In the classic story that exemplifies the public health approach to disease prevention, John Snow removed the handle of the Broad Street pump in London to halt a cholera epidemic. Snow knew neither the agent of the disease nor its mechanism, but he acted after making reasoned conclusions drawn from systematic observations of the distribution of the disease. In his carefully researched and exhaustively referenced book, Black Lung: Anatomy of a Public Health Disaster, historian Alan Derickson asks why the "pump handle" was not removed -- why dust was not controlled -- when so much was known for so long about the harmful effects of excessive dust exposure among coal miners. Black Lung is a cautionary tale, warning of the consequences of allowing economic and political considerations to control public health decisions. Engaging, well-organized, and fast-paced, the book guides the reader through a century of change in the mining, scientific, and regulatory communities. Beginning in the mid-19th century, first in the United Kingdom and then in the United States, lung diseases, commonly called "miner's asthma" or "miner's consumption" and medically labeled "anthracosis," were observed in coal miners. Sick miners had progressive dyspnea, chest discomfort, and cough, sometimes dramatically accompanied by the expectoration of copious quantities of black, inky sputum. Medical textbooks, including Osler's classic Principles and Practice of Medicine (New York: D. Appleton), first published in 1892, described a lung disease observed in miners and caused by exposure to dust. But early in the 20th century, according to Derickson, conventional scientific wisdom seemed to have undergone a critical transformation. The observation in the United Kingdom that rates of tuberculosis were lower among miners than among laborers in urban areas led to the assertion in the United States that inhalation of coal-mine dust had a beneficial effect and that dust-induced pulmonary fibrosis hardened the lungs against infection. Derickson argues that as concern about the devastating effects of silica dust became widespread, a "reductionist" approach equated all dust-related hazards with silica, thereby deflecting attention from the independent risk posed by coal-mine dust. From this arose the belief that in the absence of silica, coal-mine dust is benign -- discoloring the lungs but not causing impairment. The belief that exposure to coal-mine dust had only benign effects could have been challenged by scientific inquiry. In fact, Derickson cites reports produced for the U.S. Department of Labor and the results of field investigations conducted by the U.S. Public Health Service indicating that miners had high death rates; diminished longevity and reduced pulmonary function as compared with other manual laborers; and a high rate of absence from work due to lung conditions. These reports, however, were not widely distributed, because access to workplaces was granted to government agencies in return for agreements to restrict communication of the results of investigations. For this reason, scientific evidence of the hazards of coal-dust exposure did not prompt requirements for improved ventilation or other preventive actions. Derickson also explores how efforts to minimize compensation to miners with lung disease may have affected the willingness of official bodies to recognize the connection between work and disease. Unfortunately, Derickson fails to describe accurately the current concept of diversity in the lung diseases of coal miners. Exposure to coal-mine dust causes not only coal workers' pneumoconiosis but also chronic bronchitis and emphysema and, depending on the quartz content of the inhaled dust, silicosis. A clearer presentation of this complex of diseases would have provided readers with context for understanding the evolution of the varied beliefs and approaches to lung diseases among coal miners. Compensating for this weakness is an important strength of the book: Derickson's description of the social and economic consequences of lung disease in the coal fields. Young boys began work as slate pickers, cleaning and sorting coal for entry-level wages in densely dusty environments. As the children grew older and stronger, they moved progressively up the job and pay ladders, helping to transport, load, and ultimately mine coal. When injury or disease incapacitated miners, these men, having no social safety net and minimal employment alternatives, climbed back down the job ladder, sometimes ending their careers in the breakers, cleaning coal as they did in their youth, still for entry-level wages, only this time in failing health. The ultimate lesson of Derickson's book is one worth heeding: to prevent public health disasters, prudent action may be necessary, even in the face of scientific uncertainty.