Part 2

Likewise in Westminster the number of days of fog averaged 27 per year for the lustrum 1902-1906, and 17 per year for the period 1907-1911. The improvement shown above is due, in large part, to the increased use of gas and electricity and to better stoking (Kershaw, Russell). On the other hand, if we turn to Pittsburgh where the amount of smoke has been on the increase in recent years, we find that the number of days of fog increased from an average of 22.6 per year for the first five year period to 50.2 for the second five year period, 1907-1911.

Not only is smoke related to the frequency of fogs, but it also increases both the duration and the density of fogs. The water globules become coated with a film of black, sticky, tarry soot which retards evaporation. These soot fogs, or “pea-soup” fogs as they have often been called because of their grimy opacity, may at times become practically impervious to the luminous rays of the sun. Even in one of the lighter varieties of fogs the soot products may increase seven fold. Many average soot-fogs reduce the amount of light one-half. On an exceptionally dark day in Berlin the light was only 1/500 of what it was on an ordinary overcast day and only 1/3000 to 1/4000 of what is was on an entirely clear day (H. H. Kimball). The smoke in the center of Leeds on an ordinary day absorbs as much as 25% of the total daylight as compared with the suburban sections of Leeds, or 40% as compared with the suburb of Garforth, which is 7 miles distant (4).

That smoke must materially decrease the limits of visibility is patent from what has been said. The limits of visibility vary with the number of dust particles in the air: 1,000 particles per cu. cm. render large objects like mountains invisible at a distance of 100 miles; 100,000 particles render them invisible 1 mile away, and 1,000,000 particles 1/10 of a mile distant (Aitken). Smoke not only fills the atmosphere with countless numbers, but with extremely opaque particles. These particles may unite with globules of water and this makes the atmosphere still more opaque. As was stated above, in large cities even in fine weather there may be over 300,000 particles per cu. cm., as against a few hundred in the country. Accordingly, we find in London that the limit of visibility in the winter time, even during the clear part of the day, does not exceed one-half mile.

The temperature readings are somewhat unsatisfactory because they usually include only the maximum and minimum records for each day. Minimum temperatures are found to be perceptibly higher in the cities than in the country, partly because of city heat, but chiefly because the smoke blankets prevent the escape of the heat at night. In Pittsburgh the minimum temperature averages about 4° higher than the temperature in the adjacent stations (Kimball). In the day time the upper surface of the smoke clouds absorbs portions of the sun’s heat, and this inevitably lessens the heat on the ground surface. The solar energy has been reduced 40% by smoke clouds (12), and it is possible that very little heat penetrates to the earth’s surface during a very dense smoke cloud. In London the surface temperature during a given reading was 44° F., while 59 ft. directly above it was 51.5°, a difference of 7.5°. Between 9 A. M. and 3 P. M. the surface temperature rose 7.5°, while the roof reading rose 16.5°, or more than twice as much. Although thoroughly satisfactory data are not available it is undoubted that smoke (which is most abundant in the atmosphere in the winter time, owing to lessened convection) lowers very perceptibly the diurnal winter temperature in smoke-producing cities.

Finally, smoke indirectly affects the electrical potential of the atmosphere. I know of no direct study of this question, but it is possible that smoke causes a decrease in the potential because it tends to increase humidity. An increase of humidity decreases the potential (save possibly during fogs, as noted later, 14). We are also told that the potential increases with the turbidity (Trubung) of the atmosphere, and consequently with high barometric pressure. Since smoke tends to decrease the diurnal temperature, particularly in the winter time, it apparently tends to increase the diurnal potential, as the potential decreases with increasing temperature (14).

Having thus discussed the atmospheric changes caused by smoke we now turn to the second question. How do the various smoke-induced weather states affect the mental and bodily health and happiness of human beings? It is evident that the problem can be formulated largely in terms of sunshine dynamics. On the one hand, we have the psychic and physiological influences of positive states of sunshine: brightness, luminosity, warmth, dryness, the presence of the infra-red, spectral and ultra-violet rays, and high electrical potential (because of dryness). On the other hand, we have the effects of the negative states: gloom, darkness, cloudiness, fogginess, rain, moisture, cold and low electrical potential. It is utterly impossible to separate all of these components, and it will, therefore, be no easy task to measure the influences of each component.

Literature, both poetry and prose, contains frequent allusions to the alleged effects of sunshine or the absence of sunshine on the feelings of man. Charles Lamb “felt himself immortal” and “a great deal taller” on bright days. Moore took delight in sitting in the sunshine:

“Blessed power of sunshine! genial day, What balm, what life are in thy way! To feel thee is such real bliss, That, had the world no joy but this, To sit in sunshine calm and sweet, It were a world too exquisite For man to leave it for the gloom, The deep cold shadow of the tomb.”

Byron felt “more religious on a sunshiny day,” Pope refers to “the soul’s calm sunshine,” Rousseau sat with bared head in the sun; Shelley so coveted the most intense sunlight that he did his writing from the roof, while it is a common observation that people generally, and particularly the aged, instinctively seek the sunshine. Mrs. Hemans wrote a rapturous apostrophe to the sunbeam:

“The sunbeam of summer O! what is like thee; Hope of the wilderness, Joy of the sea.”

Many writers cannot do satisfactory work unless the weather fits the mood, motive or scene; unfavorable weather states cause a disagreement in the thought processes(27).

Southey refers to the depressing influence made upon him by the “vile, dark, rainy clouds” of Great Britain, when he returned from a sojourn of 15 months in sunny Italy, where his brain was in a state of high illumination. An Italian proverb runs thus: “Where comes no sun the doctor comes.” Similarly a German saw: “The funeral coach turns twice as often on the shady side of the street as on the sunny side.” J. Ashby-Sterry has dwelt upon the demoralizing effect of the London fog:

“A London fog when it arises All London soon demoralizes.”

“It chokes our lungs, Our heads feel queer, We cannot see, we cannot hear! So when this murky pall drops down, Though dearly loving London town, We feel we cannot quite revere A London fog.”

Likewise Walter C. Smith:

“A grey fog in the early prime, A blue fog by the breakfast hour, A saffron fog at luncheon time, At dinner a persistent shower Of smut, and then a dismal power Of choking darkness and despair, Thickening and saddening all the air.”

A special questionnaire investigation on nephelopsychosis made some years ago by G. Stanley Hall and the writer (9) indicated that heavy black clouds and fogs may often strike fear or terror into children, or may make them feel depressed and gloomy or restless. Some children experience “terrible fear” at times and others feel that “something dreadful will happen when the horrible black ones appear.” There are cases on record of actual motor paralysis caused by terrifying clouds. There is here an interesting parallelism between the emotional responses called out by clouds in the children of to-day and the responses called out in primitive races. In his mythopoetic tendency primitive man read fear and danger in dark clouds, particularly the black thunder clouds. The smoke clouds of our city probably depress children just as any dark clouds do, and when particularly black may also arouse nephelophobias.

Sir Archibald Geikie has ascribed the subdued, grim character of the Scot to the gloom of his valleys and the canopy of cloud “which for a large part of the year cuts off the light and heat of the sun.” The French formerly regarded the Englishmen as “rude, unlettered ... surly, ill-conditioned men, having lived in an unhappy climate where perpetual fog, only varied by rain, prevented the sun from ever being seen, suffering from so deep and inveterate a melancholy that physicians had called it the English spleen, and under the influence of this cruel malady constantly committing suicide, particularly in November, when we were well known to hang and shoot ourselves by the thousands” (2).

On the other hand, there are those who believe that the monotonous gloom of England has inoculated the Britain against moods of depression and hypochondria, and made for the evenness of temperament which is said to characterize him (18). Gloomy weather would thus serve as a catharsis against the very depressions which it is said to induce. I must confess that this reasoning seems to me to be quite specious. The effects of meteorological monotony, particularly of depressing states, probably do not differ from the general effects of physiological or psychic monotony: narcosis, hypnosis, fatigue, overstrain, distaste, or aversion. However that may be, there can be no doubt that many persons experience an exhilarating, tonic effect on a bright, sunshiny day and a depressing influence on gloomy days--assertions that have, indeed, been ridiculed by Dr. Johnson. Fortunately these impressionistic views on the buoyancy of sunshine and on the depression of gloom (particularly cold or hot, damp, dark days) find a certain degree of support in scientific studies.

Deprived of sunshine the human skin assumes a pale greenish hue, like the skin of the people in the polar regions. This is probably due to the absence of the blue and ultra-violet rays of the sun which dilate the blood vessels and bring the blood to the surface, and to the absence of the infra-red rays which are associated with heat. Sunshine promotes transpiration and perspiration, and thus favors the elimination of toxic products through the skin. Bright, sunny days lessen the strain on the kidneys.

The amount of blood and the per cent. of hemoglobin are increased by sunlight and decreased by darkness. Oerum, in an experiment on animals, found that light increased the quantity of blood 25% in 4 hours. Likewise Grawitz and Graffenberger have observed a diminution in the quantity of blood in animals kept in the dark, while Marti found under similar conditions that the number of red blood corpuscles was lessened (13). There is thus a loss of red coloring matter in the blood of animals kept in the dark. The well-known baker’s anemia points to the same impoverished state of the blood in night workers (Gardenghi, 13). Not only so: in an examination of 29 persons Finsen (7) found less hemoglobin in the winter than in the summer, presumably because of the diminished sunshine in the winter time. Diesing suggests that the lack of sunlight in northern countries is an essential factor in the causation of rachitis. The rays of the sun--specifically the blue and ultra-violet rays--thus exercise a tonic or stimulating action on the organs of circulation, transpiration and elimination, and very probably also directly stimulate the nervous system. Finsen has shown that benumbed or apparently dead insects have been revitalized by the application of ultra-violet rays. It is doubtful whether this stimulating effect is due to increased electrical potential, as argued by Dexter (5), because the more intense the sunshine and the higher the temperature the lower is the potential (14). The stimulating effect is probably due to the chemical action of the short rays of light. These rays probably penetrate the deeper tissues of the body just like the X-rays. It is well known that persons suffering from chronic joint disease, particularly from joints affected with tubercular sinuses, can be greatly benefited or entirely cured by constantly exposing the affected limbs to the direct rays of the sun. Guggenbuhl, it will be recalled, attained some success in the treatment of cretinism simply by removing the cretins from the dark Alpine valley to the sunlit summit of the Abendberg.

Because of the stimulating effect of sunshine, may not an excess of sunshine be just as detrimental as a deficiency? It has, indeed, been assumed that the climatic dangers of the tropics are largely due to the injurious tropical sunlight, particularly to the abundance of the ultra-violet rays. Woodruff holds that the failure of the white race to colonize in the tropics is due to the excessive light, and not to the heat and humidity. The light, he contends, tends to produce ennui, neurasthenia and ultimate collapse in blond persons (26). This conclusion is not sustained by recent investigations. Experiments have shown that monkeys do not succumb from insolation in the tropical sun if care is taken not to allow the bodily temperature to rise, by conducting away by brisk air currents the excessive heat (Aron, 23). The injurious quality of the solar light is thus due to the infra-red and not the ultra-violet rays. The white man can secure adequate protection in the shade from the heat rays, and by wearing white clothing he can be adequately protected from the ultra-violet rays.

Whether the retinal excitation by the sun’s rays exerts any stimulating influence is not known. It is known, however, that red colors are stimulating. They excite some animals (for example, cattle, frogs and turkeys) and increase muscular strength. Thus Fere obtained the following strength records: with ordinary light, 23 units; with blue, 24; with green, 28; with yellow, 30; and with red, 42 (29). Colors, as is well known, possess marked affective qualities, due not merely to the affective tone of the sensation and the sense feeling, but to the affective elements of consciousness, namely associations, emotions and sentiments (29). That sunlight does exert psychic influences apart from any specific retinal influence is a matter of common experience. Nevertheless, the most important visual influence of sunshine is perhaps not the emotional satisfaction, cheer or exuberance which it engenders, but the optical value of good daylight. Daylight is relatively colorless because it contains both chromatic and achromatic light. A bright colorless illumination is best from the standpoint of visual efficiency, health and affective quality. It is less fatiguing than a colored light or than intense or dull artificial light. Electric lights are often too intense because of the proximity of the light or because the rays are thrown directly into the eyes or directly upon the object under observation. They thus over-stimulate the sensitive layers of the retina, and this may cause degenerative changes. Mercury vapor lamps and old Welsbach burners emit a greenish flame whose affective quality is very disagreeable to many persons. Many of the gas jets in common use, unless equipped with incandescent burners, not only give a weak flickering, dirty yellowish light, which is extremely fatiguing and irritating to the eyes, but they also vitiate the air of the living rooms, particularly in the homes of the poor in the winter time. Add to these difficulties the further fact that by habit and association we have learned to base our visual estimation and discrimination of things on their appearance in broad daylight, and we begin to appreciate the baneful optical effects of the frequent obscuration of the sun by smoke clouds, by smoke-produced water clouds and fogs, and by the filling of the atmosphere with opaque particles. As stated before, particles in the air and fogs may reduce the limit of visibility from one mile to less than one city block. During the dark days which are common in manufacturing cities the lights must be kept burning in the homes, schools, shops and factories--anywhere, in fact, where close eye work must be done--all day. Almost always the lights must be turned on very early in the evenings. Very frequently the intensity of artificial illumination does not meet the requirements of visual health. Aside from this, artificial illumination entails a considerable economic loss. Worse still is the condition of those who, through financial limitations, must work in the dark gloom of smoky days without the aid of artificial light. The writer has shown in a special experiment on the visual estimation of distances that bright objects are judged to be nearer the observer than similar black objects when placed at the same distance (25). This being the case, it is evident, as indeed common observation indicates, that anything on which the eyes must be fixated in darkened illumination will be imperfectly envisaged. To overcome this optical handicap, there is a strong tendency to move the object too near the eyes. If done repeatedly this entails a severe strain on the muscles of accommodation, causing increased muscular fatigue, which may result in muscular paralysis, imbalance or dioptric distortions. On the other hand, by illuminating an object with good daylight it will be made to appear nearer to the eye. The result is that objects will actually be held at a further distance and distant objects will be seen without eyestrain. If an investigation could be carried out on a large scale with sufficient accuracy, it is possible that a greater prevalence of myopia, myopic astigmatism and other eye disorders would be found in densely smoky cities than in smoke-free cities, so that a positive correlation would be found to exist between eyestrain or certain eye disorders and atmospheric smoke.

Dark days repress the infra-red rays and thus diminish solar energy. In fact, on excessively smoky days only a small amount of solar heat penetrates to the earth’s surface. This circumstance may be rather welcome to man during the excessive heat of the summer (although objectionable to plant life), but during the winter time it may cause much misery, particularly among the poor, because of the excessive diurnal cold during this season (smoke clouds elevate the nocturnal temperature). It is also possible that the reduction of the heat profoundly affects the habits of the community. Thus Dexter (5) has shown that low temperatures (10°) produce an excess of drunkenness amounting to 38%, while high temperatures (85°) decrease drunkenness to the extent of 40%. High winds, which lower the bodily temperature, also increase dissipation. The increased tendency to dissipate probably results from an attempt to seek forgetfulness from misery in alcoholic narcosis, or from an attempt to artificially elevate the body temperature by indulgence in drink.

Dark days exert a particularly sinister influence upon working people. One factory head has ventured the opinion that a disagreeable day yields about 10% less in labor returns than an agreeable day. During human labor the chemical products of activity are greatly augmented. The amount of carbon dioxide given off during a day of work is nearly twice as much as during a day of rest. Observations on the embryos of frogs also indicate that more carbonic acid is given off when it is light than when it is dark (Moleschott). Therefore, merely reasoning from these premises, it would appear that the bodily waste products from muscular activity, and probably also to a lesser extent from mental activity, are more injurious on dark than on bright days. Not only so: dark, sunless days are likely to be moist, rainy or foggy. During foggy days particularly the poisonous gases are unable to rise because of the atmospheric stagnation that obtains during fogs. On these days the amount of carbon dioxide may sometimes be increased from 200 to 300% as compared with clear days. Dexter (5) attributes the devitalizing, depleting effects of fogs to lowered electrical potential. He regards atmospheric states of high electrical potential as stimulating and vitalizing to animal life. But it has not been conclusively shown that the electrical potential is decreased during fogs. On the contrary, it is maintained that fogs, especially thick, winter fogs, usually raise the potential (14), while the low ground fogs in late summer and fall have been found to lower the potential. But then, again, Chauvenau found that thick, city fogs exercised no influence on the electrical potential. It has, therefore, not been proved that lowered electrical potential has anything to do with the depleting effects of fogs; but I am of opinion that the suppression of the tonic chemical rays of the sunshine is an important factor.

Again, moisture in the atmosphere may become very injurious because it absorbs the poisonous exhalations of living organisms. Hence the air which must be breathed on moist, dark days is liable to be surcharged with toxic waste products which poison the individual.

The effects of moisture _per se_ vary with the temperature. During warm, moist atmospheric conditions there is diminished evaporation from the lungs, fewer red corpuscles (because there is less oxygen in the air), increased tendency towards intestinal troubles, lowered resistance, and greater mental and bodily fatigue and prostration; while during cool moist weather catarrhal, respiratory and rheumatic affections are aggravated (3, 26).

It has been observed that changes in the density of moisture affect the sensitivity for odors, tastes and touch. Tea-tasters do their best work on fair days (11).

That the electrical potential decreases with increase of humidity has, apparently, been established, except under conditions of fog. It we grant that a state of high electrical potential stimulates and energizes the organism, then a part of the devitalizing effect of humid days must be ascribed to a lessened potential.

Not the least detrimental effect of the dark smoke strata of our cities is the fact that they intercept the bactericidal rays of the sun, namely, the blue and ultra-violet rays. These rays either check the growth of, or completely exterminate, various kinds of pathogenic bacteria (1, 6). Their deadly effect on the tubercle bacilli is universally recognized. Indeed, as Sternberg points out, sunlight is one of the most potent and one of the cheapest agents for the destruction of pathogenic bacteria. Less diseases are found during sunshiny than foggy or cloudy weather, while the death rate increases considerably during fogs. Thus during a November fog in Glasgow the death rate rose to 13.9 while in other Scotch towns free from fog it was only 3.3. But the increase in the mortality is not merely due to the fact that the sunless, foggy states lower the temperature and favor the growth of micro-organisms, but the water globules absorb particles of dust and acrid smoke and the toxic products of respiratory waste. (In factories dust particles become vehicles for the products of human fatigue.) The inhalation of these products irritates and poisons the mucous membrane. Moisture is particularly injurious in cases of pathological nasal obstruction. We should not forget, then, that fog and particularly dense smoke fog may entirely extinguish those rays of the sun which exert not only a germicidal action, but which also possess a tonic, vitalizing quality, viz., the short wave lengths.