The deleterious effects on the human system from inhalation of smoke-polluted air, which contains not only acrid and irritating solids, but a certain amount of deadly poisons, should be obvious from a consideration of the comparatively great density of the impurities in the atmosphere of industrial centers. The weight of the solid matter in the soot-laden air at Leeds, England, has been found to be 1.2 mg. per 100 cu. ft. of air, or 200 lbs. per sq. mi. (300 ft. high.) The soot-fall per square mile per year has amounted to 220 tons in Leeds, 820 tons in Glasgow and 259 tons in London. Moreover, by means of the dust counter the number of dust particles in the air at Leeds has been found to vary from 530,000 to 3,736,000 per cu. inch. In manufacturing cities the number of dust particles often exceeds 300,000 per cu. cm. even in fine weather, as compared with a few hundred in the country (Aitken, 4). A large percentage of these particles consists of the soot from factory, locomotive and domestic fires. Not only are these conditions, bad as they are, aggravated during foggy weather but on moderately foggy days the quantity of solid organic impurities may be increased 700% as compared with fine weather (Russell). During grimy, opaque fogs, the conditions are still worse. That the constant inhalation of poison-laden air, largely made up of the soot particles which abound in manufacturing cities, diminishes the potential reserve, the productive efficiency and the bodily well-being of our city dwellers by causing specific diseases, has been abundantly shown by various studies. The mortality from acute pulmonary diseases, especially in children and old people, has increased, and the course of pulmonary tuberculosis has been accelerated in Germany as the country has become more industrial. The increase in non-tubercular lung mortality has amounted to 30% in the smoky town of Waldenburg compared with the nearby textile town of Wusterwaltersdorf (Ascher, 16). The death rate per 10,000 for the same diseases is 30.6 in the non-smoky city of Hamm as compared with 57.4 in the smoky city of Gelserkirchen. In all German towns with a population of over 15,000 the death rate is 24.0, while in the smoky industrial centers of similar size in Rhenish Westphalia it is 34.0, and in the industrial districts in upper Silesia it is 36.0 (Ascher, 4); in rural districts in England it is 17.5 compared with 26.5 in urban industrial districts(4). During the anthracite strike in this country there was reported an increase of suspected tubercular cases. In Rochester there was observed an increase of pulmonary affections with the increase of the smoke nuisance between 1895-1904. In Pittsburgh a recent investigation by Dr. W. C. White shows that pneumonia increases with the density of atmospheric smoke, irrespective of the density of population or of poverty. The increase is as marked in the well-to-do as in the poorer sections with relatively the same smoke density.