The underground atmospheric working environment of the
Rand mines is hot and humid, and in some cases associated
with stagnation of air. Hard manual labour in such conditions may produce pathological reactions, namely, Heat-collapse and Heat-stroke.Heat-collapse is due to cardiac embarrassment brought about by the inability of the heart to cope with the increased
physiological demands made upon it by the work and the
environment. The symptoms and signs are those of a fatigued
heart, namely, headache, dizziness, general feeling of weakness or collapse. The discomfort that these symptoms produce prevents further muscular work and therefore saves the
already overworked heart from still further effort. Heat-collapse is therefore in a sense protective.It is only natural that workers who are debilitated as
the result of disease are more prone to heat -collapse than
normal healthy subjects. Further, the abnormal strain put
on the heart, as the result of work in bad underground environment, 7hich normally produces symptoms of heat-collapse,
may in diseased subjects be sufficient to bring about a complete breakdown of the heart's action with subsequent death.Heat-stroke is a condition of acute mental excitement
with delirium, convulsions, muscular twitchings or tremors
and is always associated with a high body temperature. The
actual causative agent in the body which precipitates this
condition has not yet been established. Hyperpyrexia is
merely an accompaniment of the general bodily derangement
and is not the causative agent. The invariable absence of
diagnosable disease in cases of heat - stroke on admission to
hospital, and the subsequent similar findings by Macro- and
micro- pathological examination in cases that terminate
fatally, is consistent with the fact that co-existing disease does not play a role in precipitating heat-stroke. Unlike heat-collapse, heat-stroke only occurs in unacclimatised subjects. Owing to the acute onset and course of the
affliction, treatment directed at anticipating an attack is
impossible.Heat-stroke is preventable. Adequate control of the
cooling power of the working environment together with a
suitable form of underground acclimatisation will eliminate
it
