Following a review of the physiological principles
involved in the regulation of body temperature and of the
various ways in which the body is known to react when it
is exposed to abnormal degrees of environmental heat, a
"working" classification has been proposed in an attempt to
clarify these heat effects syndromes. The terminology used
was based on names hallowed by tradition, but modified in such
a way as to illustrate the aetiology and principal clinical
features of the syndromes. It was not claimed that the
classification should be the definitive one, because of
certain deficiencies in knowledge.Then, following a consideration of the different types
of climate in which heat effects syndromes are known to occur,
the expected distribution of thes syndromes according to
climatic conditions was deduced. This hypothesis was shown
to be correct by personal experience and a shady of the reports
of the experience of other observers.A detailed study of the syndromes illustrated the importance of the different factors contributing to "climate ", but
also demonstrated the difficulty in assessing their relative
contribution. This was sometimes increased by the fact
that environmental conditions cannot always be accessed from
observations made by conventional methods, since these may be
very remote from actual living and working conditions. Whilst
the relationship between dry bulb temperature and heat stroke is fairly obvious it has been clearly demonstrated that the
minilLuIL dry bulb and the wet bulb temperatures are also very
important factors in the aetiology of some heat effects
syndromes, although their exact contribution in particular
syndromes has been difficult to assess from the data available. This was well illustrated in the discussion on
anhidrotic heat exhaustion (Chapter 11), and in particular
in the interpretation of the significance of the changes
in the minimum dry bulb and wet bulb temperatures associated
with the abrupt cessation of the epidemic of this syndrome
at Karachi in 1946 (figure 6). There is no doubt, however,
that the wet -bulb temperature, long known to nave a great
influence on comfort sensation and ability to work in hot
environments, makes a definite contribution to the aetiology
of some heat effects syndromes.It has also been shown that certain climatic factors,
including the wet -bulb temperatures, are important in the
aetiology not only of prickly heat (a condition of much
greater importance than has hitherto been appreciated) but
also of other skin diseases.Important deficiences in knowledge have also been revealed and suggestions made for their remedy, but it has been
pointed out that experiments conducted in artificial environments have a limited application, and that further studies in
the field are also necessary to clarify the outstanding problems
