Many efforts have been made by American cities to mitigate the smoke nuisance. In addition to causing great economic losses by injuring merchandise, defacing buildings, ruining contents of homes and by the waste of the fuel value, smoke is probably a predisposing cause of pulmonary diseases and by obscuring the sun's ultra-violet rays is undoubtedly prejudicial to health. Pre vious to 1917 many American cities had smoke regulations which, however, were not widely observed, and during the World War, regulations were held in abeyance. With the return of normal conditions health organizations met with considerable interested opposition, public apathy and often official indifference. In 1924 more than so American cities had smoke regulations. The admin istration of these was variously under the jurisdiction of health, boiler inspection, building departments or departments of public safety. New York city, Chicago, Baltimore, Philadelphia, Louis ville, Denver and Columbus, 0., were cities in this class. Mil waukee, Cincinnati, Salt Lake City, St. Louis and Harrisburg, Pa., had independent bureaux or departments for the purpose.
A smoke advisory committee, composed of engineers co-oper ating with the New York city department of health, reported in Dec. 1927, the results of a survey. The report declared that inas much as the supply of Pennsylvania anthracite was rapidly becom ing exhausted, smoke-producing coal would necessarily become New York's main future supply. The report affirmed, however,
that smoke from soft coal could be reduced at least 5o% by suitable coal-burning appliances and careful supervision. The in creasing substitution of fuel-oil and gas for coal promised bene ficial results. By 1921 fuel-oil had replaced coal in the sugar, glass and certain other industries. This movement went on both in the east where ,anthracite was used and in the west where bitu minous coal is the chief domestic fuel. Many of these were in stalled in heaters formerly using coal. The railways, long re sponsible for a great part' of the smoke in urban districts, used 70,00o,000bbl. of fuel-oil in 1925.