Licence: Public Domain Mark
Credit: The atmosphere in relation to human life and health. Source: Wellcome Collection.
Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.
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![tenuity of smoke particles, or of the miiiut(ist microbes, could bo under- taken, with a view to determine the rate and extent of its diffusion by human communications, it would po-obably be found that very few dis- tricts in the country are out of microbic touch, as it were, with all the chief centers of ])opulation for a single day, and none for so long as a week; and certainly the air inclosed in a packet from an infected place, when suddenly liberated, would be likely to bear with it active seeds of mischief. But the great majority of cases of influenza were due to proximity to a person already attacked. Most people in the course of a day come into association with ten or twenty others in more or less confined spaces of air. If only one in five catches the influenza, and so on in the same proportion, a fourth part of a large city may be struck down in a very few weeks. In general, one-half or three-fourths escape, being insusceptible, or less suscei)tible than others, or less exposed to the virus. AVhere large numbers of persons work together in one ill- ventilated building, the proportion of attacks is much higher, other things being equal, than where people work at their own homes. But the frequent opportunities of infection at meetings, social gatherings, public houses, in public conveyances, churches, and chapels tend to reduce the inequalities which would otherwise be conspicuous. The distance of air through which influenza can stril^e has not been well ascertained, circumstances being very different, and some forms, such as the catarrhal, being apparently more easily diffused than others. The maximum distance in the recent epidemics, for susceptible persons, could hardly have been less than 100 feet in close air, and 4 feet in the open. Isolation, where practiced, was successful in so far as it was strict. Eiut tbe intercourse of ordinary life makes isolation imi)ossible for the general poi^ulation when once an epidemic of influenza has been allowed to attack a number of centers. Strong measures against impor- tation from other countries and immediate isolation and supervision of the few cases which would occur might succeed in staving off a national infliction, for the precautionary measures would not need enforcement beyond the brief period of its prevalence in neighboring countries. !Not only the high mortality, but the enfeeblement of millions of breadwinners for months, years, and even for life has to be consid- ered in connection with the expense of preventive measures. This expense would oidy be a small fraction of the losses incurred by per- mitting the pestilence to rage unchecked. As regards weather and climate, cold is distinctly conducive to the spread of influenza, probably for several reasons: (1) The stillness which often prevails in frost; (2) the closing of windows, etc., and the closer association; (3) the greater prevalence of colds, bronchitis, etc., laying open the breathing organs to attack. The first epidemic in London, at the end of December, 1889, was ushered in by fog and frost, and api)ar- ently rapidly reduced in severity by the mild and strong winds of the latter half of January, 1890. The epidemics in succeeding years were](https://iiif.wellcomecollection.org/image/b21208724_0081.jp2/full/800%2C/0/default.jpg)
