# Popular Science Monthly/Volume 84/March 1914/The Automobile and the Public Health

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* THE AUTOMOBILE AND THE PUBLIC HEALTH
P. G. HEINEMANN, Ph.D.
UNIVERSITY OF CHICAGO
SANITARY science has done so much towards the improvement of public welfare that it may not be surprising to credit the automobile with having contributed to produce some results. The question may be asked in what directions the public health is affected by the constantly increasing use of automobiles and autotrucks. A few considerations will make it apparent that horseless vehicles may bring about far-reaching betterment in human conditions. The enormous increase in the use of automobiles and autotrucks is bound to change some aspects of city life. There are possibly three directions in which the public health may be benefited, namely: (1) the improvement of streets and roads, resulting in reducing the amount of dust in the air, (2) the disappearance of the horse and horse stables from the neighborhood of human habitations and the consequent reduction of flies and (3) the avoidance of direct infections of stablemen and veterinarians, who come in contact with horses.
There are several reasons for the statement that improved street and road pavements will benefit the public health. Bough pavements offer opportunities for the accumulation of filth and dust. The stones, usually thought necessary for horses to get a good foothold, leave holes and crevices, where dust settles and the washings of streets from rain, snow or the sprinkling cart remain until dried out. The dry material is then dispersed by winds or passing vehicles and serves as means for carrying germs. Modern improved roads, with hard surfaces and sprinkled with oil instead of water, will prevent the rising of dust in large measure; sweeping of streets will become superfluous and the atmosphere will be purer and harbor relatively few microorganisms.
One of the most serious disturbances to efficiency of sewerage systems is the accumulation of dust, detritus and street sweepings, especially after rain storms. It is obvious that this trouble may be largely reduced through the improvement in pavements, which is advocated most enthusiastically by those interested in automobiles. Societies for road improvement are in existence to-day and the number is rapidly increasing. In some states of the union a goodly number of magnificent state roads has been built and although the movement is still in its infancy, there can be little doubt of the final outcome in regard to comfort and health resulting from the construction of good roads.
​One of the missions of autotrucks will be the transferring of loading and unloading of freight beyond the city limits. The carrying of freight to warehouses on autotrucks will necessitate complete renovation of roads and construction of relatively dustless road beds. Incidentally this will also do away with much irritating smoke from locomotives. It has been stated that transportation of freight by autotrucks within city limits is economical both in time and expenditure. Improvement in city streets has followed in the wake of the introduction of electric street cars and the decreased use of horses in cities due to automobile traffic will increase possibilities in this direction.
The injurious influence of dust on the public health is of various nature. The mechanical irritation of the respiratory tract and the accumulation of dust in the lungs and eyes increase susceptibility to infections. Inflammations of the conjunctiva, due to infection with such common, usually considered innocent, germs as the ubiquitous hay bacillus, have occurred. Probably such infections follow mechanical irritation of the mucous membranes by dust or other causes. The hay bacillus is carried everywhere by dust. It must be remembered that dust is the carrier of germs—harmless as well as injurious ones. Bacteria, yeasts and molds rarely travel alone. They are generally kept in suspension by floating particles of dust. It is due to this fact that after snow and rain storms there are relatively few microorganisms in the air. Therefore any provision, which materially reduces the amount of dust will reduce the number of microorganisms in the air. Among such provisions improvement of road pavements takes a prominent place, since dust in the air can come only from the ground by the action of winds or moving vehicles.
The diseases which may be communicated by dust are manifold. The germs of pneumonia, various forms of tonsillitis, diphtheria, croup, whooping cough, colds and tuberculosis are undoubtedly carried by dust. In fact, probably all infections of the respiratory tract may be carried in this fashion. Germs of the diseases named have been isolated from the air. The germs of tuberculosis are carried chiefly by the sputum of affected persons and communicated either by inhalation of dust or by food on which germ-laden dust is deposited. It must not be understood that this is necessarily street dust, but no doubt street dust is a contributory factor.
Diseases of the intestinal tract may also be communicated by dust. Food and water, if contaminated with sewage, are the commonest vehicles of infection in typhoid fever and dysentery, but it is quite conceivable that some cases of obscure origin may be the result of dust inhalation or ingestion of raw food on which dust has fallen. Studies of typhoid fever epidemics have led sanitarians to recognize that food and water do not account for all cases and sometimes disease may be due to ​contact infection or inhalation of infected dust from the air. The infection of the saliva may then enter the system through the tonsils or the alimentary tract.
The skin of man and animals is constantly infected with many germs, some of which are responsible for boils and abscesses, erysipelas and certain diseases caused by molds or mold spores and yeasts. Dust is a factor of importance in carrying these disease germs to a place where they can invade the epidermis and bring about results which may become serious. The germs settle on the skin and await the first opportunity for multiplying at the expense of the tissues. Cleanliness is a far-reaching preventative and reduction of dust in the air promotes cleanliness.
One of the greatest benefits which will result from the increased use of horseless vehicles will be the disappearance of horses and horse stables from cities. This may not appeal to lovers of horses, but sanitary and preventive measures can not be carried out without sacrificing certain emotions. The germs and spores of lockjaw are common inhabitants of the intestinal tract of horses. Dust from dried horse manure may become the immediate cause of this dreaded and fatal disease. The spores of lockjaw germs are highly resistant and may live in the air and carry infection for months. A small amount of atmospheric dust entering a casual wound may result in serious diseaster, since a considerable portion of atmospheric dust is really dried horse manure. Another much feared disease is glanders or farcy. Horses are especially susceptible to this disease which causes a discharge from the nose, frequently looked upon in the initial stages as a cold. Carelessness may result in contact with this discharge which carries the virus and by means of abrasions of the skin of the stableman, rider or veterinarian the infection may be communicated. Glanders usually terminates fatally. Cases of this nature are by no means scarce. Both lockjaw and glanders will become less frequent with the disappearance of horses from our streets.
In some states and municipalities war has been declared upon the fly. There are at least two species of flies which interest us in this consideration, namely the house fly and the stable fly. It has been recognized that flies may carry disease germs and thus become important factors in spreading infection, not to take into account the discomfort, caused by flies, to man and animals. In The American Journal of Public Health of December, 1913, is reprinted part of an article of the September number of the Department of Public Safety of Rochester, N. Y., giving some interesting figures on manure production and its relation to the fly problem.
The campaign against flies is based on study of the life history of the fly. These studies have demonstrated that manure is one of the commonest places for fly breeding. A comprehensive book on this subject has been published by Edward H. Boss, entitled: "The Reduction of Domestic Flies." Some of the following statements are taken from this book.
The house fly breeds in all sorts of filth, but stable manure is the commonest lair for the insect. The female fly likes to lay her eggs here and in horse dung the fly maggot or grub lives for five days and then becomes the chrysalis or nymph. After about five days more the fully developed insect emerges to become a nuisance and do its deadly work. Fly reduction is a beneficial measure because it brings about a saving of life; reduces sickness, sorrow and misery; results in riddance of a pest and facilitates sanitary inspection. It has been estimated that one fly can produce in one month 506,250,000 offspring. Supposing only one half of these survive the larval stages, we have the enormous total of 250,000,000 increase per month.
The author of this book also states that "In the West End of London the stables and mews have become garages and there are only a few flies, where formerly thousands pestered, . . ." The disappearance is due, in part at least, to the removal of the horse manure and with it the favorite breeding places for flies. The campaign against flies, therefore, consists largely in prompt disposition of horse manure. That the most efficient method of disposition is the removal of the horse is obvious and with the advent of horseless vehicles the horse becomes superfluous. Considerable success has already crowned efforts in caring for the excrements of horses and the banishing of horses from our streets will facilitate this work. With the consequent reduction of flies we shall rid ourselves of a disgusting pest and aid in the preservation of life, health and happiness.
Evidence of the role played by flies in carrying infection is not wanting. In the Spanish-American war much of the typhoid fever was ascribed to the presence of flies. They were so common that, when cooked food had cooled sufficiently, it was covered with flies. When eating the men had to keep the flies away with one hand. Fecal matter in the pits was covered with lime and the white specks from the feet of flies could be traced on food. Virulent tubercle bacilli, the germs of typhoid fever, of bubonic plague, of anthrax and of Asiatic cholera have been found on the feet or in the intestinal canal of flies. Infection of ​milk by flies is a common occurrence. Hundreds of bacteria have been counted on the feet of flies caught in the cow stables.
Some sanitarians believe that many infant lives would be saved if the fly could be kept away from the baby's milk. A recent investigation in New York City carried out by Dr. Donald B. Armstrong (published in the Journal of the American Medical Association, January 17, 1914,) seems to show that there is some connection between flies and infant mortality. The author's results seem to indicate that the fly is a much neglected factor in the etiology and transmission of summer diarrhea. He thinks that greater attention should be given to the elimination of the insect by all those interested in prevention of infant mortality. Two areas were covered by his investigations, both practically alike in population and other conditions. The first area was subjected to every possible precaution against flies. The means were educational campaign, exhibition of picture films of flies in a nearby theater, screening of the 1,700 doors and windows, and placing of large fly traps in the courtways, yards and stables. The second area was permitted to pursue its usual insanitary course. In the protected area the total days of sickness of diarrheal diseases among infants was 273, in the unprotected area 984.
According to Farmer's Bulletin 540, U. S. Department of Agriculture, the stable fly, also known as the wild fly, the straw fly and the biting house fly, commonly breeds in horse manure, especially if straw is present, as is usually the case. It has been believed, although lacking confirmation, that infantile paralysis and pellagra are communicated by this species. It has been more definitely demonstrated that this fly is instrumental in spreading some diseases of domestic animals. Aside from these facts it is a tormentor of live stock. Horses and cattle suffer more than other animals, but sheep, goats, hogs, dogs and cats are known to be infected by these flies. Even man is not immune. A tropical disease of camels, horses and cattle, known as "surra," is communicated by this fly. Anthrax, glanders and possibly other diseases of cattle, also communicable to man, may be transmitted by the stable fly. Although the chief breeding places are straw stacks, the manure piles commonly found near stables where horses are kept furnish suitable breeding places. Adult flies may follow for considerable distances traversing roads and, when engorged with blood, settle on nearby objects. Other teams passing along the same highways are subsequently attacked. It is evident that with the reduction of horses and horse stables this pest will be greatly reduced.
Flies do not generally act as intermediate hosts in the transmission of disease. Usually they carry the germs on their feet or in the intestinal tract and infect food by walking over it or dropping on it. The danger from flies is greater than from mosquitoes. The latter act as intermediate hosts and carry the virus of malaria, yellow fever and other diseases. ​The germs of these diseases undergo a well defined cycle of development in the body of the mosquito. For mosquitoes to become a menace it is necessary for them to bite a human subject suffering from malaria or yellow fever after which a period of incubation has to elapse before the bite of the insect becomes dangerous. This incubation period lasts somewhere from ten to twelve days. Direct infection by mosquitoes as mechanical carriers of germs is relatively scarce. Besides, mosquitoes are not universally susceptible to the diseases mentioned. Only certain species can act as intermediate hosts. Since flies are mechanical carriers the possibilities of infection by these insects is greater than by mosquitoes.
The probable benefits that will result from the increased use of automobiles and autotrucks may be summed up as follows: (1) With the universal construction of smooth and non-absorbent roads and the use of oil instead of water for sprinkling, the quantity of dust in the air will be reduced. As a consequence a number of diseases which are frequently transmitted by dust will be decreased and storm waters will be more easily cared for. (2) The horse will gradually disappear from our streets. With it the number of house flies and stable flies will be diminished; human lives will be saved and much added to health and comfort. Contact infections of those engaged in the care of horses will also become rare. At the same time out of door life and enjoyment will be encouraged and thus a further contribution to the betterment of human conditions brought about.