Control of pollutants from mobile sources has been a persistent problem for well over 100 years. While today’s focus is primarily on emissions from the internal combustion engine, before 1960, clean air crusaders considered the coal-burning steam locomotive the mobile source most affecting urban air quality. The problem of controlling railroad smoke included many of the same elements involved in today’s regulation of emissions from the internal combustion engine: questions of technology and fuel, issues of personnel training, and policy regarding emissions standards and enforcement. Regulations, however, were primarily municipal rather than state or national.
Like today, fuel was a critical element. American railroads had originally burned wood, but as wood supplies diminished, they substituted coal. Initially, railroads used cleanburning anthracite, but as the tracks moved further west and away from the anthracite mines they adopted the more widely distributed and cheaper high-volatile bituminous coal. By 1880, coal, mostly bituminous, accounted for more than 90% of locomotive fuel.
Next to labor, fuel constituted the most expensive single material purchased by the railroads. When fuel costs were high, railroads paid special attention to factors that would help them achieve the maximum amount of transportation at minimum fuel expense. Coal was also important to the railroads because it constituted their largest single item of revenue tonnage—approximately 20% of freight cars hauled. Burning fuel efficiently and retaining the coal trade were critical components of the railroad business strategy. Railroad locomotives generated copious amounts of dense smoke and cinders because they primarily burned a dirty fuel—bituminous coal—and because they were inefficient fuel consumers.
Furthermore, locomotive smoke, as compared to smoke from other industrial sources, was particularly offensive because moving trains often dispersed it at a relatively low height over a wide area. Railroads were motivated to control locomotive smoke by both internal and external factors. Internal factors included a drive for increased efficiency and economy of operation. In addition, railway managers were especially concerned about the dense smoke emitted by locomotives pulling passenger cars since competition for passenger traffic was intense. External elements included pressure from the enforcement of municipal smoke control regulations. These regulations often forced the railroads to undertake smoke control measures that they would not have voluntarily adopted because they added to the costs of operation.