—one was a boy of French extrac-
tion, one was a chubby Italian, some were of Negro extraction, and
others were Portuguese—but they always seemed to be cool and
comfortable.
Dr. Lee: Such investigation that has been carried out shows
virtually no effect of race; this has been a very disappointing field.
You'll find lots of statements in the older literature, but in most cases
they looked at only one side of the balance. For example, they would
see that this racial group sweated more than another racial group
without recording how much work they were doing, or the way in
which they went about doing the work. Remember I said that we
are beginning to realize now that a large part of the long-term ac-
climatization is learning to do the job with less expenditure of energy.
This is very important. The man who sweats less may do so because
he's just not doing the same amount of work or because he is working
more efficiently.
Question: One of the remarks that the physician made was that
Brazilians develop small pores. Is there such a thing?
Dr. Lee: No. I heard Dr. Weiner, who is probably the authority,
talk on this subject a couple of months ago, and he is very disap-
pointed. He can't find any racial differences. He has not looked at
very many racial groups, but so far he has not been able to find any
differences.
Dr. Sargent: I would like to comment on the question of heat
tolerance in the white versus the Negro, found in the literature in the
last few years.* In our survival studies a third of our subjects were
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HUMAN BIOMETEOROLOGY
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Negroes. The boys all went through identical procedures. To make
the analysis of our data more elegant, we matched them for body
size, height, weight, surface area, and lean body mass, within 10 % ;
we found 19 matched pairs. We compared about 20 different meas-
urements made on these men while they were resting and while they
were walking on a track for an hour in temperatures of 95 to 105°F,
dry bulb; there were no significant differences in the physiological
reactions. We also observed heat illness among these subjects. Only
one case of heat illness of any kind occurred among the Negro sub-
jects, and 21 cases of heat illness occurred among the whites. Our
physiological measurements showed nothing but that the Negro
showed more stamina. This is somewhat the conclusion that Wynd-
ham arrived at in comparing Bantus and Zulus with white people in
South Africa. The same conclusion was reached by Sid Robinson in a
study of share croppers years ago. I would agree with Dr. Weiner
on these differences of race: they are very difficult to establish. We
also have the very important question of how long these people have
been in a hot environment. We don't know how long it takes an
individual to acclimatize. We're doing a lot of research in chambers,
but you can't get anybody to live in a chamber for 10 years. You
can get them to live in a chamber for a couple of hours every other
day for a few weeks. We find that the rectal temperature and pulse
rate go down and the sweat rate goes up, so we say "Now he's ac-
climatized." But evidence now shows that with continued exposure
to heat the sweat rate actually starts to go down again. Such a finding
came from the Singapore lab of the Royal Navy, where they studied
people for 25 weeks. Maybe what we are studying in the chambers
is not "acclimatization'7 but "acclimatizing." The newcomer to the
hot areas shows high sweat rates and the natives in the tropics show
low sweat rates. We might look on this really as an overreaction with
a very long time phase. The homeostatic mechanisms have a large
variety of time sequences.
Question: When you spoke of these matched pairs and you said
there were no physiological differences in response, how did you
interpret this heat illness in the 18?
Dr. Sargent: By the vague term "stamina"
Question: It was a psychological response?
Dr. Sargent: No. We had total cessation of sweating, heat ex-
haustion, hyperventilation tetany, and things of this sort. There was
only one case of reduced sweating among the Negroes, but 21 cases
of heat illness occurred among the whites. This wasn't a feeling of
unhappiness or distress or discomfort.
Question: Weren't these measurable things then?
Dr. Sargent: Yes, they were measurable, but at the clinical level
rather than the physiological level. Maybe we weren't measuring the
* S. K. Riggs and F. Sargent, II. Human Biology, 36:339-352. 1964.
Lee 41
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right things physiologically to bring these differences out. Sund-
estrom realized this years ago. The ways people put together all their
adaptive reactions are quite different. Some people put them together
one way, and some another. Maybe you can't measure it all at once.
By using the standard procedures that most physiologists use today,
you couldn't see any difference. Other people have arrived at some
very interesting conclusions on the basis of similar measurements
where they found differences. Baker of Penn State has written some
delightful articles on "Climate, Culture, and Evolution," which you
all ought to read. He has studied Negroes at 85°F, which he called
moist heat stress, and then found some regressions between sweat
rate and temperature. He then extrapolated from his curves to ex-
plain racial differences in sweat rate all over the world. He found
only small differences.
Question: Do the results on the paired study on physiological
response suggest that it might be well to measure some of the more
sensitive variables, such as hyperventilation or sweat rate, or some
of these other things that seem more touchy or clinical?
Dr. Sargent: We measured sweat rate, pulse rate, rectal tem-
perature, skin temperature, and blood pressure at rest and standing.
We also measured oral temperature, blood pressure and pulse stand-
ing and sitting, and metabolic rate.
Dr. Lee: Hyperventilation is a bit hard to measure because
people are extremely sensitive to observation.
Dr. Sargent: We measured the maximum ventilatory capacity
as well as pulmonary ventilation and tidal air.
Question: What was the nature of the heat illness of the whites?
Dr. Sargent: One was anhidrosis, total cessation of sweating.
Another was a marked reduction of sweating, which we call hyper-
hidrosis. Neither of these was associated with a rise in body tem-
perature. And then there was hyperventilation tetany, which has
been ascribed to the heat, although it might be partly due to anxiety
because of the circumstances or to a panic reaction. We had one case
of heat exhaustion.
42 HUMAN BIOMETEOROLOGY
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CLIMATES OF THE UNITED STATES
Dr. Mark D. Shulman
Assistant Professor
Rutgers, The State University
New Jersey Agricultural Experiment Station
Department of Meteorology
Nichol Avenue
New Brunswick, New Jersey 08903
SUMMARY
As a result of the interacting effects of the wedge-shape of the
North American continent, the large land mass in northern latitudes,
the warm oceanic areas and currents in the south, the north-south
mountain ranges, and the large urban areas, distinct and different
air masses develop in appropriate source regions producing unique
types of climates in the United States. The temperature-humidity
index (THI), a climatic variable calculated from air temperature and
moisture and expressing the integrated effects of temperature and
humidity on human effort, is discussed.
INTRODUCTION
My topic is indeed a very, very broad area of study. Since I
teach a 3-credit course at Rutgers University entitled "Climates of
the United States," it was difficult for me to decide what specific
aspects of United States and North American climatology to deal
with. I finally decided to discuss the uniqueness of the climates of
North America and some of the main controlling factors that produce
the particular type of climate to which we are subjected. The second
part of my talk will deal with the distribution of two important
climatic parameters, temperature and precipitation, and the distri-
bution of a measure of human comfort, the temperature-humidity
index or THI.
CLIMATIC FACTORS
LATITUDE
Among the most important controlling factors of the climate
of any particular area, latitude must be included. The word "cli-
matology" or "climate" is from the Greek word "klimas," which
means angle of inclination. This refers to the angle of inclination of
the sun above the horizon, which is latitude-dependent and one of
the main factors of climate. Thus, the early Greeks knew that if one
Shulman 43
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proceeded north or south from a particular location a corresponding
change in climate would be observed. North America is a^very long
continent latitudinally, extending from about 10°N to /l> or ou J.N.
As you might expect, on the basis of latitude alone, there are broad
differences in climatic types.
TOPOGRAPHY
A second controlling factor of climate is the geographic setting
or the topography of the continent. Figure 1 indicates that the gen-
eral shape of the North American continent is that of a wedge, with
the broad anvil portion of the wedge in northern latitudes, narrow-
ing down considerably in southern latitudes. This shape has im-
portant ramifications in the type of climate we experience. Notice
also that most of the mountains in North America are oriented north
and south, in particular the Cordillera in the West and the Appala-
chians in the East. Considering the rest of the continental land
masses, one may recall that aside from South Am.erica, which is also
a wedge but inverted latitudinally, all other major mountain ranges
appear to be oriented east-west, in particular the Alps and the Hima-
layas. Thus, as a result of this factor alone, the climate of North
America is strikingly different from, that of Eurasia.
OCEAN CURRENTS
A third controlling factor is the ocean currents. Two current
systems, shown in Figure 2, affect the climate of North America. One
is the North Pacific drift, which comes across the central Pacific and
bifurcates when it strikes the North American Continent at about
40°N. This bifurcation results in a current moving from south to
north along the coast of Washington, Oregon, and British Columbia—
the Alaska current. The other current moves to the south—the Cal-
ifornia current. Since these two currents travel from middle lati-
tudes to either higher or lower latitudes, they tend to modify the
corresponding coastal climates. Thus, the Alaska current moving
from south to north is essentially a warm current; it warms the air
about it and tends to increase instability. The California current
moving to the south is relatively cold; since it is moving from higher
to lower latitudes, it tends to cool the air immediately above and has
a general stabilizing effect. These air-sea interactions are of notice-
able importance in the general climate of the area.
In the Atlantic, we have the Gulf Stream system, emanating from
the Florida straits and paralleling the North American coast in a
northeasterly direction just off the continental shelf. This system
becomes the North Atlantic drift and moves across the North Atlantic
ocean. Since the general movement of winds in mid-latitudes over
North America is from west to east, the currents in the Pacific have
a more profound effect upon the general climate than does the Gulf
Stream in the Atlantic.
HUMAN BIOMETEOROLOGY
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Figure 1 — Orientafion of major mountain ranges of North America.
PRESSURE SYSTEMS
The next factor controlling climate is the existence of the atmos-
pheric semipermanent pressure systems. The Bermuda High, the
semi-permanent high-pressure system off Southern California, the
Aleutian Low, and the Icelandic Low are examples of such systems.
These semipermanent pressure systems, which are statistical in
nature, perform the very important function of distributing moisture,
momentum, and heat energy in the atmosphere. If these giant rotors
did not exist, the earth, which receives most of its energy from the
sun in low latitudes, would tend to become overheated in low lati-
tudes and supercooled in higher latitudes.
URBAN AREAS
The fifth controlling factor is urban areas. You may think it
strange to consider this factor, but urban areas do produce a pro-
Shulman
45
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nounced effect on their climate. Such an area tends to influence its
local climate as a result of changes in albedo, evaporative surfaces,
heat capacity, and so on. Since this subject is more properly a func-
tion of microclimatology, let it suffice to mention that cities in contrast
to non-urban areas tend to have generally higher temperatures,
greater amounts of rainfall, greater amounts of fog, and lower relative
humidity.
Figure 2 —• Major ocean current systems affecting North America.
AIR MASSES
Before we discuss the distribution of precipitation, temperature,
and the temperature-humidity index over the United States, let us
briefly consider a combination of these factors to describe the unique-
ness of the climate of North America. As a result of the wedge-like
shape of the continent, with a large land mass in northern latitudes
and warm oceanic areas to the South, combined with north-south
mountain ranges, we have perfect conditions for the development of
distinct and different ah\masses in appropriate source regions. Fig-
ures 3 and 4 show the source regions and trajectories for some of the
major air masses that affect the North American continent during the
two extreme seasons, winter and summer. The arrows indicate the
general trajectory of these different air masses. Several major air
masses affect, at least, the greater portion of the country east of the
Rocky Mountains. Two are the cP (continental polar) and cA (con-
46
HUMAN BIOMETEOROLOGY
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tinental arctic) air masses originating in the north; these are usually
cold, dry, and unstable. These air masses move in roughly north to
south trajectories. Another important air mass is the Gulf mT
(maritime tropical) air mass, which generally moves from the Gulf
of Mexico, its source region, to the north. Other air masses that
affect mainly the coastal regions of the Atlantic and the Pacific are
the mT in the Pacific and the mP (maritime polar) in the North
Atlantic and North Pacific.
Figure 3 — North American air mass source regions and trajectories (winter).
Figure 4 — North American air mass source regions and trajectories (summer).
Shulman
47
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LOW PRESSURE SYSTEMS
Air masses are distinguishable according to peculiar and distinct
characteristics and are separated from each other by frontal surtaces.
According to the Norwegian theories of cyclogenesis, fronts are usu-
ally associated with traveling low-pressure systems or cyclones,
which are the main producers of inclement weather. The movement
of these low-pressure systems, with their attendant fronts, cold and
warm, provides the mechanism for the movement and distribution of
these various air masses over the United States. Figure 5 indicates
the general paths or trajectories of these traveling cyclones or low-
pressure systems, as well as those of some of the major anticyclonic
or high-pressure systems. 'Note that the general path of these pressure
systems is in a west-to-east direction, which is in line with the gen-
eral movement of winds in midlatitudes. Note also the general
convergence of storm tracks over the northeastern United States.
Some of these paths include that of the Alberta low, Colorado and
Texas low-pressure systems, Gulf lows and east-coastal low-pressure
systems. It appears that lows are most intense and are associated
with the greatest amounts of precipitation when they are moving in
a south to north direction. This is in line with the fact that the main
sources of moisture for these storms are the Gulf of Mexico and the
Atlantic Ocean.
As a result of these factors North America, the United States in
particular, is blessed with an abundance of unusual climatic phe-
nomena; unusual because of their great frequency of occurrence and
intensity. Such climatic "delights" include tornadoes, blizzards, dust
storms, thunderstorms (with and without hail), and abundant rain.
TEMPERATURE
One way of getting a good feeling for the climate of an area is
to take a detailed look at the distribution of certain climatic elements.
As I indicated earlier, we will consider temperature, precipitation,
and the temperature-humidity index. Let's start with the distribu-
tion of temperature and consider the two extreme seasons, in par-
ticular the months of January and July.
DISTRIBUTION IN JANUARY
Figure 6 shows the patterns of isotherms, lines connecting equal
temperatures, over the United States during January. Notice the
effects of the oceans. The isotherms appear to reach their southern-
most extent in the interior of the country and are bowed upward to
the north along the Atlantic and the Pacific coasts. This effect is most
pronounced along the Pacific, where isotherms parallel the coast for
considerable distances. The change in temperature with latitude
varies considerably from one part of the country to another. The
temperature gradient from Maine to Florida corresponds to about
2.5°F per degree latitude. This means that someone in the northern
part of the United States traveling south along the eastern seaboard
48 HUMAN BIOMETEOROLOGY
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for his winter vacation at approximately 70 miles per hour on the
new interstate highway systems, could expect to gain 2.5°F for each
hour of travel. This, of course, refers to mean or average conditions.
In the interior of the country from Minnesota, say Duluth, to New
Orleans, the change in temperature or temperature gradient is ap-
proximately the same. Along the west coast of the United States,
because of the moderating- effect of the ocean and general onshore
breezes, the temperature gradient is only about 0.8 °F per latitude
degree.
Figure 5 — Main cyclone tracks (solid lines) and anticyclone tracks (broken lines) over
North America.
Look at two particular isotherms, the 0° isotherm and the 30°
isotherm. The 0° isotherm enters the country in the northcentral
plains in the vicinity of eastern North Dakota and northwestern
Minnesota, quickly returning to Canada/ The 30° isotherm, however,
has a considerable traverse across the United States. It enters the
eastern seaboard in the vicinity of New York City, progresses to the
south and west, bows toward the equator in the Appalachian moun-
Shulman
49
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tains, then proceeds through the Ohio valley in the vicinity of Cin-
cinnati, through the Mississippi valley a little north oi St. Louis, and
into the plains in the vicinity of Denver. At this point it becomes
extremely erratic because of the effects of the mountains, It re-
appears in northcentral California and generally parallels the coast
(notice the effect of the Columbia River valley), never actually
touching the ocean until southern Alaska. Once again, this contour
is due to the modifying effects of the Pacific Ocean.
ROCKY MOUNTAINS
Also noteworthy in Figure 6 is the barrier that the north-south
Rocky Mountains present to the marine air from the Pacific moving
in from the west, and its subsequent effect on the isotherms. Note
also that in the immediate lee of the Rocky Mountains temperatures
are somewhat warmer than in the Plains farther to the east. This is
due to what is known as a Chinook effect, in which air conies over
the tops of the Rocky Mountains, descends the lee side, and warms
adiabatically—that is, in a thermodynamic sense without the addition
of heat. These Chinook winds are thus warm and dry, and result in
the evident modified isothermal pattern.
GREAT LAKES
Another interesting point in Figure 6 is the effect of the Great
Lakes. The Great Lakes generally do not freeze during the winter.
The only one that does freeze with any consistency is Lake Erie,
which freezes because of its shallower depth. As a result of open
water, air passing over the Lakes in a general west-to-east direction
becomes modified with increased moisture and warmer temperatures.
This net effect is seen when we compare the temperatures of several
cities in central Wisconsin on the windward side of the Lakes and
other cities in central lower Michigan on the lee side of Lake Michigan
but at approximately the same latitude. For example, the mean
January temperatures for such cities as Madison, LaCrosse, and sev-
eral other smaller stations in Wisconsin, such as Richland Center,
are between 15 and 18°F. Cities in Michigan, such as Muskegon,
Flint, and Grand Rapids, which are affected to a much greater extent
by the proximity of the Great Lakes, record mean January tempera-
tures that range from 23 to 26°, considerably warmer. Occasionally,
local and smaller topographic effects are evident on the mean iso-
thermal pattern. One case in point might be the Hudson Valley and
Lake Champlain. This area appears somewhat warmer than the sur-
rounding countryside, mainly because of differences in elevation.
ABSOLUTE MINIMUM
Figure 7 indicates the extreme isotherms for the winter season.
These values are the coldest temperatures ever recorded regardless
of time of observation. Absolute minimum temperatures occur in the
mountain states of Montana and Wyoming, where values of —60°F
have been recorded. The — 40°F isotherm is found in the Great
50 HUMAN BIOMETEOROLOGY
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Plains, in isolated portions of New England, and in northern Wis-
consin and Minnesota. At —40 °F and below, mercury freezes and
observers must use spirit thermometers to record these temperatures.
Notice further the effects of the Great Lakes on the extreme iso-
therms. Absolute minimums along the shore are considerably higher
than those recorded some distance inland; this temperature difference
has an important effect on the economy of the region, with fruit
belts along Lake Michigan and Ontario. Fruit trees that normally
Figure 6 — Average January temperature in the United States (°F).
Figure 7 — Lowest temperatures ever observed in the United States (°F).
Shulman
51
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could not exist in such areas because of poor tolerance for low tem-
peratures flourish in the vicinity of the Lakes.
DISTRIBUTION IN JULY
Let us now turn to the mean or average temperature distribution
over the United States for the month of July, generally the hottest
month, as shown in Figure 8. Note first the more uniform distribu-
tion of the isothermal pattern. Take a look at the 70° and 80° iso-
therms and track them as they traverse the country. A goodly por-
tion of the United States falls between these two lines. Also the
north-south temperature gradients are considerably less than during
the winter. The change of temperature with latitude is now greatest
in the central part of the country, where the temperature gradient
from Duluth, Minnesota, to New Orleans, Louisiana, is approximately
1°F per degree latitude. Along the East Coast from Eastport, Maine,
to Key West, Florida, the gradient is approximately 0.8°F per degree
latitude. On the West Coast the temperature gradient is still smaller;
from northern Washington to San Diego it is approximately 0.7°F
per degree latitude. As indicated in Figure 8, most of this gradient
occurs south of San Francisco.
As before, the effect of topography is evident in that somewhat
cooler temperatures are experienced in the mountains of the East
and particularly in the Rocky Mountains. The hottest portion of the
United States occurs in the desert Southwest, where mean tempera-
tures approaching 100°F are found in some isolated spots. Another
interesting point is the extreme temperature gradient of the south-
west coast. The immediate shoreline is quite cool in association with
the cool ocean currents and the general west-to-east flow of air. The
interior is exceedingly warm for several reasons. The rain shadow
effect of the mountains causes the interior areas to be dry and support
little vegetational growth. Hence little plant moisture is available
for evaporative cooling. Also, because of the decreased amount of
cloudiness, the sun's rays are allowed to strike unimpeded on the
surface, producing the very warm temperatures. This sharp east-west
temperature gradient results in the very great frequency of sea
breezes.
Figure 9 indicates the pattern of the extreme isotherms of maxi-
mum temperatures for the summer. As with the mean isotherms,
one is struck by the relative uniformity of the pattern. Most of the
United States has had temperatures above 100°F. This is true except
for a few isolated and exceedingly maritime areas, such as the coastal
northeast in Maine, in the immediate vicinity of the northwestern
Great Lakes, and the coast of extreme northwestern United States.
As before, the effects of topography are evident in the deflection of
isotherms due to the mountain areas and the modifying effects of the
Great Lakes. Highest temperatures ever reached in the United States
occur in the desert Southwest, where absolute maximum tempera-
tures of greater than I25°F have been attained. In Greenland Ranch,
California, a temperature of 134°F has been recorded
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Figure 8 — Average July temperature in the United States (°F).
Figure 9 — Highest temperatures ever observed in the United States (°F).
PRECIPITATION
The second climatic parameter we will discuss is precipitation.
Figure 10 shows the distribution of annual precipitation over the
United States. This distribution is shown by the pattern of isohyets
or lines of equal annual precipitation. The most remarkable thing
about the precipitation of the United States, the eastern third of the
nation in particular, is the abundance of well-distributed precipita-
tion. The 40-inch isohyet which encompasses a land area with very
Shulman
53
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adequate precipitation covers the southeastern third of the country.
The 20-inch isohyet, generally taken as the dividing line between
semi-arid and sub-humid types of climate, proceeds from central
Texas, in a north-south direction, approximately along the 100th
meridian before it enters into Canada.
Figure 10 — Average annual precipitation in the United States (inches).
SOURCE
As indicated earlier, the main source of moisture for the greater
portion of the United States is the Gulf of Mexico; the Atlantic Ocean
is a secondary source. Evidence of these moisture source regions is
seen in the general pattern of the isohyets which are oriented north-
south in the central part of the country and east-west across the
northeastern tier of states. Thus, the general moisture gradient is
from southeast to northwest. This is further illustrated by the mois-
ture differentials between selected points. For example between
St. Paul, Minnesota, and New Orleans, Louisiana, the precipita-
tion differential amounts to 30 inches, indicating a pronounced
decrease in precipitation from south to north. From St Paul Minne-
sota, to Eastport, Maine, the precipitation differential amounts to 15
inches; thus although precipitation increases from west to east this
increase is not as great as that from south to north.
GREAT LAKES
«. ,AS T haVe n°ted' the Great Lakes have an important effect on
the distribution of temperature in the immediate area- their effect on
precipitation, however, is a minor one. Although, during certain por-
tions of the year, particularly in the fall when cold air from the
54
HUMAN BIOMETEOROLOGY
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Northwest traverses the warm waters of the Great Lakes and pro-
duces instability snow showers, the Great Lakes generally act as a
very weak source of moisture. In fact, the stabilizing effect of the
Great Lakes during the summer season, and the resultant inhibition
of thunderstorms, usually reverses any tendency toward higher
annual precipitation.
ROCKIES
Very evident in Figure 10 is the rain shadow effect of the Rockies.
Air moving in from the West is forced to rise over the Rockies, and
loses much of its moisture in the ascent; it descends exceedingly dry.
Hence a great portion of the land immediately to the lee of the
Rockies can support no major vegetation other than grass. Other
orographic precipitation effects are seen in the various highlands of
the East. For example, in northern Georgia, in the Catskill and
Adirondack Mountains of New York, and the White Mountains of
New Hampshire. The driest portion of the United States is the desert
Southwest—in Nevada, southeastern California, and southwestern
Arizona. The extreme aridity is due to the rain shadow effects of
the Rockies acting in combination with other dynamic factors.
WEST COAST
The precipitation profile of the West Coast of the United States
is interesting in that the precipitation gradient is reversed in com-
parison to those of the interior of the country and the East Coast.
That is, precipitation is least in the southern portions and increases
to the north. Two controlling factors determine this precipitation
regime. One is the existence of a subtropical high-pressure system,
with its associated subsiding and stabilizing air flow, situated off the
southern California coast. This system affects the southern part of
the coast to an extent, the effect diminishing to the north. The second
factor is the ocean currents. The California current moves from
north to south, allowing cooler water to be brought in, which further
inhibits precipitation over the area. Furthermore, because of the
rotation of the earth, the north-to-south-flowing current is affected
by the coriolis force, which causes a net offshore transport of water.
This allows cold bottom water to upwell along the immediate coast-
line, lowering the temperature of the surface water and adding to
the general stability of the air immediately above.
PRECIPITATION REGIONS
Figure 11 indicates more adequately the seasonal distribution of
precipitation on a month-to-month basis over the United States.
Certain portions of the United States can be characterized by the
similarity of precipitation profiles. Thus, the United States could be
divided into some seven different areas that have similar precipitation
regimes.
Shulman 55
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lll'nll
Jill
*,.;,»
Figure 11 — Normal total precipitation by months for selected stations in the United States,
CENTRAL UNITED STATES
The first area, denoted as the central United States regime, in-
cludes Iowa, Minnesota, Missouri, and Wisconsin. This region is
characterized by a single pronounced maximum of precipitation in
the growing season (note the tendency in certain portions for a weak
double summer maximum). In fact, 80 percent of the precipitation
occurs during the time of vegetative growth, when precipitation is
needed most. The summer maximum of precipitation is due to the
depth of penetration of Gulf air with its associated moisture and
thunderstorm activity. During the winter the prevalent cP air is
dry, associated with surface anticyclones, and tends to inhibit pre-
cipitation.
OHIO VALLEY
The second precipitation regime is that of the Ohio Valley and
vicinity. In this area a single precipitation maximum is still evident.
In most cases it is equal to that of the central United States, the main
difference being that there is more abundant precipitation in the
winter season. Thus, while the general outline of the curve is similar
to that for the central United States, the 'tails' of the curve are
higher due to the resultant greater total precipitation.
NORTHEAST
The third distinct precipitation regime is found in the Northeast,
including New England and New York State. Note the uniformity of
the month-to-month precipitation. This abundant, well-distributed
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GPO 8O1—494—a
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precipitation is due, as we have seen, to the convergence of the storm
tracks over this portion of the country. This area may be further
divided into the subregions. In one, along coastal New England, there
is a slight tendency for maximum precipitation in the winter, as in
Boston, Massachusetts, and Portland, Maine; in the interior and
southernmost sections, although uniformity is maintained, there is a
tendency for a summer precipitation maximum.
SOUTHEASTERN
Another general precipitation regime is the sub-tropical type
located in the southeastern United States. This area is characterized
by large total amounts of precipitation, in some places from 50 to 60
inches, with a pronounced summer maximum due to thunderstorms.
Florida has an unusually high incidence of thunderstorms during the
summer because of a double Seabreeze effect. Since Florida is a
peninsula, sea breezes are possible on both its Atlantic and Gulf
coasts. When this double sea breeze effect is in operation, the air along
the surface converges in the central portion of the peninsula. When
this convergence occurs, there is no pluace for the air to go but up. As
the air lifts, the vast amount of moisture available and the general high
temperatures allow the formation of frequent heavy thunderstorms,
resulting in the abundant summer precipitation.
TENNESSEE
Another rather distinct precipitation regime is the Tennessee
precipitation type, which shows a pronounced winter precipitation
maximum but also abundant precipitation during the summer. The
high winter precipitation is probably due to local topographic effects
and the relative closeness to the main storm tracks. Also the greater
distance from the Gulf decreases the summer thunderstorms.
PACIFIC COASTAL
Turning to the far West, we have the Pacific coastal precipitation
regime which is characterized by a strong winter maximum of pre-
cipitation and, perhaps more noteworthy, by the migratory nature of
the time of maximum. In northern -British Columbia and coastal
Alaska, the wettest month of the year occurs in late October and
November. As one proceeds south along the coast, there is a pro-
gression in the time of the precipitation maximum. In the southern
British Columbia and Washington area the precipitation maximum is
in December. Southward, in Oregon and northern California, the
time of maximum precipitation is in January. In San Francisco, Los
Angeles, and San Diego the maximum is further delayed, occurring
from January through the end of February. The controlling factor is
the migratory nature of the subtropical high-pressure system located
off the coastal part of southwestern United States. In response to
the seasons this high-pressure system migrates north and south, with
its resultant effect on the precipitation pattern of the area.
Shulman 57
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ROCKY MT. AREA
The last general precipitation regime is in the Rocky Mountain
area. This region is a transitional zone between the areas of pro-
nounced summer maximum precipitation in the plains and the central
United States and the noteworthy winter maximum along the West
Coast. There is a general uniformity although not a great abundance
of precipitation. In the southern part of the mountain regime, in
Arizona, for example, there is a double precipitation maximum; a
weak summer maximum associated with thunderstorms and air mov-
ing in from the Gulf of Mexico and a winter maximum associated
with Pacific air and the movement of cyclonic storms across the
region.
TEMPERATURE-HUMIDITY INDEX
Temperature and precipitation are directly measureable cli-
matic elements and are important determinants of human activities.
The temperature-humidity index or THI is a compound climatic vari-
able, calculated from air temperature and moisture, and is directly
associated with human comfort.
Values of the THI may be calculated with any one of the follow-
ing linear equations; the choice of equation depends on the ease of
its application to available data. The equations are,
1) THI = 0.4 (TD + Tw) +15
2) THI = 0.55 TD + 0.2 TDP -f 17.5
3) THI = TD — (0.55 — 0.55RH) x (TD —58)
where the dew point temperature (TDP) is in degrees fahrenheit, as
are the dry bulb (TD) and wet bulb (Tw) temperatures. RH is the
relative humidity in percent. Nomograms have been devised to sim-
plify the calculation of THI data.
According to the developers of this index, when the THI reaches
70, 10% of the population will be uncomfortable; when the index
passes 75, more than half will be uncomfortable; when it reaches 80,
just about everyone will be uncomfortable. Figure 12 shows the
distribution of the THI over the United States for the month of July
and indicates areas of relative maximum, moderate, and minimum
discomfort. The THI values are calculated from monthly mean values
of temperature and humidity recorded at 12 noon, local time.
Regions of maximum discomfort occur in the south-central and
south-eastern part of the United States; in the area to the south of
the 80 isoline a combination of high temperature and humidity are
the cause. Another area of maximum discomfort exists in the desert
southwest, centered in southern Arizona. Here it is not the humidity,
as the popular expression would have it, but the heat, at the time of
observation, that causes the discomfort.
Much of the country lies between the 70 and 80 isolines, indi-
cating moderate discomfort, with increasingly better conditions to
58 HUMAN BIOMETEOROLOGY
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Figure 12 — Distribution of THI in the United States during July.
the north. Areas of "comfort" include the extreme northern portion
of the United States, including a goodly portion of the higher eleva-
tions of the northern Rockies, much of the State of Washington, and
the western half of Oregon. Not to be neglected, in all fairness, is
the extreme coastal region of southwestern California. The 'comfort'
of this last area may be due to the relative coolness of the offshore
waters in association with the dynamic factors discussed earlier.
CONCLUSION
In concluding this discussion, I would like to reiterate my objec-
tives. One was to discuss the main controlling factors of climate
influencing North America, the United States in particular. These
factors working together produce certain distinct climatic "types"
that have no specific counterparts anywhere else in the world. The
distribution of temperature and precipitation, often considered as the
most important of the many climatic parameters, were evaluated in
detail. The THI, a compound climatic element expressing the inte-
grated effects of temperature and humidity of human comfort, was
discussed. Its distribution over the United States for the month of
July was presented and briefly analyzed. It is hoped that this presen-
tation of the distribution and general pattern of these elements helps
give a general picture of the climate of the United States.
SUGGESTED READING
Bryson, R. A., and Lowry, W. P. Synoptic Climatology of the Arizona
Summer Precipitation Singularity. Bulletin of the American Meteoro-
logical Society. Vol. 36, No. 7, Sept. 1955.
Shulman
59
-------
Climate and Man, Yearbook of Agriculture, United States Department of
Agriculture. 1941.
Horn, L. H., and Bryson, R. A. Harmonic Analysis of the Annual March of
Precipitation over the United States, Annals of the Association of
American Geographers, Vol. 50, No. 2. June 1960.
Landsberg, H. Physical Climatology, Gray Printing Co., Dubois, Penn.
1962.
Thorn, E. C. The Discomfort Index, Weatherwise, Vol. 12, No. 2, April.
1959.
Trewartha, G. T. The Earth's Problem Climates, The University of Wis-
consin Press, Madison. 1961.
United States Weather Bureau Publication, (map back), Temperature
Humidity Index. Revised Aug. 1960.
60
HUMAN BIOMETEOROLOGY
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MICROCLIMATOLOGY
Professor A. Vaughn Havens
Chairman, Department of Meteorology
Rutgers, The State University
New Brunswick, New Jersey 08903
SUMMARY
This discussion of microclimatology is concerned with the bound-
ary layer of air where the earth's surface energy exchange is effective.
In this area, which may vary in height from a jew hundred feet to
several thousand feet, the relationships of pressure gradient, coriolis
effect of the earth's rotation, and wind speed and direction as expressed
in classical principles do not apply. The microclimate is modified by
various activities of man (e.g., crop-protection techniques of heating
and windbreaks, construction of structures, and the build-up of
urban areas) and by topography, including all variations in altitude
and slope, however slight. Figures are given that illustrate the inver-
sion temperature phenomenon, important in any study of air pollution.
INTRODUCTION
We have heard a great deal in recent years about efforts to
modify the weather and climate. This subject has been abused in the
press and in other writings perhaps more than any other topic in the
field of meteorology. To be sure, some very interesting and very good
legitimate research is being done in cloud physics and in other topics
related to man's efforts to modify weather and climate. But we are
certainly a long way from being able to influence or control the
weather on a large scale. What is often overlooked is that we can
and we do, practically every day of our lives, modify the micro-
climate, the small-scale atmospheric environment in which we live
and work. I shall mention just three examples.
EXAMPLES OF MODIFICATION
Probably of greatest importance to agriculture are the efforts to
prevent frost damage to crops, an ideal example of modification of
the microclimate. The entire purpose of all types of frost-protective
equipment or techniques,—whether they are orchard heaters, or wind
machines or the flooding of a cranberry bog—is to modify the imme-
diate atmospheric environment of the crop so as to prevent serious
frost injury.
Farmers modify the microclimate in another way by erecting
windbreaks. In contrast to the various methods of protecting a crop
from frost, a windbreak has just the opposite effect. To prevent frost
we often try to create wind—we stir up the lower layers of the atmos-
phere. When we erect a windbreak we do just the opposite—we
reduce air movement. This creates a somewhat more excessive micro-
Havens 61
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climate, but it also alleviates some of the unfavorable aspects of
strong winds, particularly when accompanied by low humidity.
Whenever we erect a building of any kind, we modify the micro-
climate in the immediate vicinity. All of you are very familiar with
the effects of a building on the immediate microclimatic environment.
I have lilacs planted on both the north and the south sides of my
house; this difference of exposure causes a difference of as much as
2 weeks in the date of blossoming of these lilacs.
One of the best experts on the effects of building and landscaping
on the microclimate that I have observed was a pet cat. In the winter
this cat invariably sought out a place that was protected from the
wind and fully exposed to the sun; she seemed perfectly comfortable
in temperatures well below freezing. In the summer the cat found
the breeziest spots around the house, or stayed underneath the shrub-
bery, where the soil was moist and temperatures much cooler than in
the open. Wild life of all sorts instinctively construct nests or shelters
to alter the immediate microclimatic environment in a manner that
is beneficial.
APPROACHES TO MICROCLIMATOLOGY
We can distinguish two different but closely related approaches
to microclimatology. At Rutgers University, because of our affiliation
with agricultural research, we are interested in what might be called
the vertical viewpoint of microclimatology, closely aligned with the
approach discussed by Dr. Geiger in his book "The Climate Near the
Ground." Certainly the climate very near to the soil surface or near
to the vegetative surface is quite different from that which we meas-
ure in a standard instrument shelter at a height of 5 or 6 feet above
the ground.
If we are concerned with human microclimatology, the standard
instrument shelter is quite useful for indicating the climate as it
affects humans. This has been referred to as the horizontal view of
microclimatology because in using these measurements made at a
height of 5 or 6 feet above the ground, we record sizable differences
in climate at nearby locations. Many other aspects of local exposure
conditions influence the microclimate. Topography is the most obvious
one. As Dr. Dill has indicated, there are tremendous atmospheric
variations with altitude. But on a much smaller scale than the great
heights that Dr. Dill discussed, the slope of the ground, the exposure
with regard to surrounding buildings and trees—all exert a definite
influence on the microclimate.
BOUNDARY LAYER
In this discussion of microclimatology we are dealing exclusively
with the boundary layer of the atmosphere. I shall not attempt to
put strict limitations on this boundary layer. Under certain circum-
62 HUMAN BIOMETEOROLOGY
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stances it may extend upward several thousand feet. Under other
circumstances the boundary layer, the layer in which the friction of
the earth's surface influences the atmosphere significantly, may be
limited to a few hundred feet. Whenever we talk about microclimatol-
ogy, we are talking about this boundary layer in which the flow of
the atmosphere is turbulent and in which nonadiabatic heating and
cooling processes take place. These are points at which microclima-
tology departs from classical meteorology.
In classical meteorology, particularly when we deal with the free
atmosphere above the boundary layer, we think of air flow as being
almost entirely horizontal, and to a large extent this is true. We can
mathematically describe the relationship between pressure gradient,
the Coriolis effect of the earth's rotation, and wind speed and direc-
tion. The weather analyst and weather forecaster use these principles
continually. In the boundary layer when we deal with turbulent
flow near the earth's surface, these relationships become much more
complex. Anyone who attempts to predict surface wind mathemat-
ically on the basis of the various forces involved is bound for frus-
tration. Also in analyzing the stability of the atmosphere, the mete-
orologist deals with processes that are assumed to be essentially adia-
batic, meaning that no heat is gained or lost from the surroundings.
To a great extent the free atmosphere does fit this description. It
is nearly adiabatic, and so we can use adiabatic principles in analyz-
ing the stability of the atmosphere above the boundary layer. In
dealing "with the boundary layer, particularly the layer immediately
adjacent to the ground in which heat is exchanged between the earth's
surface and the atmosphere, nonadiabatic processes make all the
difference. Our classical meteorological principles simply do not
apply to this layer of the atmosphere.
Microclimates deviate most strongly from our standard climates
during periods of fair weather with very little wind. Strong winds,
which bring about a great deal of vertical mixing in the lower layers
of the atmosphere, are quite effective in destroying microclimates.
Weather reports during a period of stormy weather with extensive
cloudiness and strong winds, indicate that temperatures over a large
area are uniform. Changes from daytime to nighttime are very slight.
The boundary layer of the atmosphere under these circumstances is
greatly disturbed, mixing is good, and conditions are uniform.
For all practical purposes microclimate is virtually eliminated
under these conditions. In periods of clear skies with rela-
tively light winds, microclimate is greatly exaggerated. At Rutgers
University we are only 30 miles from New York City, and so we are
keenly aware of the tremendous differences that can exist between
the city and the suburbs. Minimum temperatures at the Agricultural
Experiment Station in New Brunswick are often 20 degrees lower
than those recorded in Central Park in New York City. And Central
Park is much more exposed than some of the heavily built up areas
in the city. In contrast, during periods of strong winds and cloudy
skies the temperatures in New Brunswick and New York City may
differ only 1 or 2 degrees.
Havens 63
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SOLAR RADIATION
Dr. Geiger introduced the concept of active surface. Though
somewhat of an oversimplification, it is a useful concept. Geiger de-
scribed the active surface as the primary receiver of solar radiation
and the primary emitter of terrestrial infrared radiation. Geiger
conceives of this as the surface at which our radiative exchange takes
place. I call it an oversimplification because we know that in forests
or in other types of complex natural vegetation or crops one surface
is not the primary receiver of solar radiation or emitter of terrestrial
radiation. Many different surfaces are involved and the whole subject
of radiative exchange at the earth's surface is very greatly influenced
by the complex surfaces that exist.
In regard to human bioclimatology man has been modifying the
active surfaces that influence our microclimate for a long time, and
I'm afraid is doing so at an increasingly accelerated rate. An extreme
example of this occurs when a park or woods or other natural surface
is replaced by a flat black-top parking lot; the temperatures and the
other aspects of the microclimate in that location are greatly altered.
City planners should consider these matters thoroughly. One recent
state-wide conference on city and regional planning lasted for 5 days
and was attended by experts from all over the state. Yet not a single
word was mentioned about climate or about air pollution. Micro-
climate and man's influence on it were completely ignored.
ATMOSPHERIC STABILITY
Meteorologists work with charts called pseudoadiabatic charts
for analyzing the stability of the atmosphere. Lines on the chart
represent the adiabatic rate of temperature change with altitude. If
we force a layer of the atmosphere to rise, it will cool according to
this adiabatic rate as long as it is the free atmosphere away from in-
fluences of the earth's surface. Similarly, if we force a layer of the
atmosphere to subside or sink, it will warm according to the adiabatic
rate of the temperature change, which is about 5.4°F per thousand
feet. If the actual temperature lapse rate exceeds 5.4°F per thousand
feet, the atmosphere will be unstable. Since any slight vertical dis-
placement is capable of releasing this instability, it is extremely rare
to measure in the free atmosphere a lapse rate greater than 5.4°F
per thousand feet. When it occasionally happens, it does not persist
because the instability very soon results in convection and vertical
mixing, which realign the temperature distribution to a more stable
condition. In the boundary layer of the atmosphere, however, where
nonadiabatic heating takes place when the surface of the earth is
being strongly heated by the sun, the temperature lapse rate often
far exceeds our theoretical adiabatic rate of temperature change. If
we were to plot the distribution of temperature from the surface of
the earth upward, we would find an extremely rapid decrease of
temperature upward (assuming clear skies and strong heating of the
earth's surface by the sun) and then an alignment that more or less
parallels the adiabatic rate once we get 150 to 200 feet above the
64 HUMAN BIOMETEOROLOGY
-------
earth's surface. Theoretically we cannot have a lapse rate of this kind
for more than a brief instant because the atmosphere undergoes con-
vection and realigns itself according to a more stable temperature dis-
tribution. Actually, we can measure a lapse rate of this kind in the
lower few feet of the atmosphere on any bright sunny day with light
kinds; heat is being added to the surface layer of the atmosphere
more rapidly than it can be distributed by convection.
RADIATION
All the time that the earth is receiving solar insolation during
the daytime, it likewise is radiating some of this heat back into the
atmosphere and into space in the form of infrared radiation. As long
as our radiation balance at the earth's surface is positive, this type of
temperature distribution will prevail, with the surface layer of the
air being strongly heated. When the sun goes down, our radiation
balance changes signs. We have a negative radiation balance, and
the earth's surface cools rapidly. The earth is still radiating its
heat outward in the form of infrared radiation, but now nothing
is coming in. The temperature distribution undergoes a drastic
change, and temperature actually increases as we go upward
through the boundary layer under these circumstances. This is an
inversion of temperature, a reversal of the normal distribution. This
condition, so important in air pollution, is not nearly so rare as some
people believe. At the Brookhaven National Laboratory on Long
Island the study of micrometeorology in relationship to diffusion of
the atmosphere has been in progress for many years. Records of
hourly temperature observations, 24 hours a day, 365 days a year,
indicate that an inversion is present 44 percent of the time. Brook-
haven has level topography. In areas with steep slopes and sheltered
valleys, an inversion may be more common than the usual decrease
of temperature upward. Later we shall see an extreme example, in
which the persistence of a temperature inversion causes an inversion
of the vertical stratification of vegetation on the slopes.
ILLUSTRATIONS
Figure 1 is a plot of the mean daily temperature range against
wind speed. This figure shows a very clear relationship between wind
speed and the daily variation of temperature, again illustrating the
fact that strong winds tend to thoroughly mix the boundary layer of
the atmosphere and smooth out temperature differences not only from
day to night but from place to place. With light winds this effect of
the active surface in heating the lower layers of the atmosphere in the
daytime and cooling it at night has a much greater influence.
Figure 2, taken from Geiger's book "The Climate Near the
Ground," is an attempt to illustrate the effect not only of buildings
but also of dense forests in preventing the drainage of cold air down
slope in areas of hilly terrain. These two examples illustrate effects
of the natural and man-made environments on the microclimate.
Havens 65
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10
2.6
3.0
3.4
MEAN DAILY TEMPERATURE VARIATION, °C
Figure 1 Relationship between mean diurnal temperature range and mean wind speed on
clear days. (After Geiger)
Figure 2 — Frost pockets created by natural and man-made barriers to cold air drainage.
(After Geiger)
Figure 3 is another illustration along the same line but includes
isolines of minimum temperature showing the increase of temperature
with height, the typical nocturnal temperature inversion. In terrain
of this kind farmers have long been aware of this effect, and it is a
well-established agricultural principle that orchards and other crops
66
HUMAN BIOMETEOROLOGY
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that would be sensitive to frost injury or to low temperatures are
never planted in the bottom of a valley but on the slopes, so that cold
air can drain off. Temperatures usually do not go nearly as low on
the slopes as they do in the valley bottom because of this effect.
i-
i
120
no
100
STREAM
Figure 3 •— Isotherms of minimum temperature showing characteristic nocturnal temperature
inversion in valley. (After Geiger)
Figure 4 shows the alpine limestone cavity that I mentioned
earlier. Here we see —5°F near the ridge and •—49°F at the base of
the limestone cavity. This is actually a timberline in reverse, where
the vegetation at the bottom of the cavity is almost like tundra—
herbs and grasses—and only as we go up slope where temperatures
are warmer do we find trees.
Figure 5 shows a cross section of the Monongahela River at
Donora. As you probably know, an extensive microclimatological
survey of the Monongahela Valley at Donora was made after the
Donora air pollution disaster. This is the average temperature distri-
bution on calm days having relatively little smoke or pollution. You
see a temperature decrease as we go upward in the valley. Under
these circumstances convection and vertical mixing of the air would
minimize air pollution problems.
Figure 6 shows the temperature distribution in the Monongahela
Valley on a calm night with a very pronounced inversion. Tempera-
tures increased about 6 degrees or more from the base of the valley
up to the ridges on either side. Under such circumstances stagnation
of the air in the valley is to be expected and eventually can lead to
very serious difficulties.
Figure 7 illustrates the physical processes that result in drainage
of cold air into low places in the terrain. Once a sink of cold air in a
valley or in a pocket in the terrain is established, the temperature is
eventually reduced to the dew point so that fog forms. Then the solar
radiation, which we normally would count on to "burn off" our in-
version and create convection and mixing the following day, is simply
reflected off the top of the fog layer and so the inversion can remain
Havens
67
-------
throughout the day. At night (Figure 8) the fog layer acts as a
radiative surface and we have further cooling due to the loss of heat
by long-wave infrared radiation from the fog layer. Once this sort of
thing is established, whether in the Monongahela Valley or in the
vicinity of London, about the only correction for the situation is a
major change in the weather, a system moving in with strong winds
to clear up the problem.
150 m •• 492 ft
-2°F
~39° PASS LEADING TO
-47° LECHNERGRABEN
-47
-49°
-49° _49°F
CROSS-SECTION THROUGH THE GSTETTNERALM DOLINE
THE VERTICAL SCALE IS SOMEWHAT EXAGGERATED IN RELATION TO HORIZONTAL
DIMENSIONS.
Figure 4 — Pronounced nocturnal inversion due to cold air drainage into Gstettneralm
dolme. Vertical d.stnbution of vegetation is also inverted due to frequency, intensity, and
duration of temperature inversion. (After Geiger)
68
HUMAN BIOMETEOROLOGY
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O TESTING SUTO*
•1100
1000
wo
BOO
700
MEAN SEA
LEVEL
ELEVATION, ft
Figure 5 — Average temperature distribution across Monongahela Valley at Donora, Pa.,
on calm days.
O TESTING STATION
TOO
MEAN SEA
LEVEL
ELEVATION,ft
Figure 6 — Average temperature inversion in Monongahela Valley at Donora, Pa., on
radiation nights.
Havens
69
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AIR
Figure 7 — Diagram of manner in which radiatively cooled air descends into valley.
TtMttNATURE
HEIGHT CUM
Figure 8 — Role of fog in maintaining atmospheric stability and stagnation in valley.
70
HUMAN BIOMETEOROLOGY
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DISCUSSION
Question: What is the lowest inversion level that you could have
under some of these conditions?
Answer: Usually the inversion begins to form right around sun-
down, or in winter perhaps even a little earlier. It develops upward
as the night progresses. I think by sunrise with a clear sky and a
light wind the inversion usually will extend upward a minimum of
several hundred feet, sometimes as much as a couple of thousand feet.
Question: The reason I asked is that I've seen, particularly at
sunset, levels 20 or 30 feet above the ground where the smoke
levels off.
Answer: Right. At sunset or shortly after it is common for the
inversion to extend upward only a few feet or maybe 50 feet or so.
Above this you still have the normal decrease of temperature upward.
If you observe smoke plumes and other indications, you can quite
often see these effects. Under conditions of strong surface heating by
the sun, this decrease in temperature upward sometimes becomes so
extreme that peculiar refractions of light take place. The appearance
of water on the road in summer is one such effect. And the fabled
appearance of a mirage in the desert is another effect of this ex-
tremely sharp decrease in temperature upward immediately above the
earth's surface, which is being strongly heated by the sun.
Question: You mentioned this meeting of city planners. If you
had your micrometeorological druthers, what would you advise the
city planners on where to build their cities or their developments
within cities?
Answer: This isn't an easy task, but certainly some attention to
the microclimate in planning is far better than simply ignoring the
problem. We should consider both the microclimate of the immediate
vicinity in relationship to terrain and also the large-scale aspects of
the microclimate. Certainly to put the stockyards upwind from the
residential section, as has happened in certain cities in this country,
is not very good planning. We know a lot about the prevailing winds
in various parts of the country. The Weather Bureau has enormous
amounts of climatological data at the National Weather Records Cen-
ter at Asheville. Summaries of these data are available, and planners
could have ready access to this material. We know less about the
microclimate in and around many of our large cities and other urban
and suburban areas. But even without measurements, qualified
meteorologists should be able to give qualitative estimates of micro-
climatic effects on the basis of terrain and other features. With a
little bit of effort some data could be collected to put some of these
estimates on a quantitative, rather than a strictly qualitative basis.
SELECTED REFERENCES ON MICROCLIMATOLOGY
1. Brooks, F. A. An Introduction to Physical Microclimatology. Univer-
sity of California, Davis.
Havens 71
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2. Franklin, T. Bedford. Climates in Miniature. Philosophical Library,
New York. 1955.
3. Gates, David M. Energy Exchange in the Biosphere. Harper and Row,
New York. 1962.
4. Geiger, R. The Climate Near the Ground. Harvard University Press,
Cambridge. 1965.
5. Pacquill, F. Atmospheric Diffusion. D. Van Nostrand Company, Ltd.,
London. 1962.
6. Priestley, C. H. B. Turbulent Transfer in the Lower Atmosphere. Uni-
versity of Chicago Press. 1959.
7. Sutton, O. G. Micrometeorology. McGraw-Hill, New York. 1953.
8. Meteorological and Geoastrophysical Abstracts. American Meteorolog-
ical Society, Boston.
Vol. Ill, No. 7, Bibliography on Urban Climatology. 1952.
Vol. IV, No. 8. Radiation Bioclimatology. 1953.
Vol. VII, No. 2. Climate of Enclosed Spaces. 1956.
Vol. VIII, No. 11. Medical Meteorology. 1957.
72 HUMAN BIOMETEOROLOGY
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THE NATIONAL WEATHER RECORDS CENTER
Dr Harold L. Crutcher
National Weather Records Center
Federal Building
Asheville, North Carolina 28801
SUMMARY
The National Weather Records Center (NWRC) provides cen-
tral storage of weather data in punched card or microfilm form at
Asheville, North Carolina, (the equivalent of about 450 million
punched cards processed as card decks) and includes data from the
Meteorological Rocket Network and from the first atomic-powered
automatic weather station at Sherwood Head, Canada. Available to
anyone at the cost of reproduction (microfilm, photocopy, Xerox,
microprint, etc.) are data in the form of hourly, daily, and monthly
summaries giving information on solar radiation, winds aloft, radio-
sonde significant levels, and absolute humidity.
INTRODUCTION
During World War II years it became apparent to all those who
were dealing with climatology or meteorological research that a
central locale for the storage of weather data really was needed.
In those days if a man wanted some weather data for his research,
he wrote to the meteorologist in charge of a weather station; if the
records were there, the meteorologist in charge might or might not
send them out. As research goes on, records sometimes become mis-
placed and are not returned. At Washington National Airport, 3 months
of records are missing from the permanent files. The data were
needed to study a special storm situation. These were never returned
and now are forever lost to our nation's records.
During the war years the New Orleans group, which was then
called the New Orleans Tabulation Unit, wrote to all the weather
stations to get data for wartime studies. They encountered the same
problem. As a result of that experience and through the developing
meteorological research facilities of the Weather Bureau, the Air
Force, the Navy, and universities, it became apparent that a central
locale was needed. In 1948 officials started looking for a place, and
in 1951 the site in Asheville became available.
ESTABLISHMENT OF CENTER
The General Services Administration delegated to the U. S.
Weather Bureau the responsibility to archive the weather reports
of the U. S. Weather Bureau, the Air Force, and the Navy, and any
Crutcher 73
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other national weather records that could be obtained. With con-
siderable help from the Air Force and the Navy, both financial and
physical, the U. S. Weather Bureau established the National Weather
Records Center in Asheville in 1951 and 1952.
The National Weather Records Center (NWRC) is housed in a
Federal Building formerly known as the Grove Arcade. The NWRC
is within 24 hours reach from Washington by most modes of trans-
portation. It is within 24 hours reach from the major cities of the
U. S. by plane. Many of our requests are from lawyers who need
weather records or certified facsimiles for accident cases. Usually
the records are on the way to the requester within an hour or two
after he calls. If the airlines are operating he usually has them within
24 hours.
The Federal Building is located in downtown Asheville. It covers
half an average city block and averages four stories in height. The
space totals about 225,000 square feet, of which about 165,000 is
usable. The files contain some 100,000 cubic feet of original records
and publications, several thousand reels of magnetic tape, and the
equivalent of about 450 million punched cards. The millions of
punched cards are handled systematically by assigning deck numbers
to cards having like format and content. Some 350 card decks are
now available for use in processing of data. Some decks have become
obsolete and have been destroyed. We also have foreign data cards.
CAPACITY
The total card volume at Asheville has been greater than it is
now. But right now storage of the cards requires a row of filing
cabinets one tier high and almost 2 miles long. If all the trays of
cards were laid end to end, they would extend 50 miles. Through
transfer and microfilm reduction, we have reduced our card holdings
in Asheville to 350 million cards. If we had not reduced our storage,
we would have almost 600 million cards, all occupying precious space.
We receive copies of punch cards from the Meterological Rocket
Network. The handling of the weather satellite photographs and of
radiation measurements is under continual development. We also
receive magnetic tapes from the satellite observations.
The NWRC has operational responsibility for the Meteorological
and Nuclear Radiation data for World Data Center A, initiated under
the International Geophysical Year, and has on file records from the
first atomic-powered automatic weather station at Sherwood Head,
Northwest Territory, in Canada.
New sensors and recording methods will continue to appear. As
they appear and give new types of records, we will have to develop
new types of storage and servicing. We hope to keep pace with this
changing input of data and to provide support to persons interested
in meteorological research. Scientific measurements do not lose their
74 HUMAN BIOMETEOROLOGY
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value with age, as do cancelled checks, administrative forms, and
inter-office correspondence. No one can predict when any of these
records will be much in demand. A speech at a convention may
spark a lot of ideas. These ideas develop in men's minds and the
researchers begin to call for data. We may have to go back 50 years
for data from some locale, and face a sudden demand for records
that have not been called for or used in decades.
RECORDING TECHNIQUES
The NWRC now uses the FOSDIC machine—the Film Optical
Sensing Device for Input to Computers. This is our best hope for
keeping ahead of our space problem. Using two filmers, we have
placed approximately 130 million punch cards on microfilm. We
microfilm these cards with the holes in them on 16-mm microfilm.
Each 100 feet of film contains 12,000 card images, 12 to the inch.
The microfilm reduction is better than on magnetic tape. It is also
much cheaper, because magnetic tape must be updated at least every
3 years because of the magnetic image transfer between layers of tape
wound on the reel. So we use the microfilm as a positive type of
storage that can be easily duplicated by making copies. Copies of
these microfilm records are being stored in salt mines and other
places where they will be safe from catastrophe. Use of microfilm is
a relatively cheap way of storing data. I say "relatively" cheap
because all of these methods are expensive since the magnitude of
data storage is so great.
The horizontal reduction of these cards is 24 to 1, and the vertical
reduction is 44 to 1. That reduction permits us to place an image of
that punch card in l/12th inch of space. Four card trays—trays
about 2 feet long and 8 inches wide, each containing 3,000 cards (a
total of 12,000 cards)—can be placed on one reel of 100 feet of micro-
film. This film reduces to a box 1 by 4 by 4 inches and weighs only
4 ounces.
You may ask why we microfilm these cards, since it would be
difficult to read them through a lens system. But we do not read
them through a lens system by eye; we read them by means of a
cathode ray follower. We can recover the cards through this optical
reader, the FOSDIC reader. The punch card contains 80 columns
and 13 horizontal rows. The reader can search 10 columns at a time
at a rate of 4,000 cards per minute and select those cards that have
the pieces of weather information that you want to use. New cards
can be punched at a maximum rate of 100 per minute. Equipment
that will provide a faster recovery rate is under development through
a coordinated program with the Census Bureau, the Bureau of Stand-
ards, and the Weather Bureau. The reader will read 8,000 cards per
minute, search 10 columns, identify the columns, and check for ac-
curacy of punches. It will do all of this at 8,000 card images a minute
and transfer 2,000 of these to magnetic tape, which then can be trans-
ferred as a working medium into computers.
Crutcher 75
-------
We have many types of cameras at the NWRC to reduce our
original documents to microfilm. We save all documents, since every
piece of government paper is government property and becomes a
part of the archives of the records of the United States. Before we can
destroy a weather record we must obtain Congressional approval,
and to do this we must show that we have not lost the record. About
the only way we can do it is to microfilm the records. One of the
cameras under development will photograph a continuous flow of
forms once you've set the camera and the stages for the same type of
forms—for example, rain gauge charts or wind records. It will handle
these forms like a printing press and run them onto a table, place
them in position and automatically photograph them. The film used in
this camera is 70 mm wide and comes in 100-foot rolls. These can be
left in the roll or chopped into 3 by 5 negatives and stored like micro-
cards, which then can be reproduced in negative form or positive form.
COMPUTING FACILITIES
The computing facilities of the NWRC are headed by a Honey-
well 800, a parallel processing machine that is module designed. As
the requirements increase, the memory and capacity of this machine
can be upgraded by adding more memory blocks or by adding
peripheral equipment. The system can process eight jobs at a time.
The only restriction is that we can't use the central memory on more
than one job at the same time. For example, we may have a large
scientific job that requires many computations. We can do card
editing, tape editing, and punchout, and printing of other jobs on the
side while the central memory works on the scientific job. As soon
as it's through with one phase of the job, the central memory flips
over to another job. At present we only have four of these input
devices, but the system can handle eight if we add four more sets of
peripheral equipment. Of course, all of these are supported by other
types of electrical accounting machines, such as sorters, collators,
tabulators, reproducers, and the electronic calculator.
DATA DESCRIPTION
I have tried to give you some ideas of the physical building and
the equipment in the building. Now I want to discuss in more detail
some of the types of data that are available to those engaged in
research.
First of all, the punch card can be considered only as working
media. These are not original records, although in some cases these
constitute our only holdings of data. For example, we may have
received cards from some foreign government on an exchange basis
or by trade, in dollars. The German marine deck—about 7 million
cards—was purchased in 1952-54, when we initiated the Marine Atlas
program for the U. S. Navy. These, of course, constitute our only
holdings of data of that type because the original manuscripts are
still held in the archives of the German Naval Weather Service.
76 HUMAN BIOMETEOROLOGY
-------
PHOTOGRAPHIC IMAGES
Original manuscript forms or some reduction of these to photo-
graphic images constitutes our main source of data. These are avail-
able to anyone at the cost of reproduction, which may be in the form
of microfilm, photocopy, Xerox, microprints, microcards, or other
type. For forms that use color, such as adiabatic charts for the upper
air data, microfilm techniques certainly do not do the job we would
like to do. And the adiabatic charts contain so much information that
reduction by microfilm loses some of the detail.
PUNCHED CARDS
The punched cards constitute our second largest mode of data
storage. About 350 card decks have been documented and a reference
manual prepared for each one. The reference manual lists every
column in the card and describes the codes used to place data in those
columns. Wherever possible we try to give further information about
the data. For example, in the coding of inversions we try to draw
diagrams for people who will use the data. Since the reference
manuals sometimes omit needed information, we must often revise
or supplement the reference manual.
Each project requires considerable time and care to develop a
reference manual.
Many people want to buy cards for use with a computer in their
own organization or one available by contract with a service organi-
zation. But about half of the people who purchase cards for their
own processing run into difficulties with the coding. These X over-
punches can mean many, many things.
Not everyone who prepares cards for weather data will handle
certain peculiar problems in the same way—problems such as the
indication of minus temperatures or of wind speeds higher than 100
knots. Also, the presence of a space for a weather element on a card
does not guarantee that the element will have been observed and re-
corded at a specific station at a specific time. The reference manual
cannot tell you whether the data are there, only that the card has
space for such an observation if it was made and recorded. Then
too, since changes in operating procedure entail changes in coding
procedure, such changes must be carefully watched for in pro-
gramming for the punched cards.
Let me give you an example of the programming complexities
caused by changes in the operation of weather stations. The example
concerns the reporting of upper-air data. At different times in recent
years wind speeds have been reported in meters per second, in knots,
and in miles per hour. Wind directions have been reported at 8, 16,
and 32 points of the compass and are now reported in degrees. These
changes in reporting procedures were made on different dates. In
researching upper-wind data through the years, therefore, you must
be aware of the modes of reporting so that you can perform any con-
Crutcher 77
-------
versions required to produce data in uniform or comparable units.
We know that operating procedures are determined by meteorologists
for their professional purposes; considerations of data-keeping are
secondary. Our job, then, is to adjust to the changes and to keep the
cards and programs current.
CONCLUSION
It would be difficult to describe to you the many and diverse
kinds of weather records that are available. We have decks that
provide daily summaries, monthly summaries, hourly records of solar
radiation, winds aloft data, and, for those who are interested in air
pollution, a deck of radiosonde significant levels that gives informa-
tion on inversions. For biometeorologists the records of absolute
humidity (mass per volume) are of interest because the lung is a
volumetric machine. Data on absolute humidity have been used in
polio investigations. These can be backed up by data on other humidi-
ties: relative humidity, specific humidity, and mixing ratio.
All of these and many other potential sources of information are
available to you. I hope I have given you some idea of the magnitude
of the operation at Asheville and of what the National Weather
Records Center offers to aid in your research.
DISCUSSION
Question: How do you indicate the geographical area to which
the data apply?
Answer: We use the international block system. It is a grid
system on the map that has been arbitrarily fixed by national and
international boundaries. For marine data, the 10-degree squares
called Marsden squares are broken down further into sub-squares
of 5 degrees, and then down to 2 degrees and 1 degree, and further
on down to tenths of degrees in some cases for the ocean areas. For
continental areas we use an initial block number.
Question: And these are your own maps, not the U.S.G.S. maps
for the transverse Mercator projection?
Answer: These maps are developed and agreed upon by the
international World Meteorological Organization.
Question: How does one obtain the reference manual that tells
of your card formats and the changes?
Answer: Well, first you must know what reference manual you
want. We don't send these out to everybody. We use them more as
an inshop work manual. Many people and organizations do buy data
in cards, and when they buy them we send a reference manual. We
have 350 active decks now, and that means 350 reference manuals.
If you want to know what's in the cards and you know that a refer-
78 HUMAN BIOMETEOROLOGY
-------
ence manual is available, then we would send that to you for study
along with a sample card. We have had people ask us for a copy of
every card and reference manual made. We asked them if they would
pay the shipping costs; when it turns out to be $100.00, they say, "No,
thank you."
Question: We have a little bit of difficulty in finding the Asheville
code number for meteorology stations. Is there a list of these code
numbers available?
Answer: Yes. There is a code manual for that. This manual is
kept current with the assignment of new stations and with the assign-
ment of new code numbers. This code manual is not exactly a pub-
lication. It is a work listing which is kept up to date at the National
Weather Records Center. Relatively few copies of this listing are
available outside of Asheville. The reasons for this are that there
are frequent additions of stations to the listing, and that these num-
bers are peculiar to the processing operations at Asheville—they are
not used in any other sense in the meteorological circle. This is not
the international index number assigned and coordinated by the
World Meteorological Organization. This is purely a work number,
and therefore it is a work manual. We discourage requests for copies
of this manual. Whenever we send a listing of data run from our
card decks, if there is no literal identification of the station by name
on each page of the listing, the station is identified by its number.
We send a flysheet that translates the number to the name of a sta-
tion, so that the stations are identified. When you purchase copies
of cards, however, we send some descriptive material so that you can
identify the particular number of a particular station.
Crutcher 79
-------
SOME EFFECTS OF WEATHER ON MORTALITY
Mr. Paul H. Kutschenreuter
Environmental Science Services Administration
Rockville, Md., 20852
SUMMARY
Temperature is the most significant meteorological parameter
in the study of mortality and weather. Studies have shown (1) a
general inverse seasonal relationship between temperature and death,
(2) an identifiable seasonal response in all age groups except age
group 1 to 25; (3) significant correlations between total monthly mor-
tality and average temperatures for winter and summer months, but
not spring and fall; and (4) significant correlation in data from
studies using "heat-death-line" and those using "temperature-
humidity-index" criteria. A study of 17 periods from 10 summers of
record in New York revealed a significant increase in mortality fol-
lowing a hot spell and/or severe fluctuations in weather.
INTRODUCTION
The material presented here is based on graduate work(4) done
at Rutgers University in 1959. The initial study included 9% years
of statistical data on New York City mortality by age groups. These
data were recorded on a daily basis by the Department of Health,
City of New York, for the date on which the death actually occurred,
beginning in June 1949. This symposium has provided the incentive
to obtain subsequent data for comparison with the various regression
analyses determined from the developmental data.
WEEKDAY VARIATIONS
The data were examined initially to determine whether there
were any significant weekday variations that should be taken into
account before making correlations with meteorological statistics.
Table 1 presents the average weekday mortalities by age groups.
These are nearly identical except for the Sunday minimum of 219.1
and the Monday maximum of 227.4. Since meteorological studies
have not yielded any statistically significant 7-day periodicities, it
was concluded that the Sunday mortality minimum and the Monday
mortality maximum were attributable to sociological rather than
meteorological factors. Further, neither the maximum nor the mini-
mum was significant at the 5 percent level selected as a measure for
statistical significance. For the purposes of this study no weekday
corrections were required.
Kutschenreuter 81
-------
Table 1. AVERAGE DAILY MORTALITY
Age group
1
1-4
5-14
15-24
25-44
45-64
65-over
Total
Sun.
10.8
1.6
1.3
2.3
16.2
72.9
114.1
219.1
Mon.
11.0
1.8
1.4
2.3
16.7
77.6
116.6
227.4
Tues.
11.1
1.8
1.4
2.1
16.5
73.8
115.1
221.8
Wed.
10.9
1.6
1.4
2.3
16.2
74.0
114.5
220.9
Thurs.
11.5
1.7
1.5
2.3
16.4
73.8
114.7
221.8
Fri.
10.9
1.8
1.4
2.3
16.4
73.7
114.7
221.1
Sat.
11.2
1.8
1.4
2.5
16.8
74.1
113.3
221.0
SEASONAL RELATIONSHIPS
Gordon and Ehrhardt(2) indicated the general inverse seasonal
relationship of temperature and death, illustrated in Figure 1. For
comparative purposes I have also included in Figure 1 the annual
total mortality and annual normal temperature curves for Los Angeles
and Cincinnati. Tromp(6) has shown the same seasonal relationship
in curves for mortality from angina pectoris, coronary thrombosis,
and other arteriosclerotic heart diseases and from chronic endocarditis
among males in the Netherlands in the years 1953-1958, inclusive.
The annual mortality curves for each of the age groups are given
in Figure 2. These curves may be divided into two separate and
distinct categories: those that exhibit a pronounced seasonal trend
and those that exhibit no readily identifiable seasonal response. This
seasonal response is evident in the infant category, disappears en-
tirely in the age groups from 1 to 24 years, reappears in the group
from 25 to 44 years, and becomes more pronounced with increasing
age.
Since the seasonal mortality trend -is evident in the infant group
but disappears entirely in the next three age groups, it was at first
suspected of being a pseudoclimatic effect, perhaps due to a corres-
ponding seasonal difference in birth rates. This, in turn, would give
rise to a corresponding seasonal variation in infant population and
hence also in infant mortality expectancy. The birth-rate statistics
for this period failed to indicate any significant seasonal trend, how-
ever. It, therefore, appears that the seasonal mortality response
among the infant population is an indirect effect, due to colds and
other infectious diseases passed along to the infant from susceptible
adults. This would also account for the disappearance of the seasonal
trend after infancy.
The top panel of Figure 2 shows a pronounced change in the
mortality curve between the 1900-1911(3) and current data. The
very pronounced secondary maximum in July in the earlier data
disappeared entirely in the later data. Examination of New York
82
HUMAN BIOMETEOBOLOGY
-------
mortality statistics following the turn of the century indicates that
this secondary maximum was contributed by the younger age groups,
especially those in the 1- to 4-year category. This summertime max-
imum is an example of "Suedosaisonkrankheiten" (pseudo-seasonal
illnesses) mentioned by De Rudder (I). It was attributed to stomach
and intestinal disorders resulting from food spoilage due to lack of
adequate refrigeration during hot weather—an indirect influence of
weather on mortality. This secondary maximum was eliminated with
the subsequent availability of pasteurized milk and with adequate
refrigeration as modern electric refrigerators replaced the less ade-
quate "ice boxes."
J FMAMJ JASONDJ FM
X
^Normal Temperatures s
J J A S
MONTH
Figure 1 — Annual mortality curves for New York City, Los Angeles, and Cincinnati.
Kutschenreuter
83
-------
260
240
220
200
130
120
110
100
£M
-------
gave an opportunity to consider whether the color of one's skin or
ethnic background might have any bearing on his reaction to weather
and severe changes. The respective curves for the seasonally re-
sponsive age groups are shown in Figure 3. There are no significant
differences m the characteristics of the two sets of curves Neither
were there any detectable differences in reaction to hot spells as
shown later.
Non-
nit« Whitel
230 26
220 25
210 24
200 23
190 22
180 21
130 8
^ 120 7
110 6
70 ,0
65 9
60 8
12 5.0
11 4.5
10
MONTH
A M J J A
1 I 1 I T
/ ^
"NDJ FMAMJJASONDJ
Total While
Total Non-White
65 And Over .White
65 And Over, Non-While
i45-64,White
45-64,Non-White
25 44,White
25-44 Nan.Whin
Figure 3 — Annual mortality curves for white and non-white.
Kutschenreuter
85
-------
Maximum mortality in the white group, however, occurs at age
65 and over, whereas in the non-white group it occurs at ages between
45 and 64. This shorter life expectancy among the non-whites has
been attributed to sociological factors and to environmental factors
other than meteorological. Accordingly, no detailed effort was made
to explain it from a meteorological standpoint.
COMPARISON BY MONTHS
Next, total monthly mortality and average temperatures for the
same months were compared. As might be expected from Figure 1,
no significant correlations are evident for the spring and fall transi-
tion periods but significant correlations are found for the winter and
summer months. Computed correlation coefficients for the susceptible
age groups and for significant months are given in Table 2. Months
with a high incidence of influenza were excluded from these compu-
tations on the basis of being outside the "normal" population under
study. Note the very high correlation coefficients for December
(minus 0.74) and for January (minus 0.96). The latter is significant
at the level of 0.1 percent.
Table 2. MONTHLY MORTALITY AND AVERAGE
TEMPERATURE, CORRELATION COEFFICIENTS
Month
Jan.
June
July
Aug.
Dec.
d.f.
8
9
9
9
8
Age group
25-44
r
0.859
0.196
0.317
0.206
0.342
%
1
—
—
—
—
45-64
r
0.509
0.583
0.581
0.306
0.232
%
—
6
6
—
—
65 -over
r
— 0.933
0.257
0.384
0.144
—0.568
%
0.1
—
—
—
7
Total
r
— 0.958
0.670
0.673
0.541
— 0.740
%
0.1
5
5
—
2
d.f. = degrees of freedom
r = correlation coefficient
% = level of significance
— => 10%
Figure 4 shows the computed regression curves. The individual
dots represent the 1949-1958 data, which were used in developing the
regression equations. How do the mortality figures for 1959 through
1963 fit the regression curves? These independent data points are
shown on the graphs as crosses.
The independent data for December and January show approxi-
mately the same slope as the regression curves based on the earlier
data, but displaced upward by a significant amount. A noteworthy
exception is the one January value that appears to be completely out
86
HUMAN BIOMETEOROLOGY
-------
of control. It was at first suspected that this extreme value might be
due to a high incidence of Asian influenza. Although this did not
qualify as an "influenza month," the incidence of other respiratory
ailments was very high. Such ailments are suspected of being
weather-related to the extent that the stability of the lower layers
of the air governs the concentration or dispersal of airborne irritants
and pollutants. The relationship is much more complex than the
simple temperature-mortality relationship examined here. The gov-
erning meteorological factors are well known, however, and provide
the basis for the air pollution potential forecasts performed by the
Weather Bureau in cooperation with the Public Health Service.
49'
40*
45'
40-
U. 30'
Ul
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45'
40"
35'
30*
25"
g
LU
70OO 7ZOO 740O 70OO 7BOO 80OO 820O 840O 860O 88OO 9OOO
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MOO 6OOO 62OO 64OO 68OO MOO 7OOO 72OO 74OO 70OO 780O
TOTAL MONTHLY MORTALITY • = Initial (developmental) data
X = Subsequent (independent) data
r = regimen
Figure 4 — Regression of total monthly mortality on monthly average temperature.
Kutschenreuter
87
-------
The apparent upward shift in the January and December re-
gression curves is readily accounted for on the basis of a gradual
increase in life expectancy during recent years. This has resulted in
a gradual increase in the population of the 65-and-over age group,
in which the highest mortality occurs. The downward shift of the
independent data for June through August, though not as pronounced
(since the correlation coefficients were not as high), is similarly
explainable.
DAILY TEMPERATURE VARIATIONS
The temperatures on which these correlations were based were
averages for the month. Still another test was a comparison of mor-
tality with daily departure from normal temperature. Comparisons
made on this basis indicated that although a large departure from
normal temperature (particularly in the summertime) might be a
necessary condition for high mortality, it was not a sufficient condi-
tion.
DISCOMFORT
A number of authors have reported on studies concerning heat
discomfort and heat death. Elizabeth Schickele(S), for example,
made a study of heat deaths during World War II and on a scatter-
gram drew what she referred to as a "heat death line." Of 265 heat
deaths, all but 7 occurred on the upper side of the heat death line.
During the summer of 1959 the U. S. Weather Bureau began
publishing a figure that includes the combined effects of temperature
and moisture. This was first called the "Discomfort Index," and later
the "Temperature-Humidity Index" (THI), which is still used in
many locations. It was determined that whenever the THI is less
than 70, practically everyone feels comfortable. At THI 75, at least
half the people are uncomfortable. Above 75, discomfort rises very
rapidly and acute discomfort is experienced by the time the figure
reaches the middle 80's.
A comparison of Schickele's heat-death line and lines of constant
THI is shown in Figure 5. Although the approaches used in develop-
ing these two concepts differ, the lines become parallel in the critical
mid-80 THI region. Further, the heat-death line runs its course
within the important, THI region of 75 to 85.
EXTREME HEAT
Figure 6 shows the running weekly mortality curve for New
York City in 1957. Such curves are maintained on an up-to-date
basis by the Department of Health and are based on 5-year, 5-week
moving averages. The shaded area is the plus or minus 2 standard
deviation "tolerance zone." In addition to the exceedingly high mor-
tality averages attributed to Asian influenza in October and early
88 HUMAN BIOMETEOROLOGY
GPO 801—494—4
-------
November, there are two noteworthy maxima in the summertime
when normally the expected mortality is quite low. One of these
has been labelled "3 days severe heat."
HIGH INCIDENCE OF HEAT DISEASE/.
• • • RAPID INCREASED . « .
".OF DISCOMFORT IN THIS AREA*.
THI =Temperoture humidify inde
Heo I death line
50 60
DEWPOINT, °F
70
80
90
Figure 5 — Temperature humidity index {TH1J and heat death line.
Accordingly, I decided to examine the correlation between New
York City mortality and weather during "hot spells." For the purpose
of this study, a hot spell was denned as:
1. Three or more consecutive days with 3-day mean de-
parture from normal — 5°F.
Kutschenreuter
89
-------
2. At least one day with a departure from normal (actual
departure, not 3-day mean) - 10°F.
3. The 3-day mean departure from normal remains positive
throughout the period.
4. The maximum temperature exceeds 90° on at least one
day.
5. The hot spell begins on the first day the 3-day mean
departure is — 5° and ends on the first day the 3-day
mean departure is - 5° and remains - 5°
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MONTH
Figure 6 — New York City mortality chart for 1957.
90
HUMAN BIOMETEOROLOGY
-------
From the 10 summers of record on which this study is based, 17
periods qualified as hot spells in accordance with the criteria.
In examining the mortality figures for the individual hot spells
we note immediately that the mortality increased significantly on
the day following the first hot day and continued rather high over a
3-day period. Accordingly, 3-day running mean departures from
normal temperatures were compared with 3-day running mean values
for total mortality, but with mortality figures lagged 1 day behind
the normal temperature departures. Graphs for four of the more
phenomenal of the 17 hot spells are shown in Figures 7 and 8. For
comparison, graphs for five of the less-pronounced hot spells are
shown in Figure 9.
340
320
300
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1-
220
200
180
UJ
1C
O
O
UJ
Ct
/ \-
\
-Normal Temperature
10
12 14 16 18
DAY OF MONTH
20 22
24 26 28
30
Figure 7 — Time series graphs for rwo July 1955 hot spells.
Kutschenreuter
91
-------
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92
HUMAN BIOMETEOROLOGY
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DAY OP MONTH
Figure 9 — Time series graphs for several letter hot spells.
Note particularly Figure 8. The initial hot spell lasted only 4
days. It was immediately followed by temperatures considerably
below normal and equally rapidly by an even more intense hot spell.
The temperatures and winds for the 13-day period are shown in the
tabular insert. These extreme temperature fluctuations exacted a
correspondingly heavy death toll.
The body strain resulting from such extreme fluctuations was
so severe as to cause a rise in mortality even as the temperature was
still falling. The subsequent 100° maximum temperature on June 26
was followed by a record high mortality of 542 on the following day.
This is very nearly 3 times the expected mortality. It exceeds the
mortality for any other day in the 9%-year period—higher than the
mortality even at the height of the Asian influenza epidemic.
Further examination of daily mortality during the summer
months yielded still another significant feature: minimum daily mor-
tality for the month occurred very shortly after the end of a hot spell
in every instance but one. The minimum occurred 2 days before the
beginning of the hot spell in July 1957. Of the remaining 11 months
that had hot spells during these 10 summers, the minimum mortality
occurred on the day following the end of the hot spell in two cases,
on the second day in three cases, the third day in one case, four days
and six days later in two cases each, and eight days later in one case.
Kutschenreuter
93
-------
Two likely contributory factors may explain minimum mortality
following the hot-spell maxima. One is the invigorating effect of
cooler temperatures following a hot spell. That this effect can be
carried to extremes and then actually reversed, however, is evident
in the increasing mortality rate during the relatively "cold" period
between the two June 1952 hot spells (Figure 8). The other contri-
butory factor is the likelihood that the excess casualties during hot
spells consist to a major extent of those who normally would have
passed away on succeeding days.
ANALYSES
Linear multiple regression analyses were run for all 17 hot
spells. Mortality was the dependent variable. Six meteorological
parameters (departure from normal temperature, maximum temper-
ature, wind, THI, relative humidity and barometric reading) were
the independent variables. As was expected, temperature was by
far the most significant parameter, and barometer reading not sig-
nificant at all. For the two older age groups (45 to 64 years and 65
and over), temperature alone was significant at about the 0.1 percent
level or better, both for white and nonwhite. Correlations for all
parameters and all age groups are contained in considerable detail
in the original thesis material available at Rutgers University. (4)
REFERENCES
1. De Rudder, B. Grundriss Einer Meteorobiologie des Menschen.
Springer Verlag, Heidelberg. 1952.
2. Gordon, John E., and Ehrhardt, Carl L. Weather and Death. Amer.
Journal of Med. Sci. 236, No. 3: Sept. 1958.
3. Huntington, E. Temperature Optima for Human Energy, Proc., Natl.
Acad. of Sci. 3: Feb. 1917.
4. Kutschenreuter, Paul H. A Study of the Effect of Weather on Mortality
in New York City. M.S. Thesis, Rutgers University. January 1960.
5. Schickele, Elizabeth, Environment and Fatal Heat Stroke, The Military
Surgeon, 100, No. 3: March 1957.
6. Tromp, S. W. Monthly Mortality from Apoplexy, Angina Pectoris,
Coronary Thrombosis and Related Heart Diseases in the Male and
Female Population in the Netherlands. Bioclimatological Record Cen-
ter, Leiden. 1959.
94 HUMAN BIOMETEOROLOGY
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HEAT STRESS
Dr. Austin F. Hensefael
Occupational Health Research and Training Facility*
U. S. Public Health Service
1014 Broadway
Cincinnati, Ohio 45202
SUMMARY
Man meets the problems caused by internally generated meta-
bolic heat and externally imposed environmental heat by 'means of
physiological mechanisms such as vasodilation and sweating to in-
crease heat loss not obtained by normal heat exchange by conduction-
convection and evaporation-convection. Important -factors in the
effect of heat on man are humidity, radiant energy exchange, air
temperature, and air movement. The -four major categories of heat-
induced illnesses (heat exhaustion, dehydration, heat cramps, and
heat stroke) are discussed.
INTRODUCTION
Problems that confront man when he is exposed to a hot environ-
ment and physiological mechanisms he utilizes to cope with the
problems are discussed in this section.
Two kinds of heat important to man working or living in a warm
•or hot environment are: internally generated metabolic heat, and
externally imposed environmental heat.
Metabolic heat is a byproduct of the chemical processes occurring
within the cells, tissues, and organs. Under resting conditions the
metabolic heat production of an adult is about 75 KgCal per hour
(300 Btu). Muscular activity is the major source of increased heat
production. During very hard physical work heat production may
reach 600 to 750 KgCal per hour (2,400 to 3,000 Btu). Thus under
conditions of physical work large quantities of heat must be removed
from the body if an increase in body temperature is to be prevented.
An internal body temperature of 99 °F (98.6°F mouth tempera-
ture) is usually considered to be "normal"; however, body tempera-
ture varies from time to time during the day and with changes in
physical activity. Consequently body temperatures of 97° to 102°F
are frequently normal. Body temperature over 102°F in otherwise
healthy individuals must be viewed with some concern, and a tem-
perature over 105°F is critically serious. Consequently, the regula-
tion of body temperature is an important physiological function, and
*Now part of the National Center lor Urban and Industrial Health.
Henschel 95
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the ease with which it can be successfully accomplished is determined
by the individuals' ambient environment—by the air temperature,
the humidity of the air, air movement, long-wave radiation, and
solar radiation.
HEAT EXCHANGE
The metabolic heat of the body is exchanged with the ambient
environment by the processes of conduction-convection, radiation,
and evaporation. If the contact substance, whether it be air, water,
clothing, or an external object, is at a lower temperature than the
skin, heat will be lost; but if the contacting substance is at a higher
temperature, heat will be gained. The rate at which transfer takes
place is determined basically by the difference between the two
temperatures, but if the contacting substance is fluid, like air or water,
movement in the fluid accelerates the transfer. This additional
transfer process is termed convection.
HEAT TRANSFER BY CONDUCTION-CONVECTION
Nearly all transfer of "sensible" heat between skin and air is by
the combined process of conduction-convection, in which convection
plays by far the greater part and may be expressed quantitatively
by the equation:
TT Kc (ts — t,,)
^=-~i7+ir- (1)
where:
HL. = the rate of heat loss per unit area of exposed surface,
Kc. = a constant whose value depends upon the units used.
ts = the temperature of the skin surface.
tn = the temperature of the ambient air.
In = the resistivity of the ambient air to the outward passage of
heat.
Ic = the resistivity of the clothing to the outward passage of
heat.
To this exchange between the skin and the air must be added
heat exchanged between the respiratory tract and the inspired air,
since the former behaves simply as an inward extension of the body
surface, with a special mechanism—respiration—moving the air away
when it is heated.
HEAT LOSS BY EVAPORATION — CONVECTION
Heat may also be lost from the surface of the body to the air by
evaporation of water diffusing through the skin from deeper tissues,
produced by sweat glands, or applied from without. The rate of
evaporative heat loss is determined basically by the difference be-
tween the effective vapor pressure of the water on the skin and that
96 HUMAN BIOMETEOROLOGY
-------
of the air, but once again movement of the air greatly accelerates
the rate of loss, so that the combined process is properly termed evap-
oration-convection.
The vapor pressure of water on the skin is determined by the
temperature of the skin, but the extent of the water film varies be-
tween something less than 10 percent and 95 percent of the maxi-
mum. The effective vapor pressure of water on the skin is thus a
function of these two factors. The extent of the water film is variously
termed "skin wetness" or "skin relative humidity." It represents a
balance between evaporation on the one hand and addition of water
on the other. It is high only when the sweat glands are active, evap-
oration is inhibited, or water is applied from without.
HUMIDITY
The vapor pressure of the air is determined by the amount of
water vapor present in (unit volume of) the air and corresponds
closely to the absolute humidity of the air. Unfortunately, atmos-
pheric humidity is usually expressed in terms of relative humidity,
namely, the ratio between the amount of water vapor actually in
the air and the amount the air could hold at that temperature. To
determine the vapor pressure from the relative humidity, one needs
to know the air temperature and to have tables or a graph by which
to make the conversion. A great deal of misunderstanding and con-
fusion has arisen from the use of these two measures of atmospheric
humidity, between which the relationships are far from obvious. A
vapor pressure of 15 mm Hg corresponds to 100% relative humidity
at 63°F, 50% at 84°F, and 30 % at 100°F, since the holding capacity
of the air increases with temperature while the amount of water
vapor remains the same. Another measure of humidity sometimes
used is the dew point, the temperature at which air, on being cooled,
becomes saturated and moisture begins to be deposited from it. Dew
point is closely related to vapor pressure and to absolute humidity.
The various combinations of dry-bulb temperature and relative
humidity just cited as having the same vapor pressure (15 mm Hg)
also have the same dew point (63°F).
A generalized equation for heat loss by evaporation from the
skin to air is:
fT IP P 'i
He = e v s :-^-w (2)
ru ~h re
where:
He == the rate of heat loss per unit area of exposed surface.
Ke = a constant whose value depends upon the units used.
Ps = the saturation vapor pressure at skin temperature.
Pa = the vapor pressure of the ambient air.
rn _ the resistivity of the ambient air to the outward passage of
water vapor.
Henschel 97
-------
rc = the resistivity of the clothing to the outward passage of
water vapor,
w = the proportional wetness of the skin.
To this loss must be added that from the respiratory tract.
HEAT EXCHANGE BY RADIATION
Heat will be exchanged by radiation between the surface of the
body and all of the surfaces in its surroundings which are at temper-
atures different from its own. (The term "surface" is easily under-
stood for solid objects, but for such things as the sky it must be
regarded as that hypothetical surface that would exhibit the same
radiative behavior as the sky is observed to exhibit). The details of
radiative exchange can become very complex, but, the following
simplified explanation will illustrate the principles involved.
The intensity of the energy emitted from a surface by radiation
increases as the fourth power of its absolute temperature. The in-
tensity is usually diminished below the theoretical maximum, how-
ever, by the physical nature of the surface, the relative effect being
known as its emissivity. The wavelengths of the emitted radiation
are usually distributed over a range, with a model length that de-
creases as temperature increases.
Radiation incident upon a surface is absorbed by it in proportion
to its emissivity for the wavelength involved. The absorptivity for a
particular wavelength is the same as the emissivity for that wave-
length. From an opaque surface, the incident radiation that is not
absorbed must be reflected, so that its reflectivity is the converse of
its absorptivity and thus of its emissivity—for the particular wave-
length involved.
A substance whose surface emits at maximum intensity for its
temperature is termed a "black body." (This is an unfortunate term,
since it inevitably suggests a visual observation which relates to
reflectivity rather than to emissivity, and then only in the portion of
the spectrum to which the eye is sensitive). In general, most con-
ventional surfaces other than highly polished metals are classified
as "black bodies" in the long infrared, but many of them are obvi-
ously far from black bodies in the visible range. Thus, the apparently
paradoxical statement can be made that a white shirt may be a black
body (in the long infrared).
The surface of the human body and its clothing emit only in the
long infrared range, and in this range virtually all such surfaces act
as black bodies. Emission from surrounding surfaces, however, is far
more complex. Many conventional surfaces at normal temperatures
are emitting long infrared radiation as essentially black bodies; but
some, at the same temperature, may be emitting less intensely (for
example, polished metal surfaces). Some surfaces at higher tem-
peratures may be emitting short infrared radiation, and others at still
98 HUMAN BIOMETEOROLOGY
-------
higher temperatures, visible or even ultraviolet radiation. The ex-
change between the body and surrounding infrared emitters is fairly
simple, being complicated only by the geometrical relationships of
the opposing surfaces, which often can be approximated by a single
sphere at a uniform temperature. For such a situation the appropriate
equation for radiant energy exchange is:
Hr = Kr(T* — Tj) (3)
where:
Hr = the rate of exchange per unit area of exposed surface.
Kr = a constant whose value depends upon the units used.
Tw = the absolute temperature of the surrounding sphere.
Ts = the absolute temperature of the skin.
NET HEAT EXCHANGE
The net heat exchange between man and his ambient environ-
ment can be expressed by:
H = M ± C ± R! + Rs — E (4)
where:
H = net heat gain or loss by the body.
M = metabolic heat production.
C = heat exchange by conduction-convection.
R! = heat exchange by long-wave radiation.
Rs = solar heat gain.
E = heat loss by evaporation.
If the body temperature is to be maintained at an acceptable
normal level, then H must equal zero. Small fluctuations in total
body heat are, of course, permissible. They normally occur as a
result of rapid changes in metabolic heat production or in the rate
of heat exchange with the ambient environment. Metabolic heat
production may increase by a factor of 10 within seconds as one goes
from a state of rest to maximum physical effort (from 75 to 750
KgCal per hour, or 300 to 3,000 Btu). Metabolic heat production can
be calculated since about 5 KgCal is liberated for each liter of oxygen
used by the body cells.
The heat exchanged by convection-conduction can be calculated
from equation 1. The insulation value of the air-clothing system will
vary with the rate of air movement. These relationships at 95°F are
presented in Figure 1.
Evaporative heat loss from the clothed man, as indicated in
equation 2 can be a rather complex phenomenon; however, evapora-
tion of sweat from the skin surface is a very effective means of losing
body heat. Each liter of sweat requires 580 KgCal to evaporate it.
These simplified relationships at 95°F are presented in Figure 2.
Henschel 89
-------
700
600 —
500 _
400 —
300 —
X
o
X
1
200 —
-100
80
90
100
110
120 130
140
AIR TEMPERATURE (ta),°F
Figure 1 — Heat exchange by convection between man (skin temperature 95°F) and sur-
rounding air.
To calculate radiant exchange from equation 3 requires more
complex mathematical manipulation than may appear from the form
of the equation. This is due primarily to the complexity of shapes
of most surrounding objects. If the surrounding is assumed to be a
sphere, the mean temperature of which can be measured, the rate
of heat exchange with the nude individual with a skin temperature
of 95 °F can be obtained readily from a graphic representation of the
relationships as shown in Figure 3.
Equation 4 (H = M±C±R1-[-Rs — E) can be solved using
Figures 1, 2, and 3 provided the data on metabolic rate, air tempera-
ture, radiant temperature, vapor pressure, and air movement are
available. These data can be obtained at the worksite in an industrial
environment, in a field situation, and in a controlled laboratory setup.
In Figures 1, 2, and 3 certain basic assumptions were made in order
to simplify the presentation. Interindividual differences in sweating,
(vapor pressure, at skin temperature), blood flow to the skin, muscular
100
HUMAN BIOMETEOROLOGY
-------
efficiency, body volume-surface ratio, and other factors make it
hazardous to apply data derived from these figures to specific situa-
tions.
10 20 30
VAPOR PRESS. GRADIENT,
(P ,, —P , ), mm Hg
skin air
Figure 2 — Maximum evaporative capacity as related to air velocity and vapor pressure
gradient.
RESPONSES TO HEAT
Since radiant energy exchange, air temperature, humidity, and
air movement all affect, in quantitative fashion, the same physical
process, heat balance of the body, their operations are largely inter-
changeable. An alteration in one can be duplicated or compensated
by an appropriate change in another. The effect of a rise in radiant
heat gain can be duplicated by that of a rise in air temperature; a
rise in humidity may be offset by an increase in air movement; and
so on.
At temperatures below 70°F sweating is not called into play,
Henschel
101
-------
the skin is comparatively dry, and changes in humidity are of little
consequence. As long as air temperature is lower than skin tempera-
ture, all movement will facilitate heat loss by both conduction and
evaporation, but when air temperature exceeds skin temperature a
mixed situation is created. Air movement will still increase heat loss
by evaporation, but it will now also increase heat gain by conduc-
tion-convection. The higher the air temperature, the more important
the latter will become, until it may actually override the increase in
evaporating cooling. For each set of conditions in which air tempera-
ture exceeds skin temperature, there will be an optimal air movement.
Lower rates of air movement result in sweat accumulation; higher
rates, in additional heating and a bigger burden on compensatory
sweating.
The burden placed upon the body to step up heat loss in the
face of an environmental heat load is represented primarily by the
physiological reactions designed to promote heat loss, but these re-
actions in turn may provoke other changes that add to the total
physiological disturbance. The ultimate consequences of this chain
of reactions are illustrated in Figure 4.
900
800
^ 700
.c
8 600
500
400
300
200
100
—100
1 \ I
t min. = 95°F
I
80 100 120 140 160 180 200 220 240
MEAN RADIANT TEMPERATURE (t ), °F
w
Figure 3 — Heat exchange by long-wave radiation.
102
HUMAN BIOMETEOROLOGY
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Greater Heat Loss
(or less gain) by
RADIATION & CONVECTION
When Heat Loss by Radiation
and Convection are Less Than
Heat Production of METABOLISM
Increased Heat Flow
From Body Core With
Rise in Skin Temperature
Skin Temperature Rises
(Nervous Receptors for
Warmth are Activated)
Figure 4 — Physiological reactions related to heat loss.
INCREASED FLOW OF BLOOD
When the heat loss by radiation and convection becomes less
than the metabolic heat production, the first corrective action initiated
by the body is a vasodilatation of the blood vessels near the surface
of the skin, which results in an increased flow of blood to the area
and an increase in skin temperature. There is an increase in both
convective and radiative heat loss from the body when the ambient
air temperature and the average radiant temperature of the sur-
roundings are less than skin temperature; if these are higher than
the skin temperature, the heat gain through these channels is de-
creased.
SWEATING
Sweating, the second defense mechanism, is brought into action
when there is an insufficient flow of blood to the skin to meet the
Henschel
103
-------
requirements for heat loss. This occurs usually when there is any-
thing more than a minor thermal imbalance. The number of sweat
glands activated and the rate of secretion of sweat are graded to
meet the magnitude of the imbalance. Sweat production of more
than 2 liters an hour has been observed, but a continuous sweat rate
of about 1 liter an hour over several hours each day is considered to
be the maximum production rate. This means that, except for short
periods of time, about 600 KgCal per hour is the maximum amount
of heat that will be lost from the body surface by sweat evaporation.
Sweat that is not evaporated has no value for heat loss.
Sweat production results in a drain on the water and salt in the
body. The water is usually replaced by an increase in water intake
because the thirst mechanism is sufficient to keep the water intake
and water loss in balance. Where heat stress causes large sweat pro-
duction (6 to 12 liters a day), enough fluids are not voluntarily con-
sumed to replace the water lost. This "voluntary" dehydration may
amount to 2 to 3 liters or more during an 8-hour working day. The
"voluntary" water deficit is usually replaced during meals and non-
working hours if an adequate supply of drinking water is available.
Dehydration in excess of 3 liters may have serious physiological and
clinical consequences.
HEAT-INDUCED ILLNESS
If the normal responses of increased skin-blood flow and sweat
production are not adequate to meet the needs for body heat loss or
if the mechanisms fail to function properly, physiological breakdown
may occur. There are four major categories of heat-induced illnesses:
heat exhaustion, dehydration, heat cramps, and heat stroke.
HEAT EXHAUSTION
This is a state of collapse caused by an insufficient blood supply
to the cerebral cortex as a result of dilatation of blood vessels in
response to heat. The failure here is not one of heat regulation, but
an inability to meet the price of heat regulation. A critical low ar-
terial blood pressure results partly from inadequate output of blood
by the heart and partly from the widespread vasodilation. Inadequate
cardiac output results, in turn, from a fall in the volume/capacity
ratio below unity. The chief factors that may bring about this state
of affairs are:
1. Increasing vascular dilatation and decreasing the capacity of
the circulation to meet the demands for heat loss to the en-
vironment, exercise, and digestive activities.
2. Decreasing blood volume by dehydration, gravitational edema,
adrenal insufficiency, or lack of salt.
3. Reducing cardiac efficiency by emotion, malnutrition, lack of
physical training, infection or intoxication, cardiac failure.
104 HUMAN BIOMETEOROLOGY
-------
DEHYDRATION
In its early stages, dehydration acts mainly by reducing the
blood volume and promoting heat exhaustion. But in extreme cases
it brings about disturbances of cell function, which increase and re-
inforce each other with worsening deterioration of the organism.
Muscular inefficiency, reduced secretion (especially of the salivary
glands), loss of appetite, difficulty in swallowing, acid accumulation
in the tissues, and nervous irritability followed by depression in-
tensify; uremia, fever and death terminate the picture. A surprising
feature is the persistence of urine excretion in small amounts (5 cc
per hour) in the face of dehydration. Clinical experience suggests
careful administration of water to drink, the primary treatment.
The addition of chloride, glucose, and perhaps alkalies is recom-
mended.
HEAT CRAMPS
A condition of cramp-like spasms in the voluntary muscles is
caused by a reduction of the concentration of sodium chloride in the
blood below a certain critical level. Just why cramps should follow
a fall in blood chloride is not clear, but the association is certain and
the relief obtained by the administration of chloride may be spec-
tacular. A high chloride loss is facilitated by high sweating rates,
lack of acclimatization, and depletion of chloride reserves by low
dietary intakes of salt and adrenal cortical insufficiency. A high water
intake makes dilution of the remaining chloride easier. The actual
critical level of blood chloride concentration varies and is affected by
factors such as general health in a manner not yet understood.
The abdominal as well as the limb musculature may be affected,
the site not necessarily being related to the preceding exercise.
Whereas abdominal cramps may simulate acute surgical conditions,
limb cramps resemble exercise or nocturnal cramps. Their persistence
without saline therapy and their abolition by it provide the clue.
Heat cramps can be prevented by taking extra salt whenever heavy
work is to be carried out in hot dry environments, especially by
unacclimatized persons.
HEAT STROKE (HYPERPYREXIA)
Heat stroke occurs when the mean temperature of the body is
such that the continued functioning of some vital tissue is endangered
thereby. It represents, of course, a marked failure of the heat regu-
lating mechanism to maintain a proper balance between the two
sides of the heat balance. The chief factors which may bring this
about may be classified as follows:
1. Reduced heat loss—lack of sweat glands, inhibition of sweat-
ing, inadequate peripheral circulation, high environmental
temperature, high humidity with restricted convection.
2. Increased heat reception—radiant energy absorption, environ-
mental temperatures above skin temperature.
Henschel 105
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3. Increased heat production—muscular exercise, pyogenic
agents, overactivity of the thyro-adrenal apparatus, rising
body temperature, agitation.
4. Damaged heat regulating center—brain injuries or infections.
The critical body temperature for man lies between 108 and
112°F, depending upon the length of time that the tissues are so
exposed. The cause of tissue damage and finally death is probably
a mixture of protein denaturation, enzyme degradation, alteration in
the physical structure of the cell membranes, and changes in the
viscosity of the cellular protoplasm. It is unlikely that this crisis will
be reached in a healthy, acclimatized man carrying out normal activi-
ties in a normal climate. But under severe emotional and physical
stress and very hot conditions, heat production may reach a level
high enough to produce heat stroke without prior onset of the usual
escape provided to man, that is, heat exhaustion.
Relief is secured only by an early and effective reduction of body
temperature—usually obtainable by wrapping the patient in wet
sheets and playing a fan on him. Sometimes it is necessary to resort
to packing in ice. A resistance to gentler cooling methods is very
likely to occur in cases where the hyperpyrexia is partially caused by
infection. In such cases the effect of the infection is to set the heat
regulating "thermostat" at an abnormally high level, so that gentle
cooling results only in vasoconstriction, with negation of the cooling
effects. When drastic cooling is used, however, care has to be taken
that the temperature is not lowered too fast or too far.
ACCLIMATIZATION TO HEAT
The fact of acclimatization is well attested by both experience
and scientific observations, and some of its features are known; but
as yet much of the basic mechanisms are still elusive. With the onset
of a heat wave or when one is suddenly transported to a hot environ-
ment, it is common experience to observe impairment in performance
capacity and strong heat discomfort and distress. Tasks easily per-
formed in a cool environment become difficult, and heat discomfort
interferes with rest and eating. If, however, the exposure to the
heat is continued for several days, performance gradually returns
to normal, heat discomfort subsides, at least to some extent, and
acclimatization to heat occurs. The improvement in performance
and sense of well-being is more than accustomization; it is the result
of certain well defined and other more obscure, physiological adapta-
tions.
Acclimatization to heat results, at least in part, from increased
protection against hyperthermia since some of the initial distress of
heat exposure results from the hyperthermia. There are other adapta-
tions, e.g., improved cardiovascular function. The acclimatized indi-
vidual is able to work in the heat with a lower body temperature, a
lower heart rate, and a more stable blood pressure than before
106 HUMAN BIOMETEOROLOGY
-------
acclimatization. Some increase in sweat production also may occur.
Other alterations implicated, but not fully proved, include changes
in adrenocortical activity, blood volume, and venomotor tone. Re-
gardless of which changes are most important, the improvement in
performance with heat acclimatization is referable to the increased
ability to maintain adequate cardiovascular function despite a high
heat load.
The fully heat-acclimatized individual, then, shows no important
decrease in ability to do physical work in the heat as compared to the
amount he can do in comfortable conditions. This does not mean,
however, that he is insensitive to the heat. There may be some psy-
chological effects even in the heat-acclimatized individual:
(1) Some loss of mental initiative.
(2) Decrease in accuracy, particularly in poorly motivated indi-
viduals.
(3) Need for greater concentration to do a given task.
(4) Possible personality change.
SUSCEPTIBILITY TO DISEASE
Early studies of mortality during hot weather in a large Amer-
ican city have been supplemented recently by an analysis of records
over 9% years, with the following conclusions:
1. Tolerance to climatic change decreases with increasing age
past 25.
2. Mortality increases notably in hot summer months.
3. The mortality is at a minimum in normally hot summer
months, but high peaks are superimposed by hot spells.
4. Rapid fluctuations in temperature during summer months are
accompanied by a significant increase in mortality.
5. In the total period the highest single daily mortality occurred
in an exceptionally hot period.
6. Temperature is the most significant environmental factor in
summer mortality.
CONCLUSION
These data and previously familiar evidence place the respon-
sibility for increased mortality firmly on temperature fluctuations
and exceptionally hot periods, but absolve continued "normal" heat.
It would seem that attempts to control atmospheric conditions should
be directed at the rather exceptional peak conditions, and that exten-
sion of such controls to lower degrees of heat might not be only
unnecessary, but even undesirable, in that it would impose rapid
fluctuations upon those who have to alternate between conditioned
and natural environments.
Henschel 107
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EFFECTS OF ULTRAVIOLET LIGHT ON MAN
Dr. Harold F. Blum
Physiologist, National Cancer Institute
and Visiting Professor, Princeton University
Department of Health, Education and Welfare
U. S. Public Health Service
P.O. Box 704
Princeton, New Jersey 08540
SUMMARY
Ultraviolet light produces a variety of changes in the skin, the
relationships between which are obscure. These include the erythema
and tanning of sunburn, the production of vitamin D, and the induc-
tion of skin cancer. More than one photochemical reaction is con-
cerned, but the site of these must be in the epidermis. The injurious
effects of ultraviolet light probably outweigh any beneficial ones.
SUNBURN
Everyone is familiar with the phenomenon of sunburn, a com-
plex response to ultraviolet light that may range from a just-percept-
ible reddening of the skin to the severe blistering and desquamation
that may follow very severe exposure. The charts in Figure 1 will
orient you to the range of wavelengths that provoke this response
and to other spectral relationships. The curve labelled erythema in
part B of this figure is based on determinations of the amount of
radiation of various wavelengths that will produce a just-perceptible
reddening of the skin. The reciprocal of this amount is plotted and
the resulting curve is a spectral map, or action spectrum, of sensitivity
to ultraviolet light and may be taken as an index of the photochemical
changes that underlie sunburn; it is often called the erythemal
spectrum. The long-wavelength limit for this sensitivity is about 0.32
micron, whereas the human eye normally perceives no wavelengths
shorter than about 0.4 micron. Part A of Figure 1 shows that
antirachitic action—the prevention or cure of rickets, which depends
upon the formation of vitamin D from its precursor—has about
the same long-wavelength limit as sunburn. No relationship, how-
ever, between the two photochemical reactions has been shown. In
antirachitic action, the light-absorbing molecule, or chromophore, is
the provitamin (7-dehydrocholesterol). Part C of Figure 1 shows
that the absorption spectra for protein and for nucleic acid (the prin-
cipal suspects as chromophores for erythema and the sunburn com-
plex) have about the same long-wavelength limit as the action spec-
trum for erythema. The outer horny layer of the skin, or corneum,
which is largely protein, acts as a light filter to alter the shape of the
erythemal spectrum, so no close correspondence between absorption
by the chromophore and the action can be expected; an idea of the
transmission of the corneum is given in Figure 1-B.
Blum 109
-------
0.24 0.25 0.26 Oil OjB O.29 0.30 031 OK
TRANSMISSION,
CORNEUM
c
NUCLEIC \
. PROTEIN
V
\
\
0.24 0.25 0.26 0.27 0.28 0.29 0.30 0.31 0.32
WAVELENGTH, >J
Figure 1 — Wavelengths provoking sunburn; relationships to other actions and responses.
Figure 2-A shows curves for sunlight at the surface of the earth;
one representing the maximum condition with the sun at zenith, the
other^ showing the corresponding amount of radiation with the sun
at 60°, that is, at 4 hours from the zenith. The spectrum of sunlight
ends at about 0.29 micron, and we note that the spectrum that pro-
duces erythema—wavelengths shorter than 0.32 micron (indicated
by E)—is a very small fraction of the total. Actually there is much
more of this radiation outside the earth's atmosphere, but it is largely
absorbed by the ozone in the stratosphere, which is responsible for
the short wavelength cutoff of sunlight at 0.29 micron.
The human eye is not sensitive to the wavelengths that produce
sunburn, but has a range near the maximum of sunlight—about 0.4
to 0.65 micron. The atmosphere absorbs very little in this spectral
region so these wavelengths are affected much less by angle of the
sun than are those that cause sunburn. At 4 o'clock on a summer
HO
HUMAN BIOMETEOROLOGY
-------
WAVELENGTH
Figure 2A — Spectra of sunlight at surface of the
earth: 1, with sun at zenith; 2, with sun at 60° from
zenith [4 hr.); E, limits of sunlight causing sunburn;
V, limits of vision of the human eye.
1.5
I
e
x
\
\
N
\
\
\
\
\
V
' 1
.
1
1
1
1
/
^
'!> B. SKIN
STRUCTURES
Figure 26 — Diagrammatic cross-section of skin:
c, corneum; m, living layer; p, minute blood ves-
sels; h, hair follicles; s, hair shaft; seb., sebacious
gland; sw., sweat gland.
C. PENETRATION
OF LISHT
Figure 2C — Spectral penetration of light into
skin: N, negro skin; W, white skin.
(From The Quarterly Revew of Biology 36:50. 1961. Used with permission.)
Blum
111
-------
afternoon, when the sun is shining very brightly as far as the eye
is concerned, there is very little sunburning radiation in the direct
rays of the sun, so one must realize that the eye gives no good index
of the amount of sunburning radiation. The picture is not quite so
simple as the diagram indicates. Not only the direct rays of the sun
but also the light that is scattered back from the sky must be taken
into account; the sunburning ultraviolet is scattered much more than
is the visible part of sunlight. If we measure the amount of solar
energy falling upon a flat surface at right angle to the path of the
rays, we may find that for the visible spectrum the total light scattered
back is about 15 percent of that which comes directly. But for the
sunburning ultraviolet the situation is much different, since a
greater proportion is scattered back from the sky, coming at you
from all parts of the heavens. To our eyes the sun appears a bright
flaming spot in a mildly blue sky, but if we saw the ultraviolet that
produces sunburn, the sun would appear as a somewhat brighter spot
in a flaming sky. These things are to be kept in mind when we con-
sider the risk of sunburn. Because of this scattering back from the
sky, we may, on a bright summer day, get a severe sunburn when
lying under a beach umbrella that protects us from the direct rays
but exposes us to a good portion of the sky. Again, if we had to deal
only with direct radiation, we could say with some assurance that one
is safe from sunburn before 8 o'clock in the morning or after 4 in
the afternoon, even on the brightest summer day, because so little
direct radiation reaches us at that time. The presence of sky radia-
tion may modify this to a certain extent, although as a general rule
we are relatively safe from sunburn outside the middle of the day.
VARIATION IN SUNLIGHT
The eye is likewise not a good index of the variation of sun-
burning radiation with latitude and season. We generally think of
the tropics as having much more sunlight than higher latitudes but
this depends to some extent upon what we are talking about. At the
time of the summer solstice on June 21 or 22 there is at the Arctic
Circle about 10 percent less radiation than at the equator on the same
day; and, of course, we all know of the midnight sun. But the ultra-
violet falls off more rapidly with solar angle than does visible or
total sunlight because of absorption by ozone, which also varies to
some extent with latitude and season. At our summer solstice when
the sun is many degrees north of the equator, we should have about
as much chance of sunburn, if other things were equal, at the latitude
of Geneva as at the equator. There is of course a big "if" here, which
includes the amount of scattering from the sky. Clouds also produce
an effect (thus far I have spoken as though the skies were always
clear). Very little ultraviolet shorter than 0.32 micron gets
through heavy clouds, but with a light fog scattering may be so great
that one, if careless, is likely to get a bad sunburn. It seems that
aerosols—smoke, dust and smog—are less effective in taking out this
part of the ultraviolet than is ordinarily thought. Measuring the
fraction of sunlight that produces sunburn is difficult; we have less
112 HUMAN BIOMETEOROLOGY
-------
knowledge of its distribution over the surface of the earth than we
have for the visible spectrum or for total sunlight. This is something
we ought to know more about (1, 7).
I should also mention that sunburning radiation is almost com-
pletely cut out by ordinary, old-fashioned window glass, although
under some circumstances enough gets through to give a very slight
erythema. Window glasses made to let through some of this radia-
tion are on the market today—just why I am not sure. The idea is
widespread that sunlight is "good for you" and that one should toast
himself in the sun as much as he can. As Figure 1 shows, the same
wavelengths that cause sunburn also produce vitamin D in the skin,
and this can have an effect in preventing or curing rickets. But as a
therapeutic agent sunlight is variable, and vitamin D can easily be
obtained in other forms. The treatment of tuberculosis with artificial
sources of ultraviolet light or by exposure to sunlight was quite a fad
some years ago but now has been virtually abandoned. Some derma-
tologic conditions seem to be improved with treatment by ultraviolet
light; in this matter we could use more statistics to good advantage.
REACTION OF THE EPIDERMIS
Let us now consider the action of ultraviolet light on skin in a
little more detail. Figure 2 shows at B a diagrammatic cross section
of human skin. Most superficial is the epidermis, which for our pur-
pose may be thought of as consisting of two layers: an outer corneum
of dead cells and an under-layer of living cells. Actually there is a
gradient of aliveness. The most alive cells are the deepest; most (if
not all) of the cell division that renews the epidermis takes place in
the basal cell layer. Very little of the radiation of the wavelengths
less than 0.32 micron gets through the epidermis, so it is there
that the principal photochemical changes take place. The reddening
of the skin is the overt expression of dilation and greater blood flow
in the small vessels—capillaries, arterioles, and venules—just under
the epidermis. Very little of the ultraviolet radiation gets to these
vessels; some wavelengths, virtually not at all. So it seems most
likely that the ultraviolet produces in the epidermis some substance
that diffuses down and causes these vessels to dilate; the nature of
this vasodilator substance has never been satisfactorily shown.
The ultraviolet injures a good many of the viable cells of the
epidermis. This apparently causes an increase in cell proliferation, so
that the epidermis thickens after exposure to sunlight, and along with
it the corneum. The latter is a very good absorber of the sunburning
radiation and is one of our defenses against its injurious action; its
thickening reduces our sensitivity for some time. Along with this
proliferation and thickening comes the formation of melanin pigment
by some of the epidermal cells that are specialized for its production.
This pigment is the basis of suntan. It is popularly supposed that
the tan protects us against sunburn, but this picture is not clear. The
melanin, being produced at the bottom of the epidermis, does not seem
Blum 113
-------
to be in the best place to give protection; but it moves up through
the epidermis and is finally lost by desquamation of the corneum.
If you rub yourself with a towel after you have been exposed to the
summer sun a good deal and are well tanned, you may notice that
something black rubs off. You may think you are dirty, but this
substance is likely to be small flakes of corneum containing melanin
pigment. There is much more pigment in Negro skin, and it is dis-
tributed more uniformly through the epidermis. Negroes are much
less susceptible to sunburn than are white-skinned people. Corneum
and epidermis in Negro skin usually is thicker than in white skin, but
it is also somewhat more opaque. The pigment probably plays a role
in protection. We do not know much about the absorption by melanin
at these wavelengths, however, and the melanin pigment would not
be expected to be a much better absorber than the protein of the
corneum. The effectiveness of the corneum as an absorber for this
radiation is no doubt due largely to its being a good light scatterer
on account of its flake-like character; this effectively lengthens the
path of the rays through the corneum and permits greater absorption.
The pigment may owe its effectiveness to its being finely divided and
therefore a good scattering agent.
The tanning reaction is produced by the same wavelengths that
cause erythema, but some claim that longer wavelengths are effec-
tive. There may be some confusion here. Pigment once produced in
skin tends to bleach with time, undergoing a reduction to a leuco-
form. After some weeks the pigment may seem to have almost dis-
appeared; but if the skin is then exposed to wavelengths of light from
about 0.3 to 0.4 micron, the pigment darkens. The spectral rela-
tionship is shown in Figure 3. The pigment-darkening reaction (PD),
which is much more prominent in some people than in others, occurs
only when there is adequate 02 in the skin, whereas the initial sun-
burning reaction, erythema production, and pigment production are
virtually independent of 02. This complex of factors causes some
confusion about the sunburn reaction; some of this confusion is re-
flected in the claims for sunburn-preventing lotions that permit tan-
ning without sunburning. A variety of sun-screening creams and
lotions are on the market, and no doubt all of them are effective
to a certain extent. The question is how much protection one needs;
this is determined by the amount of exposure he is going to undergo
and the sensitivity of his particular skin (2).*
SKIN CANCEK
The role of sunlight in the production of skin cancer is of special
interest. The evidence for this is of several kinds. Negroes, who are
relatively insensitive to sunburn, are also relatively immune to cancer
of the skin. Among the white population, cancers of the skin occur
most frequently on the parts that are not habitually covered with
* Certain rare diseases are caused by light of wavelengths longer than 0.32
micron, to which the above rules for protection obviously do not apply (5).
114 HUMAN BIOMETEOROLOGY
-------
clothing, a very large proportion on the face. Some evidence indicates
a north-south distribution of skin cancer; it has been claimed that
outdoor workers are more likely to get skin cancer than indoor
workers, but this claim is not yet on a sound epidemiological and sta-
tistical basis. Perhaps the most convincing evidence is that one can
induce cancers of the skin of mice or rats by repeated exposure to
ultraviolet light of the same wavelengths that cause sunburn; under
appropriate conditions 100 percent are affected. In experiments of
this kind in our laboratory at the National Cancer Institute albino
mice were subjected to carefully measured doses of radiation at
regular intervals: once a day, once a day for 5 days a week, and
once a week. After about 3 or 4 months the animals began to
develop tumors of the skin. Figure 4 shows time to appearance of
tumor plotted against percentage of mice with tumor. The higher
the dose or the shorter the interval between doses, the shorter was
the time to appearance of tumor; the four curves from four experi-
ments represent the three different dose-conditions. In Figure 5 the
same data are plotted on the basis of the logarithms of the time to
appearance of tumor; the data for the four experiments are fitted
by similar S-shaped curves representing the integrals of a normal
distribution. In Figure 6 the points from these same experiments and
quite a number more, involving a total of over 600 mice, are pushed
together to a common mean value on the abscissa; the same curve
describes the data quite accurately. In all these experiments the
dosage of ultraviolet light was continued until the tumors appeared.
The dosage was stopped early in some experiments with the result that
the tumors were delayed in appearing,, as is shown in Figure 7. I
present these data to indicate that we have something here that is
quantitatively satisfying and should be susceptible to analysis.
Such analysis permits a few definite conclusions (3). Whatever
the action of ultraviolet light that underlies the production of the
cancers, it is cumulative; and the effect is irreversible. A number of
other things might be said about mechanism; but these two points
bear particularly on the problem of skin cancer in man. Carrying
this reasoning over from the mouse to man, one may conclude that
all of us have some beginnings of cancer in skin that has been exposed
to ultraviolet light. But statistics indicate that only a very few of us
will develop observable skin cancers in our lifetimes—depending, we
may suppose, on exposure, individual susceptibility, and luck. I don't
think most of us should worry about this very much, although anyone
who has already had a cancer of the skin ought to be careful to avoid
sunlight; this does not mean shunning the light of day but only stay-
ing out of it or behind window glass during the hours of severest
exposure. Those who are habitually exposed to the sun, such as
farmers in some of our Southwestern states or Australia or other
areas of high insolation, may find it an important problem.
Although the evidence converges to indicate that sunlight is
probably an important etiologic factor in cancer of the skin, particu-
larly in white-skinned people, this is difficult to prove statistically.
We lack good epidemiological studies made in coordination with
Blum 115
-------
I
I
0.24 0.26 0.28
0.30 0.32. 0.34 0.36
WAVELENGTH, JU.
0.38 0.40 0.42
Figure 3 — Relationships of spectra. PD, pigment darkness spectrum; E, erythemal spectrum;
S, spectrum of sunlight. Ordinates are not quantitatively comparable. (From H. F. Blum,
Carcinogenes/s by Ultraviolet Light. 1959. Princeton Univ. Press. Used with permission.)
o
o r
in'
K
O
Jo
t "
Is
08
UJ o
O n
a:
UJ
100 200
DEVELOPMENT TIME
300
4OO
days
Figure 4 — Induction of skin cancers in albino mice with repeated doses of utraviolet light.
Data from four experments; development time is time from first dose to appearance of tumor.
(From H. F. Blum, Carcinogenes/j fa/ Ultraviolet Light. Princeton Univ. Press. 1959. Used
with permission.)
116
HUMAN BIOMETEOROLOGY
-------
tO t.l tt 14 14 £J
DEVELOPMENT TIME (td), log days
Figure 5 — Same data as Figure 4, plotted on semi-logarithmic coordinates. Curves are
integral of normal distribution. (From H. F. Blum, Carcinogenesis by Ultraviolet iighf.
Princeton Univ. Press. 1959. Used with permission.)
(00,_
-O.2
-OJ 0
TUMOR DEVELOPMENT TIME
O.I
log days
0.2
Figure 6 — Data from eight experiments including those described in Figures 4 and 5 (676
mice total), brought to common mean (zero log days). (From J. Nat. Cancer Inst., 11:463-495.
1950. Used with permission.)
Blum
117
-------
measurements of sunlight; both involve considerable difficulty. To
make the epidemiological studies we need to know more about types
of skin cancer. Some types, for example, probably have little rela-
tionship to sunlight; for example, the melanomas, which often appear
on parts of the body that are not exposed to sunlight.*
"8"1605o5~
DEVELOPMENT TIME (Id), days
Figure 7 — Delay in appearance of skin cancers in albino mice as result of discontinued
dosage. Curve CH-CI describes results of continuing doses until cancers appeared. For
other curves, dosage was stopped at times indicated on abscissa by respectively labelled
arrows. (From J. Nat. Cancer Inst., 11:463-495. 1950. Used with permission.)
At present the field is open, as is any field where data are not
adequate, and one can hear many conflicting statements. For exam-
ple, one idea goes back to Charles Darwin in the middle of the last
century, that the Negroes inhabit the tropics because their pigmenta-
tion protects them against sunlight, and that this is a matter of nat-
ural selection. Darwin was very cautious about this suggestion; but
others have taken it up, and it has come to be widely accepted. In
Darwin's time, and even up to 50 or 60 years ago, little was known
about the action of sunlight on skin. Today when we analyze this
particular concept we find very little to support it (4).
Until we have better statistical data, it is hard to assess the im-
portance of the ultraviolet of sunlight as a cause of cancer in man.
When we bring together all the converging evidence, we can hardly
doubt that it is a factor. We know that a very severe sunburn can
* Since this paper was presented, a small conference was held under the
auspices of the National Cancer Institute; people particularly interested
in this question, coming from different disciplines, discussed various
aspects of the problem and how better data could be obtained. Requests
for a conference report should be addressed to the author.
H8 HUMAN BIOMETEOROLOGY
-------
be a debilitating experience—even a dangerous one—and we might,
without unduly frightening the public, try to wean them a little from
the idea that lots of sunlight on the skin is good. In the meantime
the action of ultraviolet light offers many problems for study.
DISCUSSION
Question: Could you tell me a little about the effect of ultra-
violet light on eyesight, such as in chambers having considerable
numbers of sun lamps? Is a little looking at them all right and pro-
longed looking not all right?
Answer: The cornea of the eye can be sunburned. The ultra-
violet wavelengths shorter than about 0.32 micron do not penetrate
very deeply, and probably do not cause cataract as was once thought.
But sunburn of the cornea can be very annoying and temporarily
incapacitating, and I suppose repeated dosage could be dangerous.
Cancers of eye tissue have been produced in mice by repeated dosage
with ultraviolet light (6); but here the amount of radiation reaching
deeper tissue is much greater than in man because the mouse's eye
is much smaller, so it is difficult to draw any parallel. Exposure of the
eye to ultraviolet is surely something to avoid as much as possible.
Ordinary glasses will cut out the ultraviolet that causes sunburn,
but some may get in around the margins, particularly with reflection
from the walls of a room. Most plastics now in use also cut out the
sunburning wavelengths very effectively.
Question: But ordinary eyeglasses should protect you?
Answer: Yes, except for the ultraviolet light that may get in
around the margins.
Question: We are interested in evaluating the effects of air pol-
lution. I wonder if you could say anything about the bactericidal
action of ultraviolet or its ability to destroy odors in the city?
Answer: I can't say anything definite except that the long-
wavelength limits for the killing of bacteria and other microorgan-
isms is about the same as the long wavelength for sunburn (about
0.32 micron). The killing of microorganisms seems to be tied closely
to the absorption spectrum of nucleic acids, which have their long-
wavelength limits at about this wavelength.
As for odors I have no information.
Question: Is skin cancer thought to be related to some alteration
in the DNA in the cells?
Answer: In the present state of our knowledge nucleic acids
seem the most probable chromophore, but the intimate mechanism
of cancer induction is not understood. One thing that comes out of
our analysis is that there is not a sudden mutation at the cellular
level, but a gradual change, which is presumably intracellular. It
Blum 119
-------
seems most unlikely that we deal with a mutation in the usual genetic
sense, but rather with what might be thought of as accumulation of
intracellular mutations at the molecular level.
Question: Has anyone ever attempted to study the effect of ultra-
violet radiation on bacteria that have not died but whose metabolism
may have been profoundly altered?
Answer: Ultraviolet light has been a powerful tool in genetic
studies in producing mutations among microorganisms surviving after
treatment; usually a large fraction of the microorganism population is
killed off.
REFERENCES
1. Bener, P. Tages-und Jahresgang der spektralen Intensitat der ultra -
violleten Global-und Himmelstrahlung bei wolkenfreiem Himmel in
Davos. Strahlenterapie 123:306-316. 1964.
2. Blum, H. F. Sunburn, in Radiation Biology ed. A. Hollaender. Mc-
Graw-Hill, New York. Chapt. 13, 487-528. 1955.
3. Blum, H. F. Carcinogenesis by Ultraviolet Light. Princeton Univ.
Press. 1959.
4. Blum, H. F. Does the melanin pigment of human skin have adaptive
value? Quart. Rev. Biol. 36:50-63. 1961.
5. Blum, H. F. Photodynamic Action and Diseases Caused by Light. Re-
printed edition, New York, Hafner Publ. Co. 1964.
6. Lippincott, S. W. and Blum, H. F. J. Nat. Cancer Inst. 3:454. 1943.
7. Schulze, R. Zum Strahlungsklima der Erde. Arch. Meteorol. Geo-
physik. Bioklimatol. 12:185-195. 1963.
120 HUMAN BIOMETEOROLOGY
GPO 8O1—494—5
-------
HYPOXIA: HIGH ALTITUDES REVISITED *
Dr. D. Bruce Dill
Department of Anatomy and Physiology
Indiana University
Bloomington, Indiana 47405|
SUMMARY
Data on oxygen gradient, basal metabolism, pH of arterial blood,
and hemoglobin concentration obtained during the 1962 follow-up
studies to the 1935 International High Altitude Expedition are pre-
sented.
INTRODUCTION
In the summer of 1962 six of the eight surviving members of the
International High Altitude Expedition of 1935 revisited high alti-
tudes in a study of adaptation as related to age. The six are listed in
Table 1. Bryan H. C. Matthews of Cambridge and E. H. Christiansen
of Stockholm could not participate. H. T. Edwards died in 1937 and
E. S. G. Barron, in 1957. Details about the locale, the White Mountain
Research Station, and the scope of the observations have been pub-
lished (4). In this paper we shall refer to each station in terms of its
mean barometric pressure (PB):
Station Altitud6' PB'
m mm Hg
Crooked Creek 3093 535
Barcroft 3800 485
Summit 4343 455
METHODS
First to arrive to set up equipment were J. L. Newton and J. W.
Terman, graduate students, Indiana University. The six subjects then
arrived in pairs at about 10-day intervals. During their first week
these daily observations were made in the basal state and supine
position:
1. respiratory minute volume, average for 10 minutes (Tissot
gasometer),
* Presented at the Sixth Annual Conference on Research in Emphysema,
Aspen, Colorado, June 12-15, 1963.
t Present address: Laboratory of Desert Physiology, Nevada Southern
University, Boulder City, Nevada 89005.
Dill 121
-------
2. percentages of CO2 and O2 in the collected expired air (Hal-
dane apparatus),
3. blood pressure, heart rate, respiratory rate, rectal tempera-
ture, and body weight,
4. 8-minutes spirogram with the subject breathing oxygen from
the Sanborn-Benedict apparatus. (These measurements in-
cluded two or three records of expiratory reserve, tidal, in-
spiratory reserve and vital capacity volumes. The maximum
excursion was the basis for comparison.)
After these observations had been made at least once in each sta-
tion, arterial blood was obtained from the brachial artery. Before
the puncture an end-inspiratory Haldane-Priestley sample of alveolar
air was obtained; a second sample was collected during the puncture.
Less frequent observations were later made on Forbes, Hall, and Dill,
who remained 17, 23, and 35 days, respectively. The other three sub-
jects departed after 1 week. Finally some exploratory observations
were made of exercise tolerance by use of the bicycle ergometer.
Table 1. BASAL OXYGEN CONSUMPTION.
Subject
Dill
Hall
Forbes
McFarland
Keys
Talbott
At sea level,
ml 02/min
213
255
227
242
236
231
First week at altitude,
% of sea-level value
PB = 535
108
108
111
119
105
111
PB = 485 PB
121
109
112
119
106
110
= 455
121
111
107
100
122
113
Average 234 110 113 112
Subsequent weeks at PB = 485, % of sea-level value
Dill
Hall
Forbes
2nd week
109
102
100
3rd week
108
105
101
4th week 5th week
105 112
RESULTS
RESPIRATORY MINUTE VOLUME, VE
Respiratory adaptations have been described(6). The average
percentage increases expressed at BTPS (body temperature and
pressure, saturated) are given for each station:
122 HUMAN BIOMETEOROLOGY
-------
PB> Average
mm Hg ventilation increase, %
535 20
485 34
455 44
Comparable observations were not made on these men in 1935, but
Chiodi(3) has made similar observations on young men: their re-
sponses were on a par with ours.
The average observed V values, BTPS, were inversely propor-
tional to the partial pressure of oxygen in the atmosphere. Observa-
tions of Dill were continued for 5 weeks. A steady state was reached
in the second week, as shown in the following comparison, taking the
sea level value as 100:
vl
PB, mm Hg 535 485 455
1st week 114 141 143
2nd week 119 133
4th week 120 131
5th week 117
Cheyne-Stokes breathing(7), was not obvious while subjects
were awake but frequently occurred during sleep. One awakens with
an acute air hunger and breathes rapidly and deeply for a minute
or less.
BASAL OXYGEN CONSUMPTION
The many records in the literature of basal oxygen consumption
at altitude leave one undecided as to whether it differs from that at
sea level. One such study (11) reported increases from 6 to 11 percent
indoors at 3,470 m and much greater increases outdoors in the sun,
with subjects clothed and unclothed. A review of 14 studies of basal
oxygen consumption at altitude (1) revealed changes ranging from
0 to 49 percent with median values of 7.5 percent at 3,470 meters
and 8 percent at 2,900 meters. Balke reported an average increase of
only 1.4 percent; he believed that the wide range of values reported
in the literature can be explained by fluctuation in factors other than
altitude, including radiation, temperature, and the degree and in-
tensity of prior exercise. The last factor may play a major role: the
residual effects of long-lasting strenuous exercise on resting oxygen
consumption may last many hours or even days (9). In a recent
study(8), three measurements were made of Vo2 on successive days
first at Denver, 1,600 meters, and then on Mt. Evans, 4,320 meters.
Dill 123
-------
In one male and one female Vo2 decreased 5 percent. In another
female and in three males the increases ranged from 4 to 8 percent.
The ages ranged from 24 to 37 years.
Our observations appear to be the first on record on men of ages
58 to 71 at altitude. The summary of basal Vo2 values in Table 1
clearly demonstrates that an increase occurred in all subjects, averag-
ing from 10 to 13 percent in the six subjects during the first week at
altitude. Values for Dill, Hall, and Forbes remained elevated during
subsequent weeks, although less so than during the first week. Heart
rate tended to increase with the metabolic rate, but the correlation
was low; evidently in the basal state independent influences affect
heart rate and metabolic rate.
Interpretation of our findings is difficult because of the lack of
prior comparable measurements on four of us previously at high
altitudes. We do have single observations on Talbott and Dill before,
during, and after our 1929 Leadville study at 3,100 meters:
Dill
Talbott
Before
246
242
Voo, ml/min
During
230
240
After
220
265
These values are all within the normal day-to-day range; at altitude
the Voa was the same or slightly below the average at sea level. We
were moderately active in climbing at Leadville. In 1962 none of us
exercised much and during the first week very little. Hence the long-
lasting increase in basal Vo2 that follows strenuous exercise could
not have explained the increase in metabolic rate seen in all of us
in 1962. For the moment we shall describe this increase as being
associated with age for reasons unknown.
GAS EQUILIBRIA IN THE LUNGS
Observations on the composition of alveolar air and arterial blood
have been reported (14). Compared with responses of the subjects in
1935, alveolar pCO2 values were somewhat lower for a given altitude.
This seems somewhat incongruous since their respiratory minute vol-
umes averaged the same as those reported for young men(3). Except
for Hall the difference is small; it may be accounted for by individual
differences unrelated to age. There was no significant gradient of
pCO2 from blood to alveoli. On the other hand, the gradient for
oxygen averaged +3.0 mm Hg in 1935 as compared to 12.4 in 1962.
In two young men, Terman and Newton, the p02 gradient was low as
in ourselves in 1935.
By virtue of the increased alveolar ventilation and the main-
tenance of an alkaline pH (about 7.5), we were able to maintain
about the same percentage saturation of arterial blood with oxygen
124 HUMAN BIOMETEOKOLOGY
-------
as seen in young men at comparable altitudes, a topic we will now
consider.
ACID-BASE BALANCE AND PERCENT OXYHEMOGLOBIN
Studies of arterial blood included determination of pHs) CO ,
and O2 contents, of hemoglobin by the cyanmethemoglobin method,
and of CO2 and O2 contents of blood equilibrated at known pCO2
and pO2 values and at body temperature. The pO2 in the tonometer*
172 mm Hg, was adequate to saturate the hemoglobin and thus to
give the oxygen combining capacity. The pCO2 in the tonometer was
34.7. From this baseline and the known properties of blood we calcu-
lated the T40, i.e., the CO2 content of oxygenated blood at pCO2 =
40 mm Hg. The interrelations between these measurements enabled
us to check the reliability of our results. In addition, as reported
elsewhere (4), some of our measurements were compared with those
made by Severinghaus with a gratifying outcome.
The summary of our findings in Table 2 shows a moderately
uniform pattern of response. The average CO2 combining capacity
of oxygenated blood, T40, declined almost 2.4 mM in the six subjects
during the first week. It did not change significantly thereafter in
the two subjects studied. In round numbers the decrease was from
21 to 19 mM. Among the six individuals only Hall departed from
the pattern. His T40 was low at the beginning; it ranged from 19.1
at the beginning to a minimum of 17.6 at the summit a week later
and then increased to a final value of 19.0 in the third week at PB 485.
The pH of arterial serum showed an immediate response; it was
7.40 at sea level and averaged 7.49 on the first day at PB 535. It in-
creased to 7.53 at PB 485 and to 7.54 at the summit PB 455. In Hall
and Dill it remained stabilized at about this level during the re-
mainder of their stays. Dill was the only one to depart much from
the general response: his pHs was 7.41 the first day, whereas the
others ranged from 7.48 to 7.52.
Values for percentage saturation of hemoglobin were more scat-
tered than those for other properties of the blood. At PB 535 the
range was from 76 in Dill to 88 in Keys. At PB 435, Talbott was
lowest, 69, and McFarland highest, 82. In subsequent weeks at PB 485
Dill's values were 83 and 86 and Hall's 84 and 84. Finally, during a
visit to the summit in the fourth week Dill's value was 81 percent,
compared with 73 percent 3 weeks earlier.
The barometric pressure at the summit, 455, was appreciably
greater than at the Montt station in our 1935 study (5), 429 mm. This
difference must be taken into account in considering the following
averages for 10 men at Montt and for 6 of them at the summit in 1962.
Arterial HbO2, %
Arterial pHe
1935, PB = 429
78.0
7.45
1962, PB = 455
79.0
7.49
Dill 125
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Table 2. ACID-BASE BALANCE AND PERCENT OXYHEMO-
GLOBIN IN ARTERIAL BLOOD IN BASAL STATE
Subject
Dill
Hall
Forbes
McF.
Keys
Talbott
Avgs.
Dill
Hall
First week at altitude
at sea level
T40a pHE %HbQ2
21.7 7.42 93
19.1 7.38 97
21.6 7.38 92
22.5 7.40 95
20.9 7.40 99
21.5 7.43 94
21.2 7.40 95
PB = 535
T40 pHs%Hib02
20.6 7.41 76 '
18.0 7.50 94
19.1 7.50 87
20.4 7.48 84
21.1 7.51 91
21.9 7.52 82
20.2 7.49 8&
PB = 485
Ti0 P«,%Hb02
20.4 7.52 76
18.6 7.56 80
19.1 7.52 82
19.5 7.52 80
20.2 7.56 88
20.6 7.53 78
19.7 7.53 81
PB = 455
T40 pHK%Mbt32
20.9 7.53 73
17..6 7.53 87
18.2 7.57 83
18.7 7.53 82
18.2 7.54 80
19.1 7.52 69
18.8 7.54 79
Subsequent weeks at altitude
PB = 485
2nd week
18.0 7.52 84
PB = 485
3rd week
19.4 7.49 83
19.0 7.50 84
PB = 455
4th week
19.8 7.53 81
PB = 485
5th week
19.2 7.50 86
a Total CO2 of oxygenated blood at pCO2 = 40 mmHg.
HEMOGLOBIN CONCENTRATION
It is well known that one of the early responses to the stimulus
of oxygen deficiency is increase in hemoglobin concentration in the
blood. No exception has been found to this from the days of Paul
Bert to recent observations in Peru (20). Re-examination of data
from the Anglo-American expedition to Pike's Peak in 1911(7)
yielded interesting information. Haldane, aged 51, showed the slowest
rate of increase in hemoglobin concentration, and at the end of the
35 days on Pike's Peak the lowest value. Douglas, aged 29, showed
the most rapid and the greatest response. Responses of Henderson
and Schneider, aged 38 and 37, respectively, were intermediate. Our
findings, reported by Dill, Terman, and Hall, Clinical Chemistry
9:710-716(1963) in a number honoring D. D. Van Slyke, surprised us.
Five members of our party showed a decrease and the sixth, only a
small increase. In the three subjects who spent 2 weeks or more at
altitude, hemoglobin concentrations rose above the sea level values
eventually: in Dill at 23 days, in Hall at 8 days, and in Forbes at
11 days.
We have no observations on blood volume and hence can only
speculate on the nature of related responses to high altitude. One
possible interpretation of our findings is that in the early stages of
adaptation in our age range, plasma volume increases faster than
red cell volume. It does not seem likely that a high rate of red cell
destruction was involved, since we did not engage in much exercise
126
HUMAN BIOMETEOROLOGY
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during the first week. Neither is it likely that water balance was
upset, since body weight changed little from day to day. The changes
ranged from a gain of 2.5 kg by Talbott to a loss of 2.2 kg by Forbes.
The novelty of our findings points to the need for further study.
Frequent measurement of red cell and plasma volumes should be
coupled with daily observations of hemoglobin concentrations. Cardiac
output might be useful in interpreting observations on work capacity
and other criteria of acclimatization. The daily urinary content of
erythropoietin might prove significant.
BASAL HEART RATE
Comprehensive reviews(12, 2) indicate that up to a critical alti-
tude the basal heart rate eventually returns to its sea-level value.
In mountaineers this critical altitude may be as high as 6500 m(73).
The rate is higher during adaptation and the time required for attain-
ing the sea-level rate is greater as altitude increases. Results are
summarized in Table 3. Dill, McFarland, and Keys showed small
increases during the first 2 days at PB 535. All but Keys showed in-
creases during the next 3 days at PB 485; during the next 2 days at
the summit increases above sea level were less and were seen only
in four of us. In subsequent weeks values at PB 485 and 455 were
within the day-to-day range of sea-level values. Our group tended
to show small increases during the first week, but in the three who
stayed longer the sea-level value was attained.
Table 3. BASAL HEART RATES
First week at altitude, % of sea-level value
Subject At sea level PB = 535 ^^ PB _ 455
Dill
Hall
Forbes
McFarland
Keys
Talbott
65
70
61
60
58
66
106
100
98
109
104
99
114
103
107
113
96
122
112
89
108
107
100
106
Average 63 103 119 104
Subsequent weeks; % of sea-level value
2nd
Dill
Hall
Forbes
week
101
107
104
PB = 485
3rd week 4th week
102
106
89
PB = 455
5th week 3rd week
96 106
Average 104 95 102 96 106
Dill 127
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BASAL BLOOD PRESSURE
The record of basal blood pressures is presented in Table 4. Al-
though some values exceeded the expected day-to-day range, no
consistent pattern of response was apparent.
Table 4. BASAL BLOOD PRESSURES BY AUSCULTATION
Subject
At sea level
First week at altitude,
% of sea-level value
PR = 455
Dill
Hall
Forbes
McFarland
Keys
Talbott
121/78
140/76
129/88
125/88
123/74
158/114
135/78
143/109
125/75
126/84
142/86
144/88
136/80
136/90
128/80
130/79
146/87
163/98
126/74
140/96
127/71
134/82
136/65
152/93
Average 135/86
137/87
140/86
136/80
Subsequent weeks
PB = 485
PR = 455
2nd week 3rd week 4th week 5th week 3rd week
Dill
Hall
Forbes
126/78
124/84
130/85
132/80
140/85
132/80
140/78
126/80
130/84
PARTITION OF LUNG VOLUMES
Observations of the breathing pattern and partition of lung
volumes were made with the Sanborn-Benedict apparatus two or
more times at each station and once or more at sea level. The pattern
at altitude may have been altered as part of the response to the in-
creased oxygen pressure. We have no evidence as to the nature or
magnitude of such possible effects. Hence for the moment we shall
devote our attention to lung volumes. The procedure was to obtain
a 2- or 3-minute record after the subject had been in the supine posi-
tion for y2 hour or longer. He was then instructed to expire slowly
and completely and then to inspire slowly and to his limit. He re-
sumed natural breathing for 2 or 3 minutes, then the maneuver was
repeated in reverse order. The maximum excursion was taken as the
record of vital capacity. The best-fitting parallel lines were drawn
to represent the end-tidal and beginning-tidal excursions. The ver-
tical distance from the point of maximum expiration to the line of
end-tidal excursions is taken as a measure of expiratory reserve
volume. Similarly the vertical distance from the line of beginning-
tidal excursions to the point of maximum inspiration measures the
128
HUMAN BIOMETEOROLOGY
-------
inspiratory reserve volume. These distances measured in mm are
converted to ml; on our apparatus 1 mm = 20.9 ml. Volumes were
then calculated to conditions in the lung, BTPS.
The results, summarized in Table 5, showed large differences
between individuals. Dill's vital capacity was down 1/6 at PB
485 but thereafter was as high or higher than at sea level. Hall's
vital capacity was down 1/6 during the first 2 days at PB 535. It was
higher at PB 485 than at PB 535. Thereafter it was near the sea-level
value. Forbes' vital capacity was down by 3 to 10 percent at each
station. McFarland's vital capacity, if it changed at all, was higher
at altitude than at sea level. We have no sea-level measurements on
Keys, but his vital capacity was higher at the low and the upper
stations than at the intermediate station. Talbott showed the greatest
changes. His vital capacity was down 10 percent at PB 535, 20 per-
cent at PB 485, and 27 percent at PB 455.
EXERCISE
In cooperation with Bruno Balke our group measured exer-
cise tolerance on a few occasions. Since the full details have been
published (J. Appl. Physiol. 19:483-488(1964) only a summary is
given here. The test involved adding equal increments to the work
load on the bicycle ergometer minute-by-minute and measuring the
ventilation and oxygen consumption during each of the last few min-
utes as the subject was approaching his limit. After about two days
at PB 485 the maximal Vo2 was 55 percent of the sea-level value in
McFarland, 80 percent in Keys, and 56 percent in Talbott. After a
week it was 72 percent in Dill. These studies were continued on Dill.
After 20 days at altitude his performance at PB 485 was up to 78
percent, and after 35 days, 88 percent of his Indiana maximum. A
week earlier at PB 455 he reached 83 percent of his Indiana maximum.
This marked improvement was not wholly due to acclimatization to
low oxygen: an ergometer test made a few days later at Santa
Barbara, thanks to the hospitality of S. M. Horvath and staff at the
University of California, revealed an oxygen intake 5 percent larger
than during the previous year in Indiana.
DISCUSSION
A few generalizations may be made. One of the most surprising
is that none of us showed a rapid increase in hemoglobin concentra-
tion. On the contrary five of us showed a decrease; the oldest, Dill,
showed the greatest decrease—about 5 percent—and he did not ex-
ceed his sea-level value for 3 weeks. Having made this finding we
discovered that there was an inkling of this phenomenon in the report
of the Anglo-American expedition of 1911 (7). Further studies are re-
quired for an understanding of this phenomenon.
For reasons unknown, the basal oxygen consumption tended to
increase. This happens sometimes but not always in young men. In
Dill
129
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Table 5. PARTITION OF LUNG VOLUMES AT ALTITUDE
(Subject supine; volume in liters, BTPS)
I
1
H
M
O
Sea level
Subject
Dill
Hall
Forbes
McFarland
Keys
Talbott
Dill
Hall
Forbes
Exp.
res.
0.57
0.56
0.64
0.05
0.29
2nd
0.63
0.68
0.63
Tidal
0.79
0.76
0.90
0,58
0.54
week,
0.85
0,79
0.81
Insp.
res.
1.67
3.22
3.46
4.45
3.28
PB-
1.97
3.05
3.08
V.C.
3.03
4.54
5.00
5.08
4.11
485
3.45
4.52
4.52
Exp.
res.
0.69
0.14
0.47
0.37
0.48
0.17
3rd
0.36
0.47
PB = 535
. Tidal
0.85
0.70
0.95
0.69
0.78
0.76
week,
0.66
1.00
Insp.
res.
1.66
2.93
2.99
4.29
3.14
2.76
PB =
1.99
2.99
V.C.
3.20
3.81
4.41
5.33
4.40
3.69
485
3.01
4.46
Exp,
res.
0.37
0.40
0.73
0.27
0.57
0.17
4th
0.65
PB = 485
. Tidal
0.74
0.81
0.85
0.74
0.98
0.78
week,
0.82
Insp.
res.
1.43
2.85
3.27
3.99
2.55
2.27
PB =
1.66
V.C.
2.54
4.06
4,87
5.00
4.10
3.22
455
3.13
Exp
res.
0.72
0.40
0.69
0.53
0.20
5th
0.52
PB = 455
. Tidal
0.68
0.93
0.81
0.85
0.81
week,
0.77
Insp.
res.
1.74
3.09
3.26
2.97
1.97
PB =
1.87
V.C.
3.14
4.42
4.76
4.35
2.98
485
3.16
-------
ycnmg men it may be explained in various ways, including the long-
cotttiflaued after-effects of strenuous exercise. Nothing unusual was
noted in the responses of the heart rate or blood pressure.
The gradient of pCO2. from arterial blood to alveolar air was
normal, trait the gradient of p
-------
were both subjects and investigators; they lengthened their stay on
this account. Ancel Keys, R. A. McFarland, and J. H. Talbott each
took a week out of busy lives to participate. All tolerated the dis-
comfort and even the ordeal of arterial punctures with scarcely a
murmur. Our exercise studies were carried out with Bruno Balke
and will be reported jointly with him. Finally, the summer's work
was brought to a successful conclusion by Sid Robinson, then head of
the Department of Anatomy and Physiology, Indiana University.
REFERENCES
1. Balke, B. Energiebedarf im Hochgebirge. Klin. Wochschr. 23:223-
226. 1944. Additional details were contained in a thesis submitted to
the Univ. of Leipsig. These details have been supplied by Balke since
the thesis is not available.
2. Brendel, W. Anpassung von Atmung, Hamoglobin, Korpertemperatur
und Kreislauf bei langfristigem Aufenthalt in grossen Hohen (Hima-
laya) Arch, ges, Physiol. (Pfluegers) 263:227-252. 1956.
3. Chiodi, H. Respiratory adaptations to chronic high altitude hypoxia.
J. Appl. Physiol. 10:81-87. 1957.
4. Dill, D. B. Reunion at high altitude. Physiologist 6:40-43. 1963.
5. Dill, D. B., Christensen, E. H. and Edwards, H. T. Gas equilibria in the
lungs at high altitudes. Am. J. Physiol. 115:530-538. 1936.
6. Dill, D. B., Forbes, W. H., Newton, J. L. and Terman, J. W. Respiratory
adaptations to high altitude as related to age. Chapter 5 in the volume,
Relations of Development and Aging. Chas. C. Thomas & Co., Spring-
field, 111. 1964.
7. Douglas, C. G., Haldane, J. S., Henderson, Y. and Schneider, E. C.:
Physiological observations made on Pike's Peak, Colorado, with special
reference to adaptation to low barometric pressures. Phil. Trans. Roy.
Soc. B203: 185-318. 1913.
8. Grover, R. C. Basal oxygen consumption at altitude. J. Appl. Physiol.
18:909-912. 1963.
9. Herxheimer, H.,Wissing, E. and Wolff, E. Spatwirkungen erschopfender
Muskelarbeit auf den Sauerstofrverbrauch. Z. ges. exptl. Med. 51:
916-928. 1926.
10. Hurtado, A., Merino, C. and Delgado, E. Influence of anoxemia on
the hemopoietic activity. Arch. Internal Med. 75:284-323. 1945.
11. Kestner, D. and Schadow, H. Strehlung, Atmung and Gaswechsel.
Arch. ges. Physiol. (Pfluegers) 217:492-503 . 1927.
12. Luft, U. C. Die Hohenanpassung. Arch. ges. Physiol. (Pfluegers)
44:257-314. 1941.
13. Pugh, L. G. C. E. Animals in high altitudes: Man above 5,000 meters.
Chapt. 55 in Adaption to the Environment. Am. Physiol. Soc., Wash-
ington, D. C. 1964.
14. Terman, J. W. and Newton, J. L.: Changes in arterial and alveolar gas
tensions as related to altitude and age. J. Appl. Physiol. 1963.
132 HUMAN BIOMETEOROLOGY
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INDOOR CLIMATE
Dr. Joseph Akerman
Department of Mechanical Engineering
The University of Michigan
Ann Arbor, Michigan
SUMMARY
Indoor climate is discussed in terms of associated factors: atmos-
pheric dry bulb temperature, relative humidity, air velocity, mean
radiant temperature, and air contaminants, particularly carbon di-
oxide, control (heating, air conditioning, and ventilation), optimum
climate (activity to be conducted), and effectiveness of control (op-
timum from 97 to 70 percent). Variables affecting control include
sex, age, weight, degree of acclimatization, type of activity, and
clothing. Man's interaction with his atmospheric surroundings is
defined as a zone or band, rather than a straight-line relationship.
INTRODUCTION
The purpose of this presentation is a general discussion of the
factors that we normally associate with indoor climate and of their
effects on the people who are confined within indoor spaces. My
contacts with certain researchers indicate that we are just beginning
in this area and that we may find some radically different approaches
to housing, house construction, construction materials, and the whole
matter of the structures in which people live and work and move
around. Some of the very fundamental concepts of housing are
strictly traditional—things are done because they have always been
done that way. I think that we are going to have some real break-
throughs in housing.
When we discuss indoor climate, we usually consider such things
as atmospheric dry bulb temperature, relative humidity, air velocity,
and a long-neglected element, the temperature of surrounding sur-
faces—sometimes given as the mean radiant temperature. Then there
are what we might call normal air contaminants, if we think in terms
of lecture halls, classrooms, theatres, homes, offices, and other struc-
tures that do not have industrial contaminations. Industrial struc-
tures and buildings can present a whole new field of contaminants.
I have been doing some work with the Office of Civil Defense
recently; when we talk about the civil defense shelters, we must take
into account factors that we do not normally consider—such things
as the carbon dioxide content of the air and oxygen depletion.
CONTROL
We can approach this matter of indoor climate from the stand-
point of its control by heating, air conditioning, ventilation, or some
Akerman 133
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combination of these. Or we may consider a climate that we are
simply checking to determine its acceptability and whether it will
adversely affect some operation. This approach, of course, requires
a somewhat different type of analysis. Even when an indoor climate
is controlled, certain activities or operations are involved. Specifica-
tion of the most desirable climate cannot be separated from the
nature of the activities to be conducted in the enclosed space.
INDICES OF COMFORT
Let us discuss specific indoor spaces with controlled climates.
We most frequently control the climate from the standpoint of com-
fort. The factors that affect the comfort of an individual are such
that regardless of what you do to the climate, not everybody will be
comfortable. The Heating and Ventilating Society at one time pro-
duced a comfort chart showing "percentage of people feeling com-
fortable." The maximum shown was 97 percent; this was with very
carefully controlled conditions that were varied until the maximum
number of people said they were comfortable. In a less idealized
situation about the best one can do is to get about 70 percent of any
statistically average group comfortable. Among the variables are
sex, age, weight, degree of acclimatization, type of activity, and
clothing. Since these factors vary among individuals, it is impossible
to devise any set of conditions that will make everybody comfortable.
Since all of these factors do affect comfort, it is little wonder that re-
searchers have failed to develop one single index number to specify
degree of comfort, although they have tried very hard to do so.
The list of the indices of comfort that have been proposed and
evaluated is very long. Gagge has proposed "operative temperature";
Missenard has proposed a "resultant temperature"; Vernon and
Warner have proposed a "corrected effective temperature." There is
the concept of "effective warmth." There is an "effective tempera-
ture," originated by Houghten with the Heating and Ventilating
Society laboratory in about 1923. The Heating and Ventilating Society
has since proposed a "revised effective temperature." An "equivalent
temperature" is more commonly used on the continent and especially
in England. This terminology was developed by Duffton, who pro-
posed it in 1932. He worked with a device that he called a eupatheo-
scope, and in 1936 he developed a Mark II eupatheoscope. When you
check the literature on this "equivalent temperature," you must find
out whether the reference concerns Duffton's 1932 or Duffton's 1936
instrument. Then, in a conference sponsored by the Office of Civil
Defense a physician from the Navy presented a paper indicating that
the Navy didn't approve of any of these indices; the Navy uses a
term called "effective temperature"—the same name as that used by
the Heating and Ventilating Society, but calculated in a totally
different way.
BODY ADAPTATION
My reaction to this confused situation is that each of these con-
cepts has substantial merit. But we must consider that man's inter-
134 HUMAN BIOMETEOROLOGY
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reaction with his atmospheric surroundings is not a straight-line
proposition. That is, human physiology does not have a single vari-
able by which it controls temperature, the control varying in some
sort of a straight-line relationship with any one parameter. The
human body adapts itself to its surroundings by different mechanisms
when subjected to different thermal surroundings.
Instead of trying to find a straight-line relationship, we can say
that physiological reaction to thermal surroundings goes by zones or
bands, depending upon the type of physiological adaptation that the
human body is making. I classify this adaptation into seven zones,
or types, of reaction. I do this because the physiological reaction is
different in each of these zones. When a person is normally relaxed
and the body is making no particular attempt to adapt itself to its
thermally related surroundings, there is no particular dilation or
contraction of the blood vessels and no abnormal pulse rate or any-
thing of this sort. I call this the Neutral Zone of Adaptation, which,
in general corresponds to the Comfort Zone. What happens if the
atmospheric conditions become warmer? (Not necessarily a matter of
dry-bulb temperature or wet-bulb temperature or radiation, but
perhaps a combination of several or all of these things.) If the body
senses a warmer situation, the first thing that happens is a dilation
of the peripheral blood vessels. This dilation transfers the blood
circulation closer to the skin; it changes the thermal conductivity of
the flesh, and it changes some of the modes of heat exchange within
the body. I find the human body to be a fascinating subject for engi-
neering analysis. It has some very good built-in heat exchangers.
When blood flows down to the extremities, the extremities tend to
assume a temperature close to that of the deep-tissue temperature.
The blood coming back dissipates heat through the flesh to the skin,
whence it leaves by the standard heat transfer methods of conduction,
convection, and radiation. This is in a condition that is just slightly
warmer than normal or neutral. In the next higher zone of regula-
tion we have a completely different mechanism for cooling. If this
peripheral vessel dilation cannot regulate the amount of heat dissipa-
tion from the body, then we get into a sweating regime. The tempera-
ture at which sweating starts is different for different people, and it
is also different with different levels of activity. But when sweating
starts, heat is dissipated by evaporation. Thus we cannot assume a
straight-line relationship based on temperature to indicate heat dis-
sipation when one form of heat dissipation is by radiation and con-
vection and another is by evaporation. The next zone might not
be classed as a separate zone of regulation because it is the zone
beyond regulation. If the thermally related conditions are such that
the body cannot dissipate heat at the correct rate, then you go into
a storage regime. Heat remains in the body, body temperature begins
to increase, and if this continues for an extended time you just have
to write off the individual as a dead loss. This is actually a failure
of heat regulation.
Now let us come back down to the Normal or Neutral Zone and
see what happens in the cooler situations. If the sensation devices
Akerman 135
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within the body indicate that the heat dissipation is too great and
that it should be reduced (and this is what happens when we feel
cold), the peripheral blood vessels begin to contract; the blood
circulation is still down the deep-seated arteries, but the return
circulation is back up through veins that are deeper in the flesh and
therefore further from the skin. This action changes the thermal
conductivity of the flesh. It also puts the two streams of blood closer
together dimensionally and creates a fairly effective heat exchanger,
so that the warm blood going down the arms and legs is cooled by
the blood coming back. You have a distinct drop in temperature of
the extremities—the fingers and toes—and the blood coming back
from these extremities is warmed by the blood going down. Nature
is very effectively trying to maintain the temperatures in the vital
organs of the body—the brain, the heart, the lungs, etc. This is,
again, a method of heat regulation entirely different from the others.
Now suppose that this still can't do the job. The body temperature
continues to drop, and nature wants to take corrective action. The
next step is for the body to start an involuntary action that increases
the amount of heat generation; this is the shivering regime. The body
actually does internal frictional work, which generates more heat
energy and tries to compensate for this heat loss. Finally, if all of
these regimes cannot control the situation, you again go into a nega-
tive storage situation. Body temperature starts dropping, and if it
drops too much, you again have a failure of the heat-regulation
mechanism.
The reason, then, that we have such a confused situation on
comfort indexes is that the heat-regulation mechanisms operate in
bands or zones, and no one index will give you a continuous line
through all of these zones. These zones are not rigidly fixed; the
boundaries between them vary among individuals. For example,
the point of initial sweating may vary, even with people at rest,
between 86 and 91.4 degrees. It varies even more with people under
various levels of physical activity. In addition to these variations,
research in the United States indicates that the conditions under
which people are comfortable today are somewhat different from
those shown by experimental results obtained back in the 1920's;
these, in turn, differ very substantially from those that have been
arrived at in England.
TEMPERATURE-HUMIDITY
In the zone of neutral adaptation, the comfort zone, apparently
the principal parameter affecting comfort is the dry bulb tempera-
ture. Second to this is the temperature of surrounding surfaces; that
is, the mean radiant temperature. Relative humidity seems to be
much less important than was thought at one time. This was a
defect in the original "effective temperature" of the Society of Heat-
ing and Ventilating engineers and the comfort zone that they estab-
lished originally. Their latest revision shows that the majority of
people are comfortable at a dry-bulb temperature of about 77.5°F.
HUMAN BIOMETEOROLOGY
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The line is essentially a straight line and is virtually independent of
relative humidity between values of about 20 percent on the low end
and nearly 80 percent on the high end. The maximum number of
comfort votes came at about 77.5 degrees. Now this value disagrees
with results of studies in the 1920's, in which the maximum comfort
temperature was somewhat lower—about 72°F. A very extensive
study, also in the 1920's, by the New York State Commission on Ven-
tilation for Schools placed the temperature for maximum comfort
even lower, at around 67°F.
One of the experimenters in England has interviewed over 3,000
subjects in factories. The figures aren't meaningful until you know
the conditions under which the studies were taken. This was a group
of between 3,000 and 3,200 people, probably acceptable as statistically
large enough. These were female factory workers doing light factory
work, essentially sitting at tables. The maximum-comfort response
for the group was listed at temperatures between 62 and 64°F,
dry bulb.
I started working in the heating area nearly 30 years ago, and
in the earlier days I did quite a bit of service work on heating plants.
From time immemorial the standard heating specification in the
United States has been 70°F, but in the whole time that I have been
associated with the heating business I don't think I have seen a half
dozen thermostats set at 70. I've seen them all the way from 72,
which is a fairly common setting, to 74 which is also fairly common,
and on up to 78.
The matter of humidity, as far as comfort is concerned, is even
more controversial than temperature. In one reference I can cite,
the author makes the flat statement that there is absolutely not one
iota of experimental evidence to indicate that humidity has anything
whatsoever to do with comfort. I suspect that this is a somewhat
biased position, because this gentleman is arguing for low humidities
in residences. He contends that high humidities are doing some struc-
tural damage to residences. Now maybe the effect of humidity has
been overestimated, but I could not go along with the statement that
there is not one single item of evidence to indicate its effect on com-
fort. I think that the old comfort chart of the Society of Heating and
Ventilating did overemphasize the effect of humidity. Regardless of
the effect of humidity on the sensation of warmth (you see I'm not
saying "comfort" now, I'm saying "warmth"), I think that in a range
of possibly 20 to 80 percent relative humidity there is not much
effect. An indoor climate that is too dry produces side effects that
are highly undesirable and tend to make the individual highly un-
comfortable. For example, when the relative humidity drops too
low, I immediately begin to get a dryness of nose and throat that is
extremely irritating.
MEAN RADIANT TEMPERATURE
In the United States the matter of mean radiant temperatures
was long overlooked. In the original research of the Heating and
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Ventilating Society on comfort, the subjects were tested in a test
chamber in which the walls were at the same temperature as that of
the air; the effects of mean radiant temperature were completely
masked in this study. Although this study was a monumental break-
through in the study of comfort, we must recognize that it was done
before all the factors were tied down. Baker, in England, started
working on radiant heating concepts, and one of his disciples, Adlam,
came over to the United States and carried the gospel over here. While
I am not a strong exponent of radiant heating, I think that one thing
that this movement did was to emphasize that there is such a thing
as a radiant effect that must be taken into account. The general rule
of thumb is that you can drop the air temperature in a room 1°F
for each 1°F increase in mean radiant temperature, starting at about
70°F.
There may even be some directional effects in radiation. The
mere fact that you have a high mean radiant temperature does not
assure comfort if you have a situation like that in many school
buildings, where windows contain a single glass and the student's
bodies radiate to this glass. Even a corresponding high-temperatiire-
radiating surface in some other direction may not produce comfort.
Nevertheless, all kinds of ridiculous commercial claims are made in
respect to this situation. One company manufactures a school heating
unit that throws a curtain of warm air up over the glass; some of
their salesmen claim that this blocks the radiation to the glass. If
you can block radiation with an air current, you are doing something
that I never had explained by basic physics. You can force enough
hot air up over the glass that the rate of heat transfer through the
glass climbs to such a high level that the surface temperature of the
glass increases and thereby reduces the amount of radiation. But
this seems to be to be doing it the hard way.
MODEL SETTINGS
To summarize this part of the discussion, we can say that most
commercial specifications accept 70 °F dry bulb as the correct winter
temperature. Humidity is usually specified somewhere between 30
and 40 percent for winter comfort conditions. But most thermostats
are adjusted somewhat higher. Summer conditions almost universally
are specified at 80°F dry bulb and 50 percent relative humidity.
Summer conditions are a little more complex. In the summertime
there is a question of just how much comfort you can afford in a
given air-conditioning situation. Certainly it is beneficial in certain
industrial and commercial applications to maintain a temperature
below the sweat point, even if it does not produce complete comfort.
For example, if you maintain a drafting room below the sweat
temperature, you will improve the quality of the tracings tremen-
dously.
The ideal condition also seems to depend on the period of occu-
pancy. At one time we felt that severe physical hazards are involved
138 HUMAN BIOMETEOROLOGY
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in going into a hot atmosphere from a cooled space and also in coining
to a cooled space from a hot atmosphere. Recent information indi-
cates that this does not produce much chance of physical damage,
but certainly it does produce a psychological shock. To condition a
store or commercial building for people who are coming in, staying
in a short period of time, and going out, you raise the dry-bulb tem-
perature somewhat and also produce a compensating effect by reduc-
ing the relative humidity. If you work with nature and set up a
situation in which the perspiration can evaporate quite readily and
let this do a part of the cooling job, then you can produce some fairly
comfortable conditions even at high temperatures. We are now talk-
ing about the regime in which there is enough sweating to make this
effective. If temperatures are below the sweat point, relative humid-
ity will have virtually no effect. When you complete the design, set
up the specifications, and get the equipment installed, you'll probably
find that the owner has arbitrarily set the thermostats for the comfort
of his employees because he says clerks are harder to get than
customers.
SPECIAL APPLICATIONS
I want to add a few footnotes here about some special applica-
tions. The Federal government, through the Department of Defense,
Office of Civil Defense, is dispensing information on engineering re-
quirements for fallout shelters. A fallout shelter is a space that pro-
vides a reduced incidence of radiation; it you stay in this shelter for
approximately two weeks, the radiation level outside should have
fallen enough that you have a fair chance of survival. Here you are
not designing for a plush situation in which people can relax and
enjoy themselves in complete comfort for 2 weeks. You want the
people to survive, and also to be able to do certain tasks when they
leave the shelter. We are trying to find some happy medium between
plush comfort conditions and the minimum conditions required for
survival. One of the first problems you encounter in the design of
mechanical equipment for fallout shelters is oxygen concentration.
Air normally contains about 21 percent oxygen; if the percentage
goes below about 14 percent, then you begin to encounter difficulties
with the respiration processes. Fortunately, this is one of the easier
problems in fallout shelter design. With blast shelters or with bio-
logical and chemical warfare shelters, which must sometimes be but-
toned up absolutely tight, you may run into difficulty. Also in a
submarine or any other completely closed container for human beings,
oxygen concentration may become a matter of grave concern. In the
design of fallout shelters, however, some other parameter usually is
more important than the oxygen concentration. One of these is the
carbon dioxide concentration. At present it is considered that a 3
percent concentration will impair functioning—people can't perform
minimum routine tasks properly. The thinking recently was that with
1% or 2 percent concentration, people would not be physically im-
paired. Later research has indicated that such concentrations do pro-
duce very definite physiological changes, some of which will continue
Akerman 139
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to affect a person for a week or so after he leaves the environment
if he has been exposed to it continuously. Here again, you must try
to devise experiments that are directly related to actual situations.
In the initial studies on carbon dioxide concentration the subjects
were exposed to the test concentration for 8 hours. Then they left
the test facilities, went home to go about their business—eating,
sleeping, and other activities—for 16 hours in a normal atmosphere.
Then they returned for another 8 hours under test conditions. Later,
in studies in which subjects remained in the test atmosphere for 24
hours a day continuously, the experimenters obtained different re-
sults. The general thinking now is that carbon dioxide concentrations
should be maintained not higher than 1 percent if the exposure is
continuous and prolonged. Normally, if ventilation is sufficient to
maintain a concentration of carbon dioxide below this level, then the
oxygen concentration is also controlled to a sufficient extent.
Recently it has become apparent that substantially more ven-
tilation may be required for heat removal from a fallout shelter than
is required either to maintain oxygen supply or to diminish the
carbon dioxide concentration. The body is undergoing metabolic
processes at all times, and this energy must be dissipated. If a large
number of people are concentrated in a small fallout shelter, fairly
substantial amounts of sensible heat must be dissipated. If conditions
put people in the sweating regime, or if such activities as cooking or
washing throw moisture into the air, you must also remove substan-
tial' amounts of moisture. If you do it with ventilation, the amount
of air required to reduce the moisture content of the air is often
greater than the amount necessary to reduce the dry bulb tempera-
ture, and the amount required to reduce the dry bulb temperature
may be substantially greater than that required to control the con-
centration of carbon dioxide.
CONTROL AND EFFICIENCY
To return to special applications, suppose you wish to specify an
indoor climate for a factory. Is there any real reason why we should
specify the climate that gives comfort conditions? This area has not
been explored adequately by research. Ideally, since one operates a
factory for a profit, one should try to establish a condition that yields
the greatest rate of productivity from the workers. Very little work
has been done on the correlation between indoor climates and the
maximum efficiency of workers. A tremendous amount of work has
been done on the limits within which the climatic conditions must
be held for health reasons, and on how adverse the heat conditions
can be before efficiency decreases markedly. Above certain tempera-
tures, work effectiveness can drop off very fast and very substantially.
When temperatures go over 100°F, specifically, effectiveness drops
very, very rapidly. But in the range of normally acceptable factory
conditions, I know of no research that indicates whether the tempera-
ture ought to be 60, 62, 65, 68, or 70°F for the greatest work efficiency.
140 HUMAN BIOMETEOROLOGY
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Now we consider the indoor climate of schools. It is amazing
how little statistically sound work has been done on schools. One
study was made in New York back in the 1920's, and incidentally,
some people questioned some of the statistical and test procedures
used in that study. Aside from this study no well-documented re-
search tells us whether students work more effectively and more
efficiently at a comfort condition or at some other condition. Many
spot checks are made, and all kinds of people are trying to promote
ideas. At a recent meeting, one of the presentations was based on
results obtained by a questionnaire. Teachers were asked whether
they thought the students did better in air-conditioned classrooms or
in non-air-conditioned classrooms. About 90 percent of the teachers
replied that they thought that the students did better in an air-
conditioned atmosphere. One of the representatives of an air condi-
tioning company jumped up and said, "Gentlemen, we've got it now.
Here's the message. Students learn 90 percent better in air-conditioned
classrooms." We do have a tremendous amount of misinformation like
this, but nothing that documents data on whether students derive
more educational value in an atmosphere keyed to the maximum of
comfort or whether control of the indoor climate should be based on
something else. One piece of research indicates that sometimes sub-
jects do better under a programmed fluctuation of indoor climatic
conditions.
DISCUSSION
Question: Do you know of any studies of concentrations of
carbon dioxide or any other chemical species in office buildings or
similar areas?
Answer: No. I think 1 percent carbon dioxide is considered to be
completely safe. Here again we may need longer-range studies, such
as those that changed the concept from 2 percent to 1 percent. Ac-
cording to current thinking, 1 percent is satisfactory and it's almost
impossible to button up an office building tight enough to attain this.
Natural infiltration will hold the CO2 concentration below that level.
Comment: We are very much concerned about the outside at-
mosphere and about the industrial hygiene atmosphere; but huge
numbers of our population live indoors most of the time—certainly
in the winter, and for at least 8 hours a day in the summer in metro-
politan areas—yet we apparently have no concern, not from the
heating and ventilation standpoint but from the general atmospheric
standpoint, with the atmosphere we live in. Now if this atmosphere
is identical with the outside atmosphere you can say, "Well, it doesn't
make any difference." But is it identical? And if not, how does it
vary from the outdoor atmosphere?
I could also have discussed the matter of odor control. One of
the things that concerns me is that some of the odor control devices
simply depress the nerve sensations of odor, and all the chemicals
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involved in the odor are still in the atmosphere. Is this a satisfactory
situation? The individual just doesn't know whether odors are pres-
ent. But they're still there. This area of research has been somewhat
neglected.
Question: Would you say something about the geographical
regional differences of comfort in buildings? Do you have the same
comfort conditions in an arctic climate and a southerns climate?
Answer: Two of the relevant factors here, even for one given
individual, are the type of clothing customarily worn and the state 0f
acclimatization. Dress habits vary from one section of the country
to another. Since comfort is essentially based on a regular heat dis-
sipation from the body, the matter of neutral zone and the matter of
comfort can really be brought down to the concept of the body gen-
erating a certain amount of energy, part of which goes into- work and
part of which goes into heat. The heat must be dissipated. Now,
very obviously, various weights of clothing, as an insulating effect on
the skin, will vary the rate of heat transfer from the skin. Regarding
acclimatization, it is definitely known that when you are thoroughly
acclimated to one set of situations and move to another, if the changes
are extreme, then the physiological changes are pronounced. The
quantity of blood that is in circulation varies. The body thins out
the blood and produces more blood for circulation under certain con-
ditions. These two factors, clothing and acclimatization, vary consid-
erably from one point to another, and the atmospheric conditions for
optimum comfort also vary. One rather extensive study was made
in four or five key locations in the United States on optimum condi-
tions for summer comfort. Results did not show much variation. But
as I have mentioned, the variation between comfort standards in the
United States and England is wide.
Question: What would be the role of the psychological effects
here—the perturbation of the normally expected heating or cooling
situation? In England, where central heating is much more rare
than here, don't the people normally anticipate that the best you can
have could be less than you have here? You'd expect the tempera-
ture at which they'd be satisfied to be lower, just as if you went back
in time in the United States, into the 19th century. You would find
increasingly lower temperatures that were satisfactory in terms of
comfort. And conversely, as you press more and more air condi-
tioning on the population, aren't their demands in turn going to vary
in terms of wanting cooler and cooler summer temperatures or else
being less and less satisfied? In a southern state in the summertime,
85°F was considered really nice 30 years ago. Now, with air condi-
tioning, 85° is no longer satisfactory in terms of humidity.
Answer: Psychology is a very, very real consideration. An early
investigator once undertook to referee a dispute about comfort in an
opera house. The conductor wanted one particular set of conditions,
and one of the singers wanted some different conditions. In the
language of today, the investigator concluded that people are so darn
142 HUMAN BIOMETEOROLOGY
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ornery that there is no way to reconcile these differences. And since
there is no scientific way to establish who is right, you just ignore
the people. You set the conditions according to the standards and let
the people conform.
Question: You used the term "conditioning" as a factor in com-
fort. Is there any evidence to suggest that you can condition people
to a lower temperature with comfort through exposure?
Answer: I can't cite specific research, but I am firmly convinced
that this is so. The matter of physical condition does have some effect.
When you install an air conditioning system, the most difficult space
to condition is the one that houses the high-level executives. At a
tire plant one time, the works engineer had been out with the flu.
He came back to his office much sooner than he should have. He
reported that the office was drafty and uncomfortable and totally
unacceptable. We moved in a portable temperature recorder, a port-
able humidity recorder, and I think even an anemometer. We let
them sit there for about 4 days and did absolutely nothing else. By
the end of the week he was perfectly comfortable. We had done
nothing but let the recorders record; but in the meantime he had
finished getting over the flu, which he should have done at home, and
was perfectly comfortable. So I'm quite sure that physical condition
has a marked bearing on some of these things.
Comment: Regarding this situation in England, I think dress
habits have a great deal to do with it. A friend of mine just returned
from 6 months at the Rothamstead Experiment Station in England.
The laboratory there was kept at 59 degrees. They really piled on
the sweaters and jackets.
Question: I want to ask a question in regard to adaptability,
whether it is a matter of physiology. In the case of sex—women
versus men—is it a matter mainly of adaptability in that women ap-
parently are able to adapt themselves to cold weather with lighter
clothing than men? Or is it the question of fat tissue that insulates
a little better?
Answer: I'm not enough of a specialist on the subject of females
to answer this completely, but as I have mentioned, the conduction
of heat is a primary consideration. You see the body has a forced-
circulation heat dissipation mechanism—you couldn't call it a hot
water system, it's a hot blood system—for conveying heat out of the
deep tissue and getting it to the peripheral members. From there it
must be conducted out to the skin and dissipated. As you point out,
women do have a layer of fat under the skin that definitely affects
the thermal-conduction characteristics of the flesh.
Comment: I'm a good observer of women. In Brazil while I
was there the temperature got down to 77 and this was considered
cold weather. The girls started putting on sweaters; they thought this
was actually cold.
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Question: Would you comment on air movement or ventilation
rate in relation to discomfort?
Answer: Two elements are important with respect to the air
movement rate. One, that in the standard formula for calculation of
convective heat transfer the heat-conduction coefficient varies with
velocity. Further, in the evaporation of perspiration, if the air velocity
is high enough to remove the film of high-moisture-content air that
surrounds the body, then the moisture evaporates more rapidly. Air
motion very definitely changes the heat-transfer characteristics. A
further consideration, which has not been investigated enough, is that
certain parts of the human body are more sensitive to air movement
than others. You can tolerate an air movement from the front over
your face to the back at a much higher velocity than you can tolerate
a movement from the back of the head toward the front. Some studies
have been made, too, on the effects of drafts on bald heads.
Comment: Perhaps we should make a distinction between being
accustomed to conditions and being adapted to them. One tribe of
Indians in South America lived down toward the southern extremity
of the continent and were pretty primitive. They had never devel-
oped clothing. They used only capes made of animal fur, a cape that
went around the shoulders and came down approximately to the
waist. These people would go out in fishing boats in 30 to 32 degree
weather. To protect their capes from damage, they hung them on
the shore when they went fishing. So here were people with abso-
lutely no clothing on in a climate of around 30°F. The human body
is wonderfully adaptive if you omit the consideration of comfort.
I can't conceive of those conditions being comfortable even to one
who is thoroughly accustomed to them.
Question: Did this tribe die out after a while?
Answer: The last time I heard there were still a few of them
left, but they were dying off at a very rapid rate.
Question: Did they die down after they introduced clothing?
Answer: As I recall, they proved to be very susceptible to white
men's respiratory diseases, and this led to a very high death rate.
144 HUMAN BIOMETEOROLOGY
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AIR IONS AND HUMAN HEALTH
Igho H. Kornblueh, M.D.
Medical Director
Department of Physical Medicine & Rehabilitation
University of Pennsylvania
The Graduate Hospital
Philadelphia, Pennsylvania 19146
SUMMARY
Results from 50 years of research on the effects of aeroionization
are not uniform, but norms pertaining to polarity, size, and motility
of ions have been established. For treatment purposes the natural
distribution and balance of ions, including numbers, proportions, and
polarity, are changed radically. Patients respond to both negative
and positive polarity. Although ionization is not a cure, it is effective
in treating hay fever, asthma, and burns and in general post-operative
care.
INTRODUCTION
I have to apologize for presenting a topic, the significance of
which is still a matter of controversy. Scores of reputable investi-
gators on both sides of the Atlantic have demonstrated convincingly
the broad spectrum of the biological, physiological, and clinical
effects of air ions. The very vocal opposition is by far less numerous,
but more insistent, basing its objections on flimsy tests, poor equip-
ment, inadequate technique, or the occasionally too-exuberant state-
ments found in foreign literature.
We can look back to over half a century of research on the effects
of aeroionization but must concede that the results are still not uni-
form. I come from a school carrying the proud name of a famous
Philadelphian, Benjamin Franklin, the genius who demonstrated the
existence of atmospheric electricity. This demonstration, however,
has not stimulated the curiosity of environmental scientists. In fact,
work in our field has been discouraged in various ways. Lack of sup-
port is certainly most embarrassing, since the development of suitable
ion generators and ion counters must precede the experimental and
clinical phases of research. Both require part-time cooperation of
a mixed team of electrical engineers, biologists, physicians, laboratory
experts, and medical technicians. In this stage of development, in-
vestigating the effects of air ions is not a one-man affair, and we
miss very much the advice and help of a heterogeneous group.
HISTORY
The discovery of the principle of conductivity of the air by Elster
and Geitel some 66 years ago, and the work successively by Wilson,
Kornblueh 145
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Langevin, and Pollock, gradually led to the establishment of certain
norms pertaining to polarity, size, and motility of ions. By 1903, the
Russian Sokolov had formed definite ideas about the health-pro-
moting or health-restoring value of the negative ions; shortly after-
wards, in Western Europe, Ashkinass and Caspari came independ-
ently to similar conclusions. Credit for introducing artificially gen-
erated unipolar ions in experimental work goes to Tchijevsky, who,
in his institute in Voronez shortly after the first World War, gave us
the proofs of their biotropic potential. Dessauer and his co-workers
in Germany, Edstrom in Sweden, Yaglou and his collaborators, and
Bierman in this country added much to our knowledge and under-
standing of the physiological and clinical aspects of artificial aero-
ionization.
In the early 1930's work on ionization was completely abandoned
in this country until, nearly two decades later, the late W. Wesley
Hicks of San Francisco, manufacturer of electric heaters, with the
brand name of Wesix, revived the interest in this modality. Com-
plaints about discomfort in rooms heated electrically aroused the
curiosity of Hicks and Beckett and led to construction of polonium
ion generators. In 1953 we acquired one of these units and tested it
on ourselves by sleeping under the generator for about 2 months. No
after-effects were observed. Only then did we try this method on
others. In the first year we treated 11 patients suffering from hay
fever. The results were a complete failure. The twelfth patient, an
8-year-old boy with bronchial asthma, responded to inhalation of
negatively ionized air. For the first time in years he could sleep
through the night without wheezing and without shortness of breath.
The following year, employing an improved Wesix generator, we
were able to show positive results in cases of hay fever and selected
forms of asthma. At that time we did not know much about the
physical properties of ionized air and could not explain some com-
mon phenomena. Only during the last decade was a little knowledge
accumulated.
IONS
As a physician I don't dare to present our version of the physics
of ionization before this forum, since you know much more about it
than we do. Some pertinent information has been gathered in years
of practical work, however. Uppermost on this list is the fact that
for our purposes we change radically the natural distribution and
balance of ions. We modify their numbers, their proportion, and their
polarities. Outdoors one always finds both polarities. Under no con-
ditions does only one polarity, the positive or the negative, exist alone.
With rare exceptions the positive polarity is always slightly pre-
ponderant over the negative. The negative ions discharge much
faster, recombine, and therefore disappear much faster than the
positive ions. Since ionization does not follow any political bound-
aries, we are living around the globe in an ionized atmosphere. How
vital this is biologically is still unknown. Outdoor counts were made
146 HUMAN BIOMETEOROLOGY
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in Philadelphia by Davis and Speieher and in Richland, Washington,
by Corrado. A limited number of indoor studies were conducted by
Beckett, HauseM., Norinder, Sifcsna, and others. The most revealing
findings came from Case Institute. Steigerwald, in cooperation with
Weinberger arid Lynn, reported that the polluted air in cities shows
excessive amounts of large ions, both positive and negative, at the
expense of the small ones, which are common in the fresh, clean air
in Hie country.
RADIATION
Because of increased ultraviolet and cosmic radiations, higher
levels of radioactivity, and lower relative humidity, we have even
greater concentrations of small ions of both polarities in the moun-
tains and substantially lower levels of the large Langevin variety
than in the densely populated, industrialized areas with heavy motor
traffic. We have learned that the outdoor conditions with respect to
the polluted air are similar to those indoors. As long as the windows
are open, concentrations of ions of both polarities are about the same
indoors as outdoors. As soon as the windows and doors are closed,
the number of the light, small ions of both polarities decreases, while
the level of the intermediate and Langevin types goes up. Closing
doors and windows brings the concentration of small ions in a room
to a fraction of the ion levels outdoors provided, of course, that the
soil or the building materials do not contain any radioactive sub-
stances. In some brick and stone houses the outside walls contain
enough radioactivity to account for unusually high ion levels, some-
times much higher than outdoors. But that is only an exception.
POLARITIES
Common household activities, such as smoking and cooking, lower
appreciably both polarities of light ions. After smoking, frying seems
to be the greatest offender. At the same time, while the small ions
decrease, the large, slow-moving ions of both polarites increase
rapidly, creating an environment similar to one in the heavily con-
taminated city atmosphere. This is important since, according to
Chalmers, there is an inverse relation between large-ion content and
conductivity of the air.
Reinet took daily and hourly measurements of ions over a period
of 2 years in Tartu. His metering device permitted simultaneous
determination of both polarities of the small and the large ions.
Aside from diurnal and seasonal differences he was able to show that
the large ions predominate even in Tartu, which cannot match the
traffic of an American city of its size.
I would like to stress that there are no such things as good
negative ions or bad positive ones. Many patients respond to the
negative ionization, but in some instances the positive polarity is
more effective. The reasons are still obscure.
Kornblueh 147
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AIRBORNE ALLERGIES
After this long introduction I shall limit myself to the original
theme, the influence of air ions on human health. As mentioned
before, our first attempts were directed toward control of airborne
allergies, in particular hay fever. We noticed that a large proportion
of people in acute distress showed a substantial improvement up to
complete cessation of all subjective symptoms; the improvement, how-
ever, was not lasting. lonization does not cure hay fever. After the
patient leaves the ionized room, up to 2 hours later all symptoms
reappear. Patients with bronchial asthma due to airborne allergens
respond differently. Once the bronchial spasm is relieved, the pa-
tients are comfortable for a few hours. While the wheezing frequently
persists, the patients breathe freely and without effort. In the be-
ginning of our work we were very careful. We exposed the patients
for 30 to 45 minutes to relatively low ion concentrations. This pro-
cedure was dictated not so much by the fear of possible complications
but by lack of better and more powerful equipment. With this initial
experience on hand, we went a step further and tried to determine
whether ionized air has any influence on the electroencephalographic
activity of the brain. These experiments were done at the Graduate
Hospital of the University of Pennsylvania. Silverman found that
negative ionization gave a sedating effect similar to that of some
tranquilizing drugs. We observed that persons exposed to positively
ionized air had an increased respiration rate and complained of
dryness of the throat, nasal obstruction, and occasional headaches.
We were always alert to the possible effects of ozone. Ozone was
regularly determined for a number of years but has not shown any
appreciable increase in the treatment rooms above the background
level. Dryness of the throat and nasal obstruction were the most
common complaints of the people exposed to the positive polarity.
Winsor and Beckett, working with a different type of equipment,
noted similar after-effects.
BURNS
Besides the sedating and desiccating properties, ionized air has
also a marked deodorizing effect. This suggested the use of iono-
therapy in conditions where pain, discharge of serous fluid, and mal-
odor exist, as in burns. The cooperation, openmindedness, and vision
of Minehart and his associate, David, gave us the welcome opportun-
ity to test the value of negatively ionized air on burns. The results
were most rewarding. A very high proportion of patients claimed
cessation of pain after the first 10 to 15 minutes of exposure. Secre-
tion from the denuded surfaces of severely burned areas was greatly
diminished, facilitating the formation of dry scabs. Dryness and the
early formation of scabs greatly reduced the number of infections.
To this date a few hundred burns of all degrees have been treated
successfully with this modality.
148 HUMAN BIOMETEOROLOGY
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POSTOPERATIVE CARE
The sedating and pain-relieving quality of negatively ionized air
prompted us to broaden the scope of our investigations by extending
it to postoperative cases. On Minehart's service, unselected patients
were divided into two groups. One group received negative ioniza-
tion; the other group was exposed to the same generator with the
pilot light flashing and the fan running but without the ion-producing
component. The results were quite amazing. About 50 percent of
the patients who were treated postoperatively with negative ions for
2 days, six times for 30 minutes, were comfortable without additional
narcotics, otherwise indispensable during this period. Peculiarly,
certain postoperative patients do not react as well as others. For
instance, patients having been subjected to herniorrhaphies or ap-
pendectomies responded rather well to negative aeroionization, while
those having had oophorectomies and hysterectomies were not relieved
of pain. Our experience with postoperative cases is limited to less
than 200 patients including 50 controls. We understand that an osteo-
pathic hospital in Stella, Missouri, successfully treated a few hundred
postoperative patients, who required no narcotics, or only minimal
amounts, during the early period of convalescence. The generators
used in Stella were much more efficient than our own; the patients
were exposed more frequently and for longer periods of time. In
all probability, the higher dosage accounts for the better results.
In animals there seems to be quite a difference among the various
species in response to artificially ionized air. Deleanu from the De-
partment of Hygiene of the University of Kluj in Roumania, observed
in animals many positive results with predominantly negative but
also frequently with bipolar ionization. Since clean outdoor air fea-
tures a preponderance of small ions of both polarities, we may be
tempted to employ bipolar ionization indoors not for therapeutic
purposes but only as a replacement of the lost light ions for restoration
of natural conditions.
OBSERVATIONS
The reasons for the systematic debasement of and aloofness from
aeroiono- and electro-aerosol-therapy are manifold, some quite ob-
vious. For instance, placing the patients below an ion generator
suspended overhead instead of facing it is perhaps only a technical
mistake. Exposing asthmatics in attack-free intervals to ionized air
is a regrettable misconception of basic facts. But misinterpretation
of the results of one's own study belongs into a different category.
After nearly three decades, the late C. P. Yaglou was allegedly unable
to confirm some of his previous observations. A close look at his
tables shows definitely positive results. Exposure of five infants
being treated for malnutrition to very low concentrations of light
negative ions twice daily for 2 hours for a period of 2 weeks, revealed
that "the infants seemed to be more quiet and cried less during
Kornblueh 149
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ionization periods than at other times of the day." All five had higher
body temperatures and three out of the five gained weight during the
2 weeks of exposure. During the preceding and the following weeks
no elevation of temperature was observed. Of six adult arthritic
patients tested all felt relaxed after negative ionization. Only four
of these patients were exposed to the positive polarity; all reported
unpleasant or painful sensations after the seances. It is difficult to
understand why the registered feeling of air freshness noted by some
of the normal subjects under both polarities and the respiratory irri-
tation after inhalation of positive ions, as compared with the controls,
were entirely ignored by the same author.
Aeroiono-therapy is not a universal panacea, but it is certainly
a valuable addition to our therapeutic armamentarium .and is worthy
of further exploration.
DISCUSSION
Question: I would like to ask the speaker what the mechanism
of the effect of air ions could be. If we assume it is a chemical
mechanism we could take a relatively high level of ions, such as 1000
ions per cc, convert it to its chemical equivalent, and derive some^
thing like 10~9 ppm. We know that even the most powerful or re-
active chemicals would show hardly any effect at 10-3 ppm, so it is
hard to visualize how there could be any appreciable effect from 10~9
This brings up one other point: every time you ionize air you form
a certain amount of ozone. You could easily have 10-3 ppm and not
be able to detect it without some very sensitive method, which, I
think, is probably far beyond the capacity of the equipment today.
Many of the symptoms that are attributed to ions are also symptoms
of very low concentrations of ozone. For example, increased respira-
tion rate occurs at very low ozone levels. To me the only possible
reasonable explanation would be very low ozone levels, below the
detection threshold of the equipment that has been used. I wonder
if you could shed some light on these problems.
Answer: For a number of years we have carefully watched
ozone concentrations, but could not find any appreciable increase
over the background level. Someone even took the pains to report
us to the state authorities, but the investigating engineers were com-
pletely satisfied and permitted us to continue our work with high-
voltage ion generators. For 3 or 4 years we employed exclusively
polonium and tritium generators, which have practically no ozonizing
effect. Still, our clinical results were, except for the very first year,
identical with our later findings. Krueger, Winsor, and Worden use
or used in their experiments only radioactive isotopes for ion genera-
tion. Many of those present are acquainted with Krueger's ingenious
experiments, which open entirely new vistas in the field of aero-
ionization. We are greatly indebted to him for laying the founda-
tions indispensable in clinical investigations. By the way, contrary
to reactions to ozone, the respiration rate declines under the influ-
ence of negative ions.
150 HUMAN BIOMETEOROLOGY
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At present we are unable to answer the question about the
modus agendi of artificially ionized air or electro-aerosols. There
are a number of theories, but none appears convincing. This ob-
servation could be extended also to a substantial number of popular
pharmaceutical products, whose effects are known but not the ways
of action. We realize that only a relatively small number of charged
gaseous or particulate molecules enters the respiratory tract through
the nose and the oral cavity and that some of them reach the bronchi
and the alveoli. We can practically exclude any other port of entry,
since we cover the patient with nonconductive material. One school
of thought, however, suggests that exposure of the unprotected body
to high levels of ionization produces secondary induction currents.
Tchijevsky and others exposed animals to a de-ionized atmosphere
of unusually low ion concentration and reported peculiar results. It
would be most interesting to conduct similar experiments on man
and register his physiological and psychological reactions in such an
unusual environment.
I presume that you are aware of the effects of certain synthetic
fibers that produce relatively large amounts of static electricity. The
French literature is replete with statements on the pain-relieving
properties of fabrics made from polyvinyl chloride. These fibers pro-
duce negative static electricity. A substantial proportion of rheumatics
and arthritic claim freedom from pain as long as they wear under-
garments made from these fibers. This material is known also in the
Soviet Union and recommended for similar conditions.
Question: Is the French polyvinyl material available here?
Answer: I think that a New York textile firm carries the French
PVC fabrics. For some time we have been using special gloves made
from this material for massage to learn if the negative friction elec-
tricity offers some additional benefits. At present, we cannot make
any definite statements. It is interesting that while the thermal
properties of worn underwear remain essentially the same, the static
properties are greatly inhibited or entirely annulled if the garment
is not properly washed every 48 hours.
Question: Awhile back the Meteorological Department at the
Penn State University was interested in conducting some studies on
the effect of ionization on the learning rate and perhaps the re-
tention rate. Do you have any information on this?
Answer: To the best of my knowledge these studies were either
never done or are still in a very early stage. The primary difficulty,
as I see it, is the lack of powerful and reliable equipment.
Question: You mentioned that you have no information on
measurements of natural ionization in South America. A study has
been going on for a number of years in which the radioactivity from
thorium-bearing sands is being measured. In Brazil, the World Health
Organization, I believe, is supporting this study. The question came
about because a number of areas have a large amount of thorium-
Kornblueh 151
-------
bearing sands. In fact, whole cities are built upon this substance, and
people have been living on top of this natural radiation for genera-
tions. This study is being done by the Catholic University in Rio de
Janeiro, I suppose by the Department of Nuclear Physics. It has
been going on for at least 5 years.
Answer: I have not been aware of this work in South America.
However, South American medical literature sporadically brings
papers related to the field of artificial aeroionization.
Question: In your experiments how do you measure the presence
or absence of ozone?
Answer: We have been using the method of Crabtree and Kemp
for determination of ozone. As mentioned before, our experience points
to the need for a research team and constant supervision of patients
during the treatment period.
Question: Have you published lately in this field?
Answer: Papers on the effects and the technique of aeroiono-
therapy were presented in May 1963 upon invitation of the X Health
Conference in Ferrara and in September of the same year at the
summer session of the Balneo-climatological Research Institute of the
University of Rome in Montecatini.
Question: Was the professor Yaglou that you mentioned C. P.
Yaglou?
Answer: Yes, the same man who in the early 1930's attributed
to ionization a "normalizing effect" and three decades later denied
everything, in spite of the obvious facts evident in his own data.
These data show physiological or pathological effects, depending on
the kind of polarity he used. It should be mentioned that with our
present methods of assay we find that younger persons in good
health are not responsive to ionized air. Children, older people, or
persons under stress are susceptible, however.
Question: About a year ago the Farm Journal published an
article on raising chickens in Wisconsin. I am curious about what they
hoped to accomplish by using ionized air.
Answer: A paper on this topic was presented at an agricultural
conference in Chicago in December 1962. As I understand, the in-
vestigator, an agricultural engineer, had later some difficulties with
duplication of his original findings. The first impression was that the
chickens exposed to negatively ionized air had, in comparison with
the control group, fewer respiratory infections, an allegedly common
condition in chicken coops, and that their weight was slightly higher.
Somewhat similar observations on animals and chickens were re-
ported by Tchijevsky, who claimed that the animals grew faster and
reached their sexual maturity earlier under negative ionization. In
this country, Worden of the Bonaventure University, has shown on
golden hamsters that healing of surgical incisions and regeneration
HUMAN BIOMETEOROLOGY
GPO BO I -494-6
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of severed femoral nerve were enhanced by a negative ion environ-
ment and unaltered by the positive. Worden noted in mammalian
cell cultures a diminshed cell proliferation under the positive polarity
but practically no change under the negative. We are unable to
explain why a cell culture behaves differently from cells in situ in a
living animal.
Question: You mentioned previously the difference in response
to both polarities. In some cases there was a positive response to
negative ionization and in some cases there was a positive response
to positive ionization. Has anyone attempted to correlate these re-
sponses with different blood types or some other physiological
phenomena?
Answer: As far as I know no attempts were ever made in this
country to correlate the effects of unipolar ionization with racial,
constitutional, or physiological characteristics of man. Healthy young
persons are, in the opinion of many investigators, not suitable sub-
jects for research in this field. In cooperation with Griffin we have
exposed students for 30 to 60 minutes to negative ionization. No
changes of blood pressure or pulse rate were noted. With few excep-
tions, the subjective reactions of these students were negligible. The
response of a high percentage of patients in acute distress is quite
different. The effect of the negative polarity on persons of different
races or national origin was essentially alike. Our subjects were
American whites and colored, European whites, and North-African
Arabs and Berbers. The experience of foreign investigators seems to
be similar. Our somewhat nebulous knowledge of the optimal dosage
and polarity induced Malysheva-Kraskevich to make the following
statements: "It is conceivable that identically charged ions may
produce a different effect on the organism if administered in different
concentrations and under different experimental conditions. It it,
possible too that the effect of identical dq^e,s 'will vary in relation to
the length of exposure, and that heavy doses administered in a few
sessions may act differently from small doses extended over a longer
period. On the other hand, it may be assumed that in certain com-
binations of the fundamental factor (ionization) with definite experi-
mental conditions (constitutional characteristics of the patient, his
behavior, etc.) oppositely charged ions will not necessarily produce a
reverse biological effect."
Judging from the number of participants in three congresses on
aeroionization in the Soviet Union, we can rightfully assume that the
interest in this field is especially keen there.
Question: Do I understand that the treatment of burns is effected
by means of inhalation of ionized air?
Answer: In treatment of hospitalized burns, Minehart uses the
open air method. The burned areas are not bandaged. The patient
rests between two sterile sheets and remains covered except for the
face during the periods of treatment. On very warm days some
patients pull the covers partly off, but that is an exception and not
Kornblueh 153
-------
the usual routine. In our series of treatments no attempt was made
to eliminate other therapeutic modalities as intravenous fluids, anti-
biotics, or vitamins. Ion-therapy is used in burns only as an adjuvant
to other established methods. Without any doubt, the results are
greatly superior.
Question: Very often you hear the comment that people feel
good under certain meteorological conditions, like before a storm or
some weather fronts. I wonder if any measurements have been made
under these conditions.
Answer: Continuous metering of natural outdoor ionization levels
was undertaken in Boston by Yaglou; in Haifa, Israel, by Robinson
and Dirnfeld; in Philadelphia by Davis and Speicher; and in Richland,
Washington, by Corrado. The last two studies were published in the
Proceedings of the International Conference on Ionization of the Air.
Too many other meteorological factors are involved to permit evalua-
tion of the biotropic effect of a single natural element. Only under
laboratory conditions are such experiments possible.
Question: Are you familiar with the ultraviolet treatment of
blood as a means of curing hepatitis? Is there any correlation between
this and the negative ions?
Answers: I am only vaguely familiar with this method, but I
don't believe that there is any correlation with aeroionization.
Question: Do artificially generated ions sterilize the air or pre-
cipitate the aerosols? Could this possibly explain the beneficial effects
on humans?
Answer: Ions don't have a significant bactericidal or bacterio-
static effect but do precipitate the aerosols and have a marked
deodorizing force. The walls and the ceilings in the sick rooms are
getting very dirty already after a few months of intermittent employ-
ment of ion generators.
Question: In the recent Russian literature a paper describes the
ionization of air in a chamber that destroyed microbiological aerosols.
Ions were generated by a water jet; papers in the American litera-
ture discuss alterations in humidity having a bactericidal effect on
suspended organisms. I think possibly some confusion has arisen.
The Russian investigator is perhaps getting a humidity effect and
not an ion effect.
Answer: We have great difficulties with the Russian literature,
since we cannot afford complete translations. I am not acquainted
with their method of sterilization of pathogenic aerosols. In this
country, Krueger did some related work.
Therapeutic employment of charged water aerosols, known in
Western Europe under the name of electro-aerosols, was introduced
in Wiesbaden, Germany, a known spa, where a hypotonic natural
mineral water, was used for inhalation therapy in respiratory ail-
HUMAN BIOMETEOROLOGY
-------
ments. In later years, a negative electric charge was added. Such
inhalation units are being commercially manufactured in Cologne
and more recently also in Dallas, Texas. Wehner has introduced
electro-aerosol therapy (or as the Russians call it hydro-aeroiono-
therapy) in this country. He has published detailed reviews of the
available literature and his own most remarkable clinical results in
respiratory conditions. The steadily increasing numbers of upper
respiratory allergies, chronic bronchitis, asthma, and pulmonary
emphysema as sequelae of atmospheric pollution emphasize the need
for this form of adjunctive therapy proven most successful on thou-
sands of victims here and abroad.
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ECOLOGICAL PERSPECTIVE IN BIOMETEOROLOGY
Dr. David M. Gates
University of Colorado
Institute of Arctic and Alpine Research
Boulder, Colorado 80304
SUMMARY
The meteorologist's atmosphere-oriented data when used by the
biologist in solving biological problems must be reinterpreted in terms
of "life." Essentially the parameters established have meaning in
terms of flow of energy, and this flow as temperature affects the
internal physiology of the body and, in fact, determines its survival.
INTRODUCTION
I want to give you an approach to bioclimatology and bio-
meteorology that I have taken in connection with the studies of
vegetation. What I have to say about plants is equally appropriate
for animals. The techniques are the same.
The very first concern is the matter of definitions. If we say we're
going to study climate, we must also say for what purpose. Lack of
definition has persisted in ecological work for the last half century.
There are two definitions of climate, one pertaining to the atmosphere
and the other, to life. In studies of biological organisms it is rather
astonishing that the first definition has been used so consistently,
and the second has been almost totally ignored. The meteorologist,
in studying the atmosphere, has defined certain parameters that must
be registered and studied to evaluate the properties of the atmos-
phere. He has measured these parameters—he has set up networks.
The biologist, far too often, has taken over the meteorological data
for various correlations in biology, without critically questioning the
application, of the meteorological data to the biological problem, at
hand. It is not difficult to delineate this very clearly in the literature
—to show where some property, such as growth of an organism or
plant, has been correlated with mean temperature, or maximum
temperature, or the rainfall pattern.
But we must be more specific. We must ask "What do these
parameters mean?" Well, they have meaning in terms of the flow of
energy. It is actually energy that is transferred and consumed. It is
not sufficient to talk about temperatures per se, or moisture per se, or
any other parameter.
TEMPERATURE
Figure 1 shows the normal temperatures for certain animals and
groups of plants. These are normal body temperatures, with the
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maximum and minimum temperatures known for survival. This in-
formation comes from the handbook of biological data. Although not
highly accurate, the data do indicate the temperature situation in
plants and animals. For many organisms the survival regime is in
the vicinity of 40°C. This is very striking. Some plants tolerate only
up to about 40°C, and others up to 50°C. Particularly interesting are
the thermal blue-green algae, which exist at temperatures as high as
85°C. (If you put your hand in water like that you will burn it, of
course.) Lichens have been observed to survive up to 100°C.
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- THERMAL DEATH FOR MOST BACTERIA
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TEMPERATURE, °C
Figure 1 — Normal body temperatures of animals and plants and maximum and minimum
extreme temperatures for survival.
Now the question of temperature has enormous meaning. It is a
matter of an organism in an environment, the environmental char-
acteristics affecting the temperature of the organism, and then the
temperature of the organism affecting its internal physiology. The
rate chemistry is very dependent upon temperature. Many proteins
are destroyed by moderately low temperatures. Certainly many pro-
teins are destroyed in the range of 50 to 60°C; and since some plants
162 HUMAN BIOMETEOROLOGY
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tolerate much higher temperatures, we must ask the question "Are
the proteins of some plants, such as the thermophyllic algae, such
that they are not being denatured in the same way as the proteins
of other plants and animals that survive only at considerably lower
temperatures? "
REFLECTED/
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/ DIRECT /
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INFRARED THERMAL RADIATION
FROM ATMOSPHERE
\
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\ INFRARED THERMAL RADIATION
\ FROM ANIMAL
INFRARED THERMAL RADIATION
FROM GROUND
Figure 2 — Streams of energy to and from an organism in its natural environment.
RADIATION
Figure 2 is a schematic view of an organism in a normal external
environment, consisting of radiation, wind, and water. All objects at
a temperature above absolute zero radiate heat according to the
fourth power of their temperature. You get radiant heat from the
trees, rocks, and clouds. When clouds are absent, the surface of the
earth becomes much colder at night than when they are present. The
ground radiates heat thermally, and the atmosphere radiates heat.
This is particularly important, because without radiant heat from
the sky, our environment would be very much colder. Each of us
radiates heat individually, at a rate approximately equivalent to a
100-watt bulb. This heat loss must be compensated by the flow of
energy in the environment. Here in this room you are in a pure
infrared radiation environment; you're in a black-body cavity. It's
very easy to define the energetics of this environment: there is a
small amount of convective heat transfer due to the flow of air, but
since there is not much wind in the room, it is essentially a radiant-
heat thermal environment, pure and simple. If the wind blows and
it is warmer than the air, it delivers heat to the organism. If it is
cooler, it abstracts heat from the organism.
Gates
163
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SWEATING
Many organisms have the ability to sweat—to evaporate moisture
to reduce the heat stress—and save their lives through the exchange
of water. Certain animals, like the salamander, can sweat profusely.
It sweats like a wet-bulb thermometer and cannot survive a dry
atmosphere. In a dry atmosphere a salamander would lose 9 times
its body weight in 24 hours. It must live in a humid microclimate,
near streams, under rotting decayed logs, in order to survive. On
the other hand, most insects cannot lose much moisture and have
essentially no control over their body temperature and their survival
through moisture. By virtue of size, they cannot lose much moisture,
and also most insects have a very impervious, chitinous shell, which
reduces the loss of moisture to a very small value. You and I have
the ability to sweat when we need to reduce the heat load and keep
our temperatures down.
FLOW OF ENERGY
Figure 2 depicts environment as a flow of energy, and this is the
manner in which we must evaluate our environment. If we consider
meteorological parameters, such as air temperature, relative humidity,
and wind speed, we must use these properly to evaluate the flow of
energy. It is often fortuitous •when you correlate the biological be-
havior of some organism's growth, or distribution, or some similar
factor, with temperature and you get a good correlation. It is fortuitous
unless you really can show why a correlation should exist. Is there a
causal relationship? That is the question to be answered.
PLOTTING
Figure 3 shows the spectral distribution of direct sunlight and
some of the molecular reactions that occur in response to various
frequencies of radiation. The scale is frequency or wave-number
scale, which is the reciprocal of the wavelength. A wavelength scale
is shown at the top. The distribution of sunlight outside the atmos-
phere is the solid line. Notice that the spectral distribution now
peaks in the near-infrared when plotting against wave number, rather
than in the green as on all wavelength plots. The peak of solar energy
distribution is not in the green of the visible. A lot of fiction has
grown up around this idea that the sunlight peaks in the green.
We are told that this is one reason why plants are green, that the
human eye has its peak response in the green for this reason, and
other similar phenomena. This is not true. If you plot the distribu-
tion of sunlight on a wavelength scale, you do get the peak in the
green. But if you plot it on any other scale, you get the peak else-
where. When you plot it on a wavelength scale, you are plotting the
amount of energy per unit area per minute per wavelength incre-
ment. When you plot it on a frequency scale, you plot the same
energy per unit area per minute per frequency or wave-number
increment and that changes the shape of the curve. There is nothing
164 HUMAN BIOMETEOROLOGY
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sacred about per wavelength increment, anymore than there is any-
thing sacred about the wave-number increment. The important thing
is not where the peak is, but rather how much energy occurs within
certain frequency or wavelength intervals. The same frequency
interval or wavelength interval would give the same amount of
energy on any plot, but the curve has a different shape. I just wanted
to point out this feature so that you don't think always in the old
patterns. For the extraterrestrial distribution of sunlight, 50 percent
is in the infrared, about 30 percent in the ultraviolet, and only about
20 percent in the visible.
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Figure 3 — Spectral distribution of solar radiation as function of wave number. Wavelength
scale is given above curves. Energy content of each quantum of radiation is shown in ergs,
kcal, and electron volts. Reaction that may occur in plants or animals when irradiated with
each quanfum of radiation is shown at top.
SOLAR RADIATION
The solar radiation reaching the earth's surface is also shown in
Figure 3. The incident radiation is strongly absorbed by water vapor
and carbon dioxide in the infrared, strongly cut off by ozone and
Rayleigh scattering in the incident sunlight at the earth's surface as
Gates
165
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ultraviolet. The human eye will see the incident sunlight at the
earth's surface as approximately 8,600 foot-candles, and the response
is shown in Figure 3. A great deal of observations in the natural
environment have been made in foot-candles. The foot-candle is
useful if you're interested in the spectral distribution within the
sensitivity limits of the human eye, but it does not give a measure
of the ultraviolet or infrared intensity. The foot-candle measurement
has hurt us very seriously in terms of making use of a vast amount of
old data for biological studies. Above the spectral curves the energy
content of each quantum of radiation is given as a function of the
frequency. Three different scales are shown, depending on whether
you think like a physicist or like a chemist. To define it in terms of
the strength of bonds, we give it here in kilocalories, as well as in
ergs. In the visible, there is useful, bond-building, molecule-building,
photochemistry generated by radiation and plants or animals. The
chlorophyll bands are located here. In the infrared, the energy ab-
sorbed by any organism simply goes into kinetic energy of vibration,
translation, and rotation. In other words, the infrared energy absorbed
largely goes into heating an organism, and the heat helps to maintain
body temperature at a point where active physiological and bio-
chemical processes can be carried on. In the ultraviolet, the quanta
absorbed largely go into breaking bonds or breaking molecules down.
Too much ultraviolet radiation, of course, causes a destruction of
organic complexes rather than a building up. There are, therefore,
the useful photochemical region of the visible spectrum, the heat
region in the infrared, and the destructive ultraviolet.
CARBON DIOXIDE
Figure 4 shows the bands of infrared radiant heat that come from
the atmosphere toward the ground. If our atmosphere were com-
prised of only oxygen and nitrogen, as it is primarily, and had no
water vapor or carbon dioxide, the earth would be very much hotter
on the sunlit side and much colder on the dark side. Life on this
planet would not have evolved to its present form, because of ex-
tremes of heat and cold. Although these are minor constituents (CO2
is 0.03 percent by volume, and water vapor is highly variable, but
seldom as much as 2 percent), they do a great deal toward condi-
tioning and controlling the climate of the earth.
The idea that an increase in the CO2 concentration of the earth's
atmosphere has produced a warming of the earth by about 1.5°C
during the last half century does not seem to be correct. It appears
that such an effect would have required a far greater change in the
CO2 concentration than actually has occurred. A law in physics says
a good absorber is a good emitter at the same wave length. Now if
the atmosphere were black and absorbed throughout at all these wave
lengths, then it would reradiate according to the solid line shown in
Figure 4. But the atmosphere is not black; it is only semitransparent,
and it absorbs in specific bands. The atmosphere then reradiates
energy in these same bands: the radiant energy at 6 microns is due
166 HUMAN BIOMETEOROLOGY
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to water vapor, at 9.6 microns to ozone, and at 14 microns to carbon
dioxide; practically a continuum beyond 22 microns is due to water
vapor. The reason the CO2 theory of climatic change does not work
well is that the CO2 emission at 14 microns is strongly overlapped
by absorption and emission by water vapor. The overlap by water
vapor washes out any effect of radiation exchange on the planetary
temperature caused by CO2.
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Figure 4 — Thermal, infrared radiation emitted by atmosphere and blackbody radiation
from ground surface and from surfaces at 263° and 235°K.
INFRARED RADIANT HEAT
Everything on the earth's surface receives from the atmosphere
these streams of infrared radiation. If we had infrared eyes, we would
see bands of radiation of different frequencies streaming downward
from the sky at night as well as during the daytime. Without this
radiation our climate at night would be very substantially colder.
This is what gives the citrus farmer so much worry when the air
temperature cools to say 35°F and the sky is clear and dry. Then
the surface can lose much radiant heat to outer space with little
replacement, and crops may freeze severely. The infrared radiation
from the atmosphere is an important energy component for life on
Gates
167
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the surface. When the sky clouds over and becomes completely over-
cast, the clouds will radiate like the solid line shown in Figure 4.
The energy radiated by the clouds is the full area under the curve
shown. This represents considerably more energy than that from a
clear sky, which radiates only in bands.
PLANT ABSORPTION
Plants are fabulously adapted to the radiant energy environment
here on earth. Figure 5 shows how plants absorb, reflect, and transmit
radiation. Plants absorb the ultraviolet and the visible with great
efficiency. The plant pigments such as chlorophyll produce strong
absorption throughout the visible. They absorb this energy where
they need it for photochemistry. Immediately beyond the position of
the red chlorophyll band a plant becomes a brilliant reflector. It
becomes very white in the infrared. Infrared photographs of forests
and trees show up white—the trees look as though they are covered
with snow. This is shown in Figure 5 by the reflectance and the low
absorptance in the near-infrared. But this, strikingly enough, occurs
where the sunlight has a great bulk of energy located in the near-
infrared. If the plant absorbed this energy in the near-infrared with
the same efficiency with which it absorbs the visible, it would become
very substantially warmer than it does. Plants often reach tempera-
tures that take them right up to the threshold of thermal death. If
they were absorbing with very good efficiency throughout the near
infrared, they would not survive as constituted with the types of
proteins they have. Farther out in the infrared, at the longer wave-
lengths, the plant absorbs very well again. High absorptance at long
wavelengths does not matter from the standpoint of sunlight absorbed,
since sunlight has very little energy at long infrared wavelengths.
But by absorbing very well at these long wavelengths, a plant func-
tions as a good emitter, or an efficient radiator, of thermal energy. A
plant absorbs effectively where it needs the energy for photosyn-
thesis; absorbs poorly the near infrared, which it does not need; and
absorbs well at long wavelengths to function as an efficient radiator.
Reradiation accounts for about 75 percent of the energy balance on
a plant.
RADIATION MEASUREMENTS
Figure 6 shows the radiation regime in which we live. These are
actual values, measured at Hamburg, Germany, in June 1954. As
the sun comes up in the morning, the direct sunlight and the scattered
skylight produce this well-known diurnal pulse. Then the ground
may reflect sunlight, depending upon the nature of the surface. The
two together give the total solar energy received on the upper arid
lower surfaces of a horizontal leaf. A plant or animal here on the
surface receives these streams of radiation. The sum of the indi-
vidual streams of radiation determines our energy budget, not the
difference or net streams. Both the downward and the upward streams
that are incident on our bodies are effective. The meteorologist con-
siders the difference in radiation streams because he is interested in
168 HUMAN BIOMETEOROLOGY
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net fluxes, and he has a valid reason for doing this. But the biologist
often gets himself in trouble by using net fluxes, because the organ-
isms are receiving the sum, the downward plus the upward. Figure 6
shows the sums of the individual streams of radiation. A large per-
centage of biological observations in external environments have
dealt with the solar radiation components and not with thermal radi-
ation components. Yet thermal radiation contributes a very important
amount of energy to the heat budget of a plant or animal.
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Figure 5 — Spectral absorptance, reflectance, and transmittance of Populus delloides leaf.
RADIATION CLIMATE
Figure 7 shows a few radiation climates of the world as they
affect a horizontal leaf. One of the most intense radiation climates
is at the top of the Rockies and the top of the Sierras in midsummer.
The soil becomes very hot in sheltered areas out of the wind. When
the sun comes up in the early morning and strikes the high mountain
slopes, things happen fast. It is a very dramatic experience. The
desert has a strong component of this infrared radiation level. The
solar term itself may not be particularly strong, because of dust at-
tenuation and so forth, but the infrared component is certainly ele-
vated and very strong. Figure 7 gives us some idea of our radiation
climates, the bioclimates that we must evaluate to deal with man in
the open, man on the desert, man in the arctic.
Gates
169
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r(S+s) REFLECTED SUNLIGHT
RG= THERMAL RADIATION FROM GROUND
RA= THERMAL RADIATION FROM ATMOSPHERE
10 12 14 16
TIME,hr
Figure 6 — Diurnal variation of radiation components incident on upper and lower surfaces
of horizontal leaf. Total radiation incident on two surfaces is shown.
BOUNDARY LAYER PHENOMENON
Figure 8 shows the boundary layer of air near the faces of my
two young girls. This picture is a composite of two that were taken
by schlieren photography. The photographic technique shows up with
enormous sensitivity any changes in air density throughout the field
of view. Near our surfaces is a boundary layer of stationary air. This
boundary layer represents the transition from the warm skin to the
170
HUMAN BIOMETEOROLOGY
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for selected localities on earth.
Gates
171
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Figure 8 — Composite of schlieren photographs of boundary layers of air.
cooler air beyond and from the moist air near the skin to the dryer
air beyond. There is also a transition from air movement at a dis-
tance from the surface and zero air movement at the surface itself.
I experienced the boundary-layer phenomenon in a sauna in Finland.
The sauna is an extremely hot air bath. The air in the room was at
230°F, hotter than anything you ever believed it possible to experi-
ence and survive. You wear no clothes. You can withstand the heat
because of the boundary layer, which acts like a buffering zone, a
cushion against the hot air. Heat is being conducted from the very
hot air into the cooler skin. You can remain there only a finite length
of time because, as that heat is conducted in, you get hotter and
hotter. Your capillaries dilate and you get redder and redder. Sitting
there in the sauna, you burn if you blow on your skin. The burn is
painful and can produce a blister, because you destroy the boundary
layer when you blow on the skin and you entrain hot air to the
surface.
The boundary layer, then, couples you, and any other organism,
to the air and the air temperature, to the humidity of the air, and
to the wind. The properties of the air have meaning only in terms
172
HUMAN BIOMETEOROLOGY
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of the transfer of energy across this boundary layer. Unless you con-
sider the boundary layer, the question of air temperature has no
scientific significance.
LEAF TEMPERATURE
Figure 9 shows some examples of measured leaf temperatures.
The air temperature is indicated by a solid line. Leaf temperature is
often 8 or 10°C above air temperature and has been observed as much
as 20 °C above air temperature. We have hundreds of examples of
leaf temperatures from 10 to 20 degrees above air temperature. We
made a very interesting discovery while working in the Sierras last
summer. We were measuring the temperatures of the leaves of
Mimulus, a plant that grows in water, that is, in very moist soil. Up
at timber line at 11,000 feet the air temperature was 20°C and the
leaf temperature 28°C. We took a series of measurements at various
sites along a transect down the west slope of the Sierras; we finally
reached the San Joachin Valley, where the air temperature was 38°C
and the leaf temperatures were again 28°C. If I had been asked, I
would have said the leaf temperature would be 50°C. Here was a
magnificent example of homeostasis. The leaves of this plant re-
mained cool by turning on transpiration by opening stoma and utiliz-
ing the water available to them. Now the important thing is this.
The photosynthetic rate process for Mimulus has its optimum temper-
ature at 30°C. The Mimulus plant was doing a beautiful job of keep-
ing its temperature as much as possible at the favorable position for
the rate chemistry to go on at its maximum rate. We don't know
to what extent this process is true generally throughout the plant
world, but we are trying to find out.
Figure 10 shows an idealized set of curves of the photosynthetic
rate as a function of leaf temperature and light intensity measured
in cal cm^minr1. At low temperatures chemical rate processes go on
slowly and so does photosynthesis. As the leaf temperature increases,
so does the photosynthetic rate, until an optimum temperature is
reached at which the photosynthetic rate is a maximum. At tempera-
tures greater than optimum a destructive mechanism comes into the
picture, and the molecules begin to break down faster than they are
formed. Therefore, a very rapid drop in photosynthesis occurs on the
high temperature side until a temperature is reached at which no
net photosynthesis occurs—no favorable buildup of molecules, no
generation or storage of food. Only respiration occurs, a burning up
of food. I took this set of curves to follow the daily behavior of a
plant in its climatic condition, evaluating the full energy-flow picture.
Figure 11 shows the results.
The diurnal cycles of solar radiation, air temperature, and leaf
temperature are shown, and, by use of the net photosynthesis curves
given in Figure 10, one derives the double-peaked curve for photo-
synthesis. This result is very exciting, for such twin-peaked curves
have been observed and not properly explained. A strong peak of
Gates 173
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photosynthesis occurs in the midmorning hours, followed by a very
unfavorable condition toward midday, because the leaf is too hot.
Then another peak occurs in the late afternoon. Not only are there
two peaks, but they are asymmetric. I went to the literature to
investigate this double peak, and this is what I found. During the
early morning hours in midsummer in the midwest the air gets
warmer, and the temperature and photosynthesis increase very much
in phase. The plant gets good strong light intensity at the time it
reaches its optimum temperature; but then it gets too hot, and even
though the light intensity stays high, the temperature gets substan-
tially too high. The result is that photosynthesis falls during midday.
Then in the afternoon, the sun begins to drop very symmetrically with
its morning rise, but the air temperature does not. There is a lag,
and the air stays hot until very late in the day. Then, when the air
temperature begins to fall, the light intensity has gone way down
and even though leaf temperatures now become more favorable, the
photosynthesis is low because of low light intensity. That is the rea-
son for the afternoon peak being very small and the morning peak
very strong. Figure 12 shows what a search of the literature revealed.
Some of the examples in Figure 12 are not photosynthesis,
but growth, which is closely related. When a single broad peak of
photosynthesis is shown, rather than a double peak, the curve repre-
sents cool days when the plant leaf does not become too warm. The
exciting thing is that we can relate climate, energy, energy transfer,
light, and temperature and predict some aspects of physiological
response. These are bioclimatic effects, obtained by relative climate
and physiology in a quantitative fashion.
Figure 13 shows hypothetical cases for a hot summer day and a
cool summer day. The solar radiation in the open and the solar radia-
tion in the shade on a summer day are given. If the summer day
happens to be a cool day in which the maximum temperature is just
about 20°C or if it happens to be a hot day in which the maximum
temperature becomes almost 40°C, results for the photosynthesis of
plants are dramatically different. These two days, a hot day and a
cool day, have the same amount of sunlight, which is quite possible.
If the day is cool, photosynthesis will go on at a very favorable rate.
The total accumulated area under curve 1 is the total photosynthesis
during the day and is very strong. The shaded leaf on the same day
is not getting enough sunlight. The response is quite favorable
(curve 2), but not as strong as that of the exposed leaf because of
the reduced sunlight. On the hot day, the exposed leaf (curve 3),
gets really quite hot in the sunlight; photosynthesis just gets going
strong when the leaf becomes too hot and the mechanisms are destroyed
entirely. No photosynthesis occurs throughout the midportion of
the day. Then toward evening, just before the light has disappeared,
the temperature has dropped enough to allow a little pulse of activity.
But clearly this hot day for this particular plant would be dramat-
ically unfavorable. The areas under curves 1, 2, 3, and 4 thus depict
the differences in photosynthesis for exposed and shaded leaves on
hot and cool days.
I74 HUMAN BIOMETEOROLOGY
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TEMPERATURE
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UPPER SURFACE
LOWER SURFACE
GROUND TEMPERATURE
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AIR TEMPERATURE
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Figore 9 Leaf, ground, and air temperatures as function of time of day.
Gates
175
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DATA FROM WAGGONER,
MOSS, AND HESKETH (1963)
AND LUNDEGARDH (1931)
16 24 32 40
PLANT OR LEAF TEMPERATURE, °C
Figure 10 — Net photosynthesis of corn as function of plant temperature and radiation
intensify.
176
HUMAN BIOMETEOROLOGY
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T
SOLAR RADIATION
(FROM THUT AND
LOOM IS 1944)
10,000
5,000
0000
0600
1200
1800
0000
40
35
30
25
20
I
60
50
40
30
ESTIMATED
LEAF
TEMPERATURE
s MR TEMPERATURE
(FROM THUT AND
LOOMIS 1944)
0000
0600
1200
1800
0000
#20
10
I I I
(CALCULATED PHOTOSYNTHESIS
0000
0600
1200
TIME, hr
1800
0000
Figure 11 Diurnal variation of solar radiation, air temperature, and leaf temperature and
resulting net photosynthesis for leaf. Net photosynthesis is based on curves of Figure 10.
Gates
177
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0000
0600
1200
1800
0000
0000
0600 1200
TIME, hr
1800
0000
Figure 13 — Theoretically computed diurnal net photosynthetic rates and leaf activity for
sunlit and shade leaves on cool and warm days respectively. Curves marked 1 and 2 are
for sunlit and shade leaves respectively on cool day. Curves marked 3 and 4 are for sunlit
and shade leaves on warm day.
Gates
179
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CONCLUSION
By studying climate in terms of energy, by doing this quanti-
tatively and evaluating the factors very carefully, one can get very
exciting ecological implications. If you consider a different plant that
has a different set of photosynthetic curves with different shapes and
different optima, then the plant will behave quite differently in the
same environment. When we ask questions of bioclimatic significance,
we must know for what purpose. Are we interested in photosynthesis?
In growth? In something else? We must ask specifically what we
want to know in order to evaluate the climate and its influence on
living beings.
DISCUSSION
Question: One thing that fascinates me as a chemist is the nature
of the microchemical environment (I'm not using this term in the
normal sense) of a leaf with all these radiation forces. Would this
force a pattern of chemical composition on the atmosphere immedi-
ately around the vegetation? Do you know of any work of this sort?
Answer: We are concerned about this. Recently we have worked
out, for instance, the resistance to diffusion through the stoma into
the dry air beyond. The moisture regime near the plant surface
changes as transpiration responds to the energy and light budget.
At the same time CO2 is diffusing in. So then the question is "Is a
CO2 deficiency occurring near the leaf surface?" Some work has been
done at agricultural experiment stations where they measured the
CO2 in crops and showed dramatic diurnal changes.
Question: Yes, I'm aware of these. But these changes are in a
reasonably large inter-space, aren't they?
Answer: Well, they are, but they are related, of course, to what
is happening in the boundary layer.
Question: Some people think that carbon dioxide is an air pol-
lutant and measure it as such. What is your viewpoint on that?
Answer: Well, I would never define carbon dioxide as an air
pollutant. But this depends on what you mean by pollutant. I think
that CO2 should be measured for many other reasons; it is a dramat-
ically important gas.
Question: Can you tell us about this fabulous photographic tech-
nique?
Answer: Yes. It's very simple, actually. Use a point source of
light, a concave spherical mirror, not a parabolic mirror. The mirror
forms a sharp point image at the radius of curvature. It's best if the
source is at the radius of curvature, something like 10 feet. In our
experiment the mirror was 8 inches in diameter. Then at the point
at which the image is formed, place a knife edge formed of a razor
180 HUMAN BIOMETEOROLOGY
-------
blade or sharp piece of metal. If everything is perfect, you can insert
this at the focal point, and with the eye beyond it you can see the
schlieren field.
Comment: This is the technique used in grinding lenses.
Answer: Yes, that's right. It's the same technique used for
photographing the flow of air over an aerodynamic surface. It's called
schlieren photography. It has enormous sensitivity because you have
this large optical leverage. Now with any object, say a leaf that is
warm and is giving off warm air, the index of refraction is a little
different for that warm air than it is for the ambient air around it.
The warm air bends some of those light rays, either toward or away
from the knife edge ever so little. But it doesn't take much bending
to be effective. Those rays bent toward it grow darker, and those
away grow brighter. If you adjust it in neutral shade, then the
slightest bend either way shows up beautifully. And that's why when
you just put your hand in the field of view, you can see the flow of
air. It's really dramatic. It leads to a whole new world of discovery,
of interesting problems to explore. Look at insects in this and see
what the insects are doing, butterflies, moths fanning their wings. All
sorts of heat-transfer studies can be done. This technique has quite
a lot of possibilities.
Question: Could you tell me whether the data that you obtained
from such instruments as net radiometers are applicable to your type
of biometeorological analysis?
Answer: Not exactly. We use them, but we modify them so that
we can measure the direct component of radiation. I am very much
interested in these streams of radiation individually and not in the
net. Of course you can have two strong streams of radiation in which
the net is some small value or two weak streams of radiation in which
the net is the same value. Certainly the plant is going to be very
much colder in the two weak streams than it is in the two strong
streams.
Question: Would you explain just what sort of radiation instru-
mentation you do use?
Answer: We use net radiometers that have a shiny surface on
one side. This makes them hemispherical, unidirectional receivers.
I also use the Stoll-Hardy type of infrared radiometer. We use the
Eppley type but with a polyethylene dome that we make ourselves.
The Eppley radiometer, which is very good for solar radiation, does
not measure the infrared. It does not measure anything beyond 3
microns.
Question: How do you measure leaf temperatures?
Answer: I measure leaf temperatures two ways. A very easy,
accurate way to do it is with thermocouples. The other way is with
an infrared radiometer, the Stoll-Hardy. Now the Stoll-Hardy device
was designed for use in human physiology to measure skin tempera-
^ A
Gates
-------
tures. It is a very good laboratory device, but very difficult to use in
the field. However, you can use it in the field with care. If you use it
properly, it does a beautiful job. It is simply a device that receives
the infrared radiation from the surface at which you point it. Then
you interpret the temperature from the fourth power blackbody
radiation law. We know the emissivity of plant surfaces quite well,
so not much error is introduced by the emissivity. Again I really
want to emphasize this point: when you measure temperature, ask
-what temperature means. Usually you measure not just for the sake
of temperature, but for some resulting phenomenon, such as photo-
synthesis.
Question: What would your comments be concerning objects in
the ambient air that are non-living objects, say dust particles in the
air? Are you considering chemical reaction on dust particles, absorbed
.gases, and liquids?
Answer: The first thing that you would notice is that a small
•object in the air would be at air temperature. It can't depart from
that temperature substantially, since a small object is tightly coupled
to the air and its surface-to-mass ratio is very large.
Question: What would be the range of control of heat loss by
plants in wind? You mentioned something about 5 degrees. What
control of heat loss could a plant have over that range?
Answer: Plants have considerable control over their tempera-
tures. The Mimulus plants certainly were dramatic with respect to
their temperature. When the air temperature was 20°C, the plant
temperature was 30°C. When the air temperature was 40°C, the
plant temperature was 30°C. Nearby a live oak, just a few yards
away, had a leaf temperature of 50°C when the air temperature was
40°C. The soil in which the oak was growing was not as wet, and the
oak was not physiologically constituted to transpire like the Mimulus,
which did a beautiful job in keeping its temperature down. So there
is an example of 20 degrees difference. More often the range of con-
trol would amount to about 5°C. This becomes absolutely crucial. By
the way, most desert plants are finely divided. The mesquite, the cat's
claw, all these desert plants, are fine, fuzzy sort of things—feathery
structures, right at air temperature. The Saguaro cactus, a large
succulent on the desert, is coldest in the center at noon and hottest
at midnight. This plant is designed with fins on the outside—these
fins radiate heat and do a beautiful job of staying cool. Most of the
temperatures inside the Saguaro were not very much greater than
air temperature; when the air temperature was up in the 40's, the
Saguaro temperature was 35° to 37°C. Surface temperature was
above air temperature, but only on the very thick epidermal layer.
These fins were radiating and doing a beautiful job. It was dramatic.
The desert is very thrilling from a heat-transfer standpoint.
Question: From the viewpoint of air pollution would these move-
ments around the plants have a relationship to pollution damage of
plants?
182 HUMAN BIOMETEOROLOGY
-------
Answer: Yes, they would, absolutely. And also in the transfer
of spores and plant diseases. These motions would show up dra-
matically in pictures involving air pollution and transport of spores.
The tobacco industry ought to apply this kind of analysis to the
tobacco plant and the pineapple industry to the pineapple plant,
because all plants have unique characteristics and the flow of air is
different.
183
Gates
-------
BIBLIOGRAPHIC: SEMINAR ON HUMAN BIO-
METEOROLOGY, CINCINNATI, OHIO, JAN.
14-17, 1964. Robert A. Taft Sanitary Engineering
Center. PHS Publ. No. 999-AP-25. 1967. 183 pp.
ABSTRACT: This volume is a collection of papers
presented at Cincinnati, Ohio, Jan. 14-17, 1964,
at a seminar on human biometeorology. Topics
discussed included physiological and climatolog-
ical instrumentation, climates of the United
States, altitude, microclimatology, indoor and
outdoor weather, ultraviolet light, heat exposure,
air ions, and cold stress.
ACCESSION NO.
KEY WORDS:
BIBLIOGRAPHIC: SEMINAR ON HUMAN BIO-
METEOROLOGY, CINCINNATI, OHIO, JAN.
14-17, 1964. Robert A. Taft Sanitary Engineering
Center. PHS Publ. No. 999-AP-25. 1967. 183 pp.
ABSTRACT: This volume is a collection of papers
presented at Cincinnati, Ohio, Jan. 14-17, 1964,
at a seminar on human biometeorology. Topics
discussed included physiological and climatolog-
ical instrumentation, climates of the United
States, altitude, microclimatology, indoor and
outdoor weather, ultraviolet light, heat exposure,
air ions, and cold stress.
BIBLIOGRAPHIC: SEMINAR ON HUMAN BIO-
METEOROLOGY, CINCINNATI, OHIO, JAN.
14-17, 1964. Robert A. Taft Sanitary Engineering
Center. PHS Publ. No. 999-AP-25. 1967. 183 pp.
ABSTRACT: This volume is a collection of papers
presented at Cincinnati, Ohio, Jan. 14-17, 1964,
at a seminar on human biometeorology. Topics
discussed included physiological and climatolog-
ical instrumentation, climates of the United
States, altitude, microclimatology, indoor and
outdoor weather, ultraviolet light, heat exposure,
air ions, and cold stress.
ACCESSION NO.
KEY WORDS:
ACCESSION NO.
KEY WORDS:
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