Case Study

Black Lung Incidence Study for the U.S. Department of Labor Chief Evaluation Office

Challenge: The U.S. Department of Labor’s Chief Evaluation Office (CEO) partnered with the Mine Safety and Health Administration (MSHA) to examine the rate of black lung disease across the United States. Specifically, CEO and MSHA sought to understand (1) whether black lung cases and deaths are more prevalent in the Navajo Nation or Appalachia than other parts of the United States, (2) how black lung incidence compares between current, former, and non-coal mining communities, and (3) how residential coal burning correlates with black lung cases and deaths.

Solution: Summit used a mixed-methods approach that incorporated both qualitative and quantitative data to answer these questions. First, we conducted a literature review to explore black lung disease diagnosis and measurement to determine a definition of black lung disease. Because black lung disease is an umbrella term that can be used to refer to a wide variety of diseases associated with respirable coal mine dust, Summit identified a list of relevant medical diagnostic codes from the International Classification of Diseases system to define black lung for use in this study. Additionally, we reviewed and analyzed literature focused on coal mining, residential coal burning, and black lung incidence in Appalachian populations and the Navajo Nation.

Insights from the literature review helped inform the quantitative portion of this study. Summit conducted descriptive and inferential statistical analysis of key data points from aggregated public health data to identify black lung incidence (both living cases and deaths) across time for the populations of interest. We also used this analysis to determine whether the causes for higher rates of black lung disease can be disaggregated. Key sources of public health data included the U.S. Centers for Disease Control (CDC) Wide-ranging ONline Data for Epidemiologic Research database and the CDC Enhanced Coal Workers’ Health Surveillance Program database. Other key sources of data included the U.S. Census County Business Patterns datasets and the MSHA Mines dataset, which were used to understand the coal industry’s influence across the United States.

Result: Key takeaways from Summit’s analysis include:

    • The prevalence of coal workers’ pneumoconiosis, one of the diseases that defines black lung disease, has been increasing in the United States since the 1990s. Even with this rise, experts suspect black lung cases are undercounted due to a variety of factors, including low participation rates in free radiograph screenings offered by the CDC.
    • There are averages of 4.34 cumulative cases (in the period 1970–2014) and 3.44 cumulative deaths (in the period 1999–2020) attributable to black lung disease per county across the United States.
    • Per 1,000 United States residents, there are 0.11 black lung cases and 0.04 black lung deaths.
    • Appalachia has significantly more black lung cases and deaths than the rest of the United States: statistics rise to averages of 28.79 cumulative cases and 10.88 cumulative deaths (not subject to population size).
    • Hypothesis testing between the Navajo Nation and the rest of the United States proved inconclusive due to low counts of cases and deaths in the respective collection periods, which may be a function of underreporting black lung disease in the Navajo Nation.
    • When examining current, former, and non-coal mining communities, Summit found that black lung disease is most prevalent in current coal mining communities.
    • There is a correlation between residential coal use and black lung cases and deaths, though this does not imply a causal relationship.

Summit identified two potential next steps to help future researchers understand the impact of coal on health. First, because the literature review findings suggest that the public health burden of coal is high in the Navajo Nation despite a lack of data, we recommended additional research to address the lack of public health data available for analysis in the Navajo Nation. Second, we recommended a follow-on study with similar research questions that focus specifically on silicosis (a lung disease associated with exposure to silica dust) in response to a recently announced proposed rule change to address health hazards from silica dust exposure. Read Summit’s literature review, final report, and Navajo Nation research brief on the Department of Labor’s website.