May 2017

A Brief Summary of The Silent Epidemic: Coal and the Hidden Threat to Health

All the following information is cited from Lockwood, Alan H. The silent epidemic: coal and the hidden threat to health. Mit Press, 2012. Not opinions of Ruoding Shi

  1. Introduction

About 45% of the energy used to generate electricity in the U.S. comes from burning coal, and 28.9% world coal reserves are in U.S. One third coal was mined in Appalachia. Recently, researchers observe increasing incidence rates of coal-related diseases, such as black lung disease, which may be caused by relaxation of regulatory activity due to lobby effects of coal-based companies.

  1. Mechanism of coal effect on health (mainly through air pollution)

It is difficult to link a coal activity to a health effect in question, but we can define the proportion of the pollutant that is attributed to coal activities, such as oxides of sulfur, nitrogen and particulate. This book focuses on burning coal. Usually, high rated coal has a low-ash and low-sulfur content. As for miners, working in a big coal mine is better for their health than working in a small coal mine, and surface mining is better than underground mining for miners’ health. For example, black lung diseases are more prevalent among underground miners than surface miners. For general population, the most influential coal effect seems to be burning coal, which produces huge amount of coal ash containing harmful materials and chemicals such as

  • Particulate: PM 2.5 and PM 10: especially on children and outdoor lovers. Inhaled particulate causes inflammatory response, increased free radical and oxidative stress
  • Oxides of sulfur: burning coal is a leading source
  • Oxides of Nitrogen
  • Mercury: can be found in fish. Bad for brain.


The following are coal-related respiratory diseases

  • Asthma: air pollution as a trigger of asthma, such as ozone
  • COPD: narrowing airway is permanent
  • pulmonary inflammation
  • lung cancer
  • Black lung disease: diagnosed by chest X-ray, working  history and elimination of other illness
  1. Understanding coal mining

Generally, there are two types of mining techniques:

1) . surface mines include

  • Strip mines: huge pieces of earth-moving to remove the soil and rock covers the bed of coal
  • Open-pit mines: create an enormous hole in the ground and make it difficult to reclaim the land
  • Mountain-top-removal valley-fill mines: the top of a mountain is removed and dumped into an adjacent valley, the consequence is that the valleys and their ecosystems are destroyed and water supply may be damaged.


2) Underground mining techniques include

  • long-wall mining: Once the shaft reaches the seam of coal, a rotating drum equipped with teeth moves back and forth to loosening the coal from the seam. Typically, this is highly mechanized.


All mines may damage ecosystem. Mining exposes large surface of rock and may leach dissolved mineral and heavy metals into the water supply. Large amount of methane and coal dust are released when coal is mined, as well as high sulfate concentrations in coal mining areas.

  1. Coal washing

This step separates the coal from dirt and rock based on differences in their weights. However, disposal of the resulting waste or slurry is substantial challenge. Most coal slurry is stored by impoundment behind dams or injection into abandoned mines, so there is a concern that chemicals will leach into the groundwater, which may cause kidney diseases.


  1. Policy implications

1) Why it matters?

Health care cost are rising faster than any other segment of the economy. So we need to know and define something about the population that is potentially affected by coal industry, and do cost and benefit analysis.

2) Policies that can be helpful

  • Clean Air Act and other EPA regulations
  • Federal Coal Mine Health and Safety Act of 1969: This act established limits on the exposure to dust from coal mines and established a chest X ray screening program for underground miners. However, researchers found recent relaxation of regulatory activity due to lobbying effects, especially in small coal mines.
  • Air Quality Act of 1967

3) Increase the efficiency of energy use

4) Give the public an opportunity to be informed and comment on proposal rules

5) Role of physicians: be aware and prevent diseases caused by environmental pollutions and actively participate in community health issues.

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