June 9, 1916. THE COLLIERY GUARDIAN. 1101 THE HEALTH OF OLD COLLIERS.* By J. S. Haldane, M.D., F.R.S. . Every 10 years there is published a supplement to the Registrar-General’s reports, in which the annual mortality in different occupations is set out and dis- cussed generally, so that the relative healthiness of these occupations can be definitely gauged. . It was shown in the last supplement, in connection wich the census of 1901, that the general death rate among colliers was considerably lower than in the great majority of occupations. But there is an exception to this in the case of colliers above the age of 55. These points are shown in Table I., in which are also incor- porated the earliest available official figures—those given in evidence before the Royal Commission on Mines that reported in 1864. Table I.—Death-rates per 1,000 living at each Age Period. 1849-1853. 1900-1902. Age <— ■ \ Occupied Occupied period. All Coal and and males. * miners.! retired retired coal males.* miners.* 1 -25 ... ... 8T ... ... 14’5 ... .... 3’5 . 3’8 25-35 ... ... 10T ... ... 14’5 .. ... 6 3 . 5T 35-45 ... ... 12’7 ... ... 17’2 ... ... 10’9 ... 7'6 45-55 ... ... 18’9 ... ... 26’3 .. ... 18’7 . 147 55-65 ... ... 31'8 ... ... 44’0 ... 35’6 .. .. 38’0 Over 65 ... ■— — ... 106’0 ... 128’6 * England and Wales. + Mean for Staffordshire, South Wales, and Northumberland and Durham. These figures are further analysed in Tables II., III., and IV. Table II.—Death-rates from Accident per 1,000 living at each Age Period. 1849-1853. 1900-1902. Age 'i r Occupied O. cupied period. . All ■ Coal and and males. miners. retired retired coal m ales. miners. 15-25 ... ... 0’9 ... .... 5’7 .. .... 0’5 1’2 25-35 ... ... 1’0 ... .... 5’3 .. .... 0’6 1’2 35-45 ... ... 1’15 ... ... 6’2 .. .... 0’8 . 1’6 45-55 ... ... 1’4 ... .... 6’9 .. .... 10 2-1 55-65 ... 1’6 ... .... 5’9 .. .... 1’4 2’7 Over 65 .... — — .... 21 3’3 Table III.—Death-rates from Lung Disease per l,0<0 living at each Age Period. 1849-1853. A . _ . 1900-1902. Age ( r Occupied Occupied period. All Coal and and males. . miners. retired retired coal males. miners. 15-25 .... .. 3’6 3’5 ... ... 1’4 10 25-35 .... .. 4’8 3’1 ... ... 2’9 . 1’6 35-45 .... .. 5’3 3’7 ... ... 4 6 . 2’4 45-55 .... .. 6’8 7 1 ... ... 6’6 4’9 55 65 .... .. 9'6 163 ... ... 10’0 . ..... 12’5 Over 65 .... — — .. 22’2 . 36’1 Table IV.—Death-rates from oiher Causes than Accident or Lung Disease per Age Period. 1849-1853. 1,000 LIVING AT EACH 1900-1902. Age period. (— All Coal Occupied and Occupied and males. miners. retired retired coal 15-25 .... .. 3’6 ... .... 5'3 .. .. males. .. 1’6 . miners. .. .. 1’8 25-25 .... ... 4’3 .. .... 6'1 .. 2’8 . 2’3 35-45 .... ... 6’3 ... .... 7’3 .. 5’5 . 3’6 45-55 .... .. 10’7 .. .... 12’3 .. iri 7'7 55-65 .... .. 20’6 .. .... 21'8 .. 24’2 22'8 Over 65 .... — — . 81’7 . 89’2 It will be seen from Table I. that whereas about 1851 the death rates at all ages wrere considerably higher among colliers than among the general population, the converse was the case in 1901. About 1881 the rates had become about equal. In the 50 years from 1851 the death rate fell greatly among the general population; but the fall is far more striking among colliers than in other occupations. Table II. shows the enormous fall in the accident death rate among colliers. Table III. brings out the very significant fact that up to the age of about 50 the death rate from lung diseases is much lower among colliers than in the average population, and was so even in 1851; whereas above 50 the converse is the case. The purpose of this paper is to concentrate attention on the reason for the continued high death rate among old colliers. According to the census of 1901, out of a total of 609,000 men employed as colliers, 35,800 (or 5-9 per cent.) were aged 55 to, 65, and 10,000 (or 1-6 per cent.) above 65. It is thus only to a small propor- tion of actual colliers that the higher death rate applies. Nevertheless, this higher death rate must, if correct, be an index of much invalidity—of the premature wearing out of many men. Hence the matter is one of serious concern. As coal mining is a strenuous occupation, it is natural that colliers should retire or go into some other occupa- tion when they reach a certain age. From the census returns for 1901, it appears that for 1,000 men living at the age of 45 to 55, there were -650 at the age of 55 to 65, and 473 at over 65. Among colliers, on the other hand, for 1,000 employed at 45 to 55, there were only 479 returned as employed at 55 to 65, and 134 at over 65. If those returned as retired colliers be added, the numbers are still only 506 at 55 to 65, and 212 at over 65. It seems, therefore, that a large proportion of colliers do take to other occupations, or for some other reason were not returned as colliers. Now, the numbers of occupied and retired men in each occupation are taken from the census returns. On the other hand, the deaths, and the present or previous occupation to which each death is credited, are returned * From a paper read before the Institution of Mining Engineers. by the local registrars. If, therefore, the census and the legistrars’ returns are not both complete, the death rates calculated from them will be more or less inaccurate. The last decennial supplement gives the death rate for all males over 65 as 94-6 per 1,000, for all occupied males as 88-4, and for occupied and retired males as 106-2. From the figures given, it follows that the calculated death rate for retired males is 148-0. But the total of occupied and retired males above 65 is only 86 per cent, of all males above 65, and the missing 14 per cent, belong mainly, so far as can be judged, to the retired class. The “ retired ” and “ missing ” class together have a death rate of 104-2, and this is probably about the real death rate of the retired class. There can be no doubt that the returns of previous and present occupations of old persons by the registrars were much more complete than the census returns, so that the total of old persons to which the corresponding deaths were credited was too small, and the death rate consequently too high. - ' This source of error appears to have told with special heaviness on the death rates calculated for colliers above the age of 55, since so large a proportion of old colliers retire from their work as colliers, but may still come to be entered in either registrars’ or census returns as either “ occupied,” or simply unoccupied.” In general, the “ retired ” class in each occupation has a much higher calculated death rate in each occupation than the “ occupied ” class. Most of the excess is only apparent, as just explained; but part is certainly real, and due to the facts that the “ retired ” class are older o i an average, and that retirement has often been due to some ailment which ultimately proved fatal. In the case of colliers over 65, however, the calculated death rate (109 6) is much lower among the “ retired ” than among the “ occupied ” (139-8). The existence of this strange anomaly leaves little doubt as to the incorrect- ness of the death rates for occupied and retired colliers as given in the last decennial supplement. By the courtesy of the Registrar-General and of Dr. Stevenson, Superintendent of Statistics, the writer is enabled to refer to a few of the figures belonging to the next decennial supplement, which is delayed owing to the staff of the department being largely engaged in war work. These figures refer to the number and calculated death rates of occupied and retired colliers over 65 in the years 1910-12. It appears that in the census of 1911, 29,549 men were registered in the census as occupied and retired colliers, whereas only 15,879 were so registered in the 1901 census. It would be absurd to suppose that the number of old colliers had nearly doubled in 10 years, so that the 1901 figures are clearly shown to have been wrong. The calculated death rate among occupied and retired colliers in 1910-12 was 105-5, instead of the high figure of 128-6 for 1900-02. The new figure is slightly lower than the corresponding one for all occupied and retired males in 1900-02, and removes once for all the painful impression produced by the existing published figures. Whether, and, if so, to what extent, the true existing death rate of occupied and retired colliers above the age of 55 is higher than in other occupations, must remain in doubt for the present. The writer thinks, however, that it has been higher in the past; for, even if the older calculated death rates are discarded, another method of judging is left. Different occupations leave their marks on men, and these marks are shown in ten- dencies to die more readily from certain affections. Now, if the proportions due to particular causes among the total deaths registered among occupied and retired colliers above the age of 55 be analysed, there appears to be a marked excess of deaths from bronchitis. This fact, as well as the great difference between different occupations with regard to the mortality from bronchitis in old age is shown by the fact that, whereas in the returns for 1900-02 the deaths from bronchitis among all occupied and retired males over 65 in England and Wales were 13-2 per- cent. of total deaths, and the calculated death rate from bronchitis per' 1,000 was 14-1, the figures for clergymen were 6-5 and 5-3 respectively, and for coal miners 19-6 and 25-2 respectively. For the period 1910-12 the corresponding figures for coal miners were 17-6 and 18-4 per 1,000 deaths. These figures indicate a rough general relationship between mortality from bronchitis in old age and work involving considerable physical exertion. Turning to the bronchitis mortality among old colliers, as indicated by the figures of successive decennial supplements, Table V. shows the figures since data on the subject were first published, and indicates very clearly that bronchitis has diminished greatly among old colliers since 1890, although it is still in excess. TableV.— Coal Miners above 65 in England and Wales. 1890-92. 1900-02. 1910-12. Deaths from bronchitis as per- centage of total deaths— Occupied 26'0 ... . 20’0 . .. 18'1 Occupied and retired — . 19’6 . 17'6 Calculated death-rate from bronchitis per 1,000— Occupied 38'1 .. . 28’0 . Occupied and retired... — . 25’2 . 18'4 Total calculated death-rate per 1,000— Occupied 146’4 .. . 139’8 . Occupied and retired ■— . 128'6 . .. 105'5 The excessive rate in the first period was probably due to a considerable extent to the prevalence of dangerous influenza at that time; but the relative excess among old colliers is none the less significant. A connection has already been pointed out between excessive physical exertion and a tendency to die of bronchitis in" old age. Now, hard physical exertion is accompanied by. hard breathing, and constant over- distension of the lungs tends to. bring about what is known as “ emphysema ”—a condition in which the delicate walls of the air cavities of the lungs are more or less ruptured. With emphysema existing, bronchitis becomes more dangerous; and it would seem that the increased tendency to. death from bronchitis in occupa- tions involving excessive exertion is due to the emphysema induced by overstretching of the lungs during that exertion. Improvement in ventilation seems the most probable cause of the great diminution of bronchitis among aged colliers. Apparently, it was common 40 or 50 years ago for coal miners to be working in air containing so much blackdamp that lamps or candles burned dimly. In such air there is usually 2 or 3 per cent, of carbon dioxide, which has an enormous effect in increasing the breathing during muscular exertion. The breathing is exactly regulated so. as to keep an average of about 5-6 per cent, of carbon dioxide in the air filling the air cavities of the lungs; and with 3 per cent, of this gas in the air a man breathes twice as much air, so ns to keep the percentage right in the' lungs. A man doing moderate muscular work in pure air would breathe about five or six times as much air as during rest. In air containing 3 per cent, of’carbon dioxide, he would be breathing .10 or 12 times as much air as during rest, and his breathing would be taxed to. the utmost. He would thus be much more liable to contract emphysema. . The better ventilation of coal mines is largely a conse- quence of the greater amount of firedamp and greater heat met with as mines have become deeper, and the wiiter is inclined to think that both the firedamp and the heat have hitherto resulted indirectly in great improvement to the health of miners. Where there is plenty of firedamp there is usually also plenty of fresh and dry air, and no harmful excess of carbon dioxide. The proportion of deaths from bronchitis -among old miners was higher in Staffordshire in 1890-92 and 1900-02 than in any of the other coal fields; and Stafford- shire mines are, on the whole, exceptionally subject to blackdamp. The excess in bronchitis among old coal miners has been attributed to the breathing of dust, and the writer was previously inclined to agree with this theory. But it is very difficult to. see why, if dust is the cause, there has been so great a diminution in the bronchitis mor- tality in recent years. Coal mines have, on the whole, become drier and more dusty with increasing depth and better ventilation; and, if dust were the cause, one would have expected the bronchitis to. increase, whereas it has greatly diminished. It is certainly the case that -an excess in mortality from bronchitis is associated with the breathing of harmful dust. But this excess is accompanied by a far greater excess in mortality from phthisis, and begins comparatively early in life, unlike the bronchitis mortality of colliers. The experiments carried out by Prof. J. M. Beattie, and more recently by Dr. A. Mavrogordato, show that both coal dust and shale dust are relatively harmless, being readily eliminated by the agency of living cells, which collect the dust and then wander out with it into the bronchial tubes, whence it is swept upwards by the action of the ciliated epithelium which lines the air passages. This ready elimination does not occur with other dusts known by human experience to be dangerous and liable, in particular, to. predispose the persons con- cerned to phthisis. In short, coal dust and shale dust, when introduced into- the lungs, summon up the activities of thousands of tiny housemaids, who collect and gradually make away with the dust. If the quan- tity of dust inhaled is not too great, therefore, the clean- ing up process keeps pace with the introduction of the dust, and no harm results. Colliers suffer very little from phthisis, the last decennial supplement showing the death rates from phthisis per 1,000 for England and Wales, 1900-02, being in the case of occupied and retired coal miners 0-7 (age period 15-25); 1-0 (25-35); 1-1 (35-45); 1-5 (45-55); 2-0 (55-65); whereas the figures for tin miners, who are exposed to dangerous dust, are much higher, e.g., 16-1 per 1,000-between 45 and 55. Coal dust certainly does not kill germs; but it has come to be regarded by medical men as a preventive of phthisis. It seems probable, therefore, that the “ housemaid ” cells which clear out the dust particles, clear out at the same time other “ foreign bodies,” such as tubercle bacilli. If this is so, coal dust in modera- tion is, on the whole, an advantage to the safety of colliers. In any case, the evidence does not now bear out the theory that the excessive bronchitis of old colliers is due to dust inhalation. The writer does not think that there is any evidence in favour of the idea that the excessive bronchitis in old colliers is due to exposure to changes of temperature. Miners do not appear to take harm in this way; and in other occupations associated with exposure to extremes of weather, there is no excess of bronchitis among either young or old. The practical conclusions to be drawn from this paper are :—(1) That good ventilation is of considerable importance to the health and continued working efficiency of miners, as well as to their safety from accidents; and (2) that there is no real statistical evidence of harm resulting from the inhalation of coal dust or shale dust in the quantities ordinarily breathed by miners, and a strong presumption that the dust they breathe protects them against serious dangers. It is satisfactory to find that the excessive death rate among old colliers is to a large extent only apparent, and that the real excess of bronchitis from which they have suffered has greatly diminished. • Grimsby Coal Exports.—The following is the official return of the quantities of coal exported from Grimsby during the week ending June 2 :—To Dieppe, 202 tons ; Dunkirk, 891; Gothenburg, 700; Flaugesund, 105; Savona, 2,702; and Treport, 167—total, 4,767 tons, compared with 3,885 tons in the corresponding week of.last year...