PHYSICAL BIOCLIMATOLOGY 
correlation with a weather phenomenon is difficult to 
detect because the time lag between the given phe- 
nomenon and the first manifestation of the disease is 
unknown and perhaps variable; furthermore, almost all 
investigations have been made in central Europe and 
in the northern United States, that is, in regions where 
changes of air masses are too frequent to correlate one 
onset of illness with one front only. A number of the 
pertinent investigations have failed to meet statistical 
requirements. 
According to Petersen [65], different fronts have 
different effects: cold fronts cause “anabolism,”’ contrac- 
tion of blood vessels, spasms, and biochemical reduc- 
tion; warm fronts produce the opposite effects. Simi- 
larly, Curry tried to classify his patients into those 
sensitive to warm fronts and those sensitive to cold 
fronts [10, 29, 30]. A premonition of the weather, to- 
gether with the foehn sickness, was explained [36] by 
the theory that descending air currents produce trigger- 
ing action, particularly in the case of rheumatic attacks. 
The weather effect demonstrated by fronts may be non- 
specific [69]; it may be a remote effect or, most probably, 
it may be caused by admixtures to the air. Pressure 
variations of all frequencies were found to be without 
effect [81]. On the other hand, the foehn illness could be 
avoided by purification of the air [81]. The decisive 
agent was assumed to be the oxidizing power of the air, 
the “Aran” [29, 30] (essentially ozone), which is brought 
down from high altitudes by descending air currents 
and perhaps produced by electric discharges. According 
to this, one could expect no causal relationship with 
fronts, but only a statistical relationship. The “Aran” 
hypothesis remains to be verified. 
The vast number of publications in the past on effects 
of the static electric field of the atmosphere and of the 
terrestrial magnetism on man have not survived more 
recent critical tests. The daily occurrence of contact 
and friction electricity during extreme dryness, such 
as in heated rooms in winter, causes uncomfortable 
electric discharges and may occasionally cause an ex- 
plosion of gasoline or ether vapor. 
Theoretical calculations and some clinical results in- 
stigated the hypothesis of certain effects of inhaled 
atmospheric ions on man. Beside enhancement of spe- 
cific electrochemical effects of the inhaled nucleus, a 
charge of the alveolar wall by unipolarly charged and 
absorbed ions may be anticipated. Open-air tests did 
not yield a reliable correlation coefficient between the 
number and unipolarity of large atmospheric ions or any 
other electrical factor of the inhaled air and the human 
health. 
The very interesting correlation between sunspot 
activity and mental diseases, suicides [32-34], gesta- 
tion eclampsia [6], the sedimentation rate of the 
healthy male blood serum [82], cholera in Russia, and 
meningitis (for a summary see [67]) belong in the field 
of bioastrophysies unless a meteorological agent can be 
found as an intermediate factor. 
Aviation Medicine [3, 39, 48, 76]. At high altitudes, 
or on mountains, man is subject to specific effects of 
1121 
oxygen partial pressure and of changes of air pressure. 
Additional effects stemming from heat or cold, radia- 
tion, stress of flying or mountain climbing, acceleration, 
ete., might be aggravated by the effects of pressure. 
The blood, as the carrier of fuel and oxygen, must 
attain at least an 80 per cent saturation with oxygen in 
passing the lungs. To accomplish this, an oxygen pres- 
sure of 80 mb must prevail within the lungs, a fact 
which in turn presupposes a 133-mb oxygen pressure of 
the inhaled air. Ordinarily, 63 mb of H.0, 53 mb of 
CO2, as well as the Ne pressure, have to be added to 
account for a real picture of the air inside the lungs. 
At an average height of 3.5 km, the external O» 
pressure assumes the value of 133 mb. Above this 
level, a nearly complete physiological compensation is 
provided through various countermeasures: increase in 
breathing, increase in the amount of the oxygen-carry- 
ing vehicle (blood), and decrease in the alveolar COz 
pressure. 
Below 96 mb Q2 pressure (above 6 km of height), 
these compensations fail in a nonadapted man and the 
“engine” stops owing to lack of oxygen. 
If pure oxygen is breathed, the afore-mentioned crit- 
ical partial pressures of oxygen are reached at altitudes 
as high as 11.8 km and 14 km, respectively. For this 
reason, pressurized cabins are indispensable above these 
heights, even for a crew breathing O2 by use of masks. 
The reduction in barometric pressure in itself may 
cause discomfort and distress due to the expansion of 
gases trapped in body cavities (ntestines, dental cavi- 
ties, sinus). 
Nitrogen is physically dissolved in the blood accord- 
ing to the existing partial pressure (Henry’s law). Sub- 
sequent to a fast ascent to heights above 8 km, this 
N. tends to degasify from the blood, forming small 
bubbles which provoke pain in the joints and may 
even affect the brain. Owing to the hydrostatic pressure, 
the lower organs are usually less affected. These symp- 
toms are known under the name “‘aeroembolism.’’ The 
N, in the blood may be replaced by O2 or He to prevent 
aeroembolism [48, 79]. 
A sudden drop of pressure may be caused by rupture 
of a pressurized cabin at great heights. This drop causes 
rapid expansion of the air in the lungs. This “explosive 
decompression”? may even damage the walls of the 
lungs. 
Space Medicine [4, 5, 23, 47, 52, 53, 77]. Space 
medicine comprises the human factor involved in flights 
beyond the lower stratosphere and in flights along 
trajectories equivalent to those of a celestial body. The 
main problems of this new field are: 
1. With increasing altitude the protective atmos- 
pheric filter will gradually be lost. First solar X-rays 
are encountered at 100 km, but the existence of hard 
components, able to penetrate the hull of a craft, is 
dubious. Effects of cosmic-ray showers and of cosmic 
radio waves on man are being considered, but they are 
not very likely. Biological effects of cosmic-ray pri- 
maries prevalent above 25 km may be of prime impor- 
tance. In passing through tissue, they produce very 
