ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 273 



Consumption or tuberculosis is most prevalent where the air is moist 

 and the daily range of temperature large. 



Typhoid or enteric fever is most common in the autumn and much less 

 prevalent in May and June. There is a sharp decline in its prevalence 

 in London in December. In New York, and in large towns in Europe, 

 the maximum is decidedly apparent in late summer or autumn. The 

 variation of prevalence according to season seems to show a distinct 

 connection between the development of the bacillus and the tempera- 

 ture of soil and water, and considering the long incubation and dura- 

 tion of cases the maximum of infection must take place at the very 

 time when the temperature of the soil at 1 or 2 feet deep is about at its 

 highest. 



Cholera, diarrhea, yellow fever, and malaria, the poison of all of 

 which arises from the soil and surroundings into the air, are much 

 more prevalent in the hot season and in hot countries. 



CONDITIONS OF INFECTION THROUGH THE AIR. 



In order to obtain a true conception of the manner in which the 

 virulent matter of infectious diseases may be conveyed through short 

 distances of air, either directly from a patient or indirectly from objects 

 which have become infected, we have to consider those cases in which 

 susceptibility is greatest, for these afford the truest criterion of the 

 capability of the survival of pathogenic microbes, and the best meas- 

 ure of the precautions which should be adopted to exclude not only 

 persons of average susceptibility, but the most susceptible, from the 

 area of danger. In cases of pyaemia, of puerperal fever, and of small- 

 pox, not only ordinary measures of disinfection, but abstinence from 

 attendance on susceptible persons for some time, is recognized as 

 needful. In cases of influenza, diphtheria, and scarlet fever less care 

 is exercised, except in regard to certain susceptible states. In all of 

 these diseases, however, transmission is far too frequent, and as a mat- 

 ter of fact the required precautions are not duly observed. The strict 

 regulations of dress and washing enjoined upon nurses are almost 

 equally applicable to medical attendants, and the use of clothes of a 

 washable material and smooth surface by all persons in the presence of 

 infectious cases would give greater security to all patients visited, and, 

 indeed, to the general population. A square inch of cloth can easily 

 hold upon its surface 10,000,000,000 microbes of influenza, so that it is 

 quite conceivable that a man may carry on his clothes many more of 

 these organisms than there are inhabitants on the globe, and that 

 many scores of thousands of these pass into the air of every room 

 which he visits. 



Similarly, in the cases of other diseases which pass largely by the 

 breath and by deposited particles, there must always be a certain num- 

 ber on every person who visits the sick room, and although the majority 

 of people fall victims only to rather large numbers or a high degree of 

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