I’m shocked, shocked to find so many U.S. coal miners with black lung disease

I felt a little like Claude Rains (as Capt. Louis Renault) in the film Casablanca. He’s the actor with the famous line “I’m shocked, shocked to find that gambling is going on here.” On Sunday my neighbor asked me: “What do you think about all those coal miners with black lung?”

“Shocked, shocked,” I was tempted to say, but I’m not the least bit shocked.

My neighbor was referring to the latest story by NPR’s Howard Berkes about nearly 2,000 cases of progressive massive pulmonary fibrosis (PMF) diagnosed in the last six years among Appalachian coal miners. Two thousand cases is a hefty number, especially given the federal government’s official count which is 1/20th that amount.

Following earlier reporting by Berkes in December 2016, the CDC’s National Institute for Occupational Safety and Health (NIOSH) began its own special investigation of the prevalence of coal workers’ pneumoconiosis in certain Appalachian communities. Last month, NIOSH epidemiologist Scott Laney told a National Academy of Sciences’ panel:

“We are in the midst of an epidemic of black lung disease in Central Appalachia that is historically unparalleled.”

Preliminary data from NIOSH indicates that many of the miners being diagnosed with black lung began their mining careers after 1986. Their median age is 60.

Am I shocked about the epidemic? I’m sorry to say that I’m not. Here’s why:

#1:  Mine operators were allowed to expose miners to concentrations of respirable coal dust and silica that were known to be too high and would cause lung disease.

#2:  Mine operators cheated when air samples were collected to make dust levels appear lower than they were.

#3:  Inspectors could not sanction mines for not controlling dust because of an arcane policy of averaging air sampling results.

#4:  The mining industry used legal maneuvers and influence with lawmakers to obstruct policies that would have provided greater protections for miners.

#5:  Many miners delay getting diagnostic tests for lung disease until they retire or are laid off indefinitely.

In this post, I’ll explain #1 and #2. In a post tomorrow, I’ll elaborate on #3, #4, and #5.

Not shocked #1: Dust levels too high.

  • At least as early as 1995, there was sufficient evidence to illustrate that the 2.0 mg/m3 permissible exposure limit for respirable coal dust over a work shift was too high. Coal miners were developing respiratory diseases as a result. The key collection of evidence was assembled by NIOSH and published in 1995 entitled “Criteria for a Recommended Standard: Occupational Exposure to Respirable Coal Mine Dust.” NIOSH recommended that exposure to respirable coal mine dust be limited to 1.0 mg/m3 as a time weighted average concentration for up to 10 hours per day during a 40-hour work week.
  • NIOSH also recommended that the permissible exposure limit not be adjusted upward to account for measurement uncertainty. MSHA has the practice of making a generous adjustment to dust sample results to give mine operators 95% confidence in the accuracy of the air sample. In practice, although the permissible exposure limit was 2.0 mg/m3, MSHA would not issue a citation for exceeding the limit unless the concentration of respirable coal dust was equal to or greater than 2.33 mg/m3. (Jim Weeks explains it well in a 2006 paper in the American Journal of Industrial Medicine.)
  • An assessment prepared by MSHA in 2010 estimated the risk for coal miners of developing lung disease at the existing 2.0 mg/m3 exposure limit. The estimates were based on an assumption of a 45 years of working in coal mines. Those diseases included coal workers’ pneumoconiosis, COPD, and emphysema. MSHA estimated disease risk for different coal mining occupations and the type of coal being mined. I adapted the following from data in MSHA’s quantitative risk assessment:

Much of the underlying data for MSHA’s 2013 risk assessment is from the same seminal studies used by NIOSH for its recommendation in 1995.  Should the epidemic of black lung be a surprise when these estimates indicate that 1 in 6, or 1 in 5, or 1 in 4 coal miners would develop serious respiratory diseases?

  • A preliminary risk assessment by MSHA in 2010 provided estimates of disease risk at a 1.0 mg/m3 exposure limit. The following is adapted from that document. It shows a significant reduction in disease risk when the permissible exposure limit is cut in half:

  • MSHA implemented a new regulation in August 2016 which reduced the permissible exposure limit for coal mine dust. The agency did not adopt the limit of 1.0 mg/m3 which NIOSH recommended in 1995. It adopted instead a 1.5 mg/m3 limit.
  • MSHA should have adopted a 1.0 mg/m3 (or lower exposure limit.) The best available data showed it was feasible for the coal industry to comply with a limit below 1.5 mg/m3.
  • Also contrary to NIOSH’s 1995 recommendation, MSHA is continuing to make a generous adjustment to dust sample results to give mine operators 95% confidence in their accuracy. For the new 1.5 mg/m3 exposure limit, inspectors won’t issue a citation unless the value exceeds 1.70 or 1.79, depending on the air sampling device used.
  • Most coal miners are exposed simultaneously to two respiratory toxins that cause fibrosis: coal dust and silica dust (i.e., quartz.) Silica is suspected to be a more potent agent. MSHA enforces an exposure limit for silica that dates back to 1968. It is a value set by the American Conference of Governmental Industrial Hygienists and is equivalent to 100 ug/m3. In 1974, NIOSH recommended to MSHA and OSHA that their permissible exposure limits for respirable silica be reduced to 50 ug/m3. OSHA recently adopted the 50 ug/m3 limit, but MSHA has postponed doing so.

Not shocked #2: Too many mine operators cheat.

  • The purpose of taking measurements of air contaminants in a workplace setting should be to capture information about typical working conditions. That can be difficult to pull off especially if someone is not interested in the truth. Slowing down production, changing the normal ventilation pattern, tampering with the sampling device, etc., etc. can easily skew the results. Disguising the typical conditions allows employers to avoid making improvements to reduce exposure to contaminants. In U.S. coal mines, many companies were masters of this kind of deception.
  • Around about 1990, MSHA caught coal operators in a massive cheating scandal. I can’t get my hands on the data at the moment, but the New York Times reported on the scandal, saying it involved 40 percent of the nation’s coal mines. Labor Secretary Lynn Martin caught a lot of slack from the industry for suggesting the industry was addicted to cheating. She said:

“It seems almost an addiction to cheat at some mines.”

  • In 1998, the Louisville Courier-Journal’s Gardiner Harris (now at New York Times) investigated the ways in which mine operators deceived inspectors and gamed the dust sampling system. What Harris wrote was not news in coal mining towns, but he got it down on paper for the series, “The Dust They Breathe”:

“Miners said they used to simply turn the dust pumps off when an inspector turned his back. In 1993, MSHA changed to pumps that couldn’t be turned off. To thwart the new pumps, the miners said they stick cotton or cigarette filters over the intake hole or put the hole under their clothing.”

  • Coal miners were involved in the cheating for a simple reason: keeping their jobs. I can hear the one-sided conversation from the boss: “Won’t hide the sampling pump in your dinner bucket? Don’t bother showing up for work tomorrow.”

Shocked, shocked?

Schemes to prevent inspectors from doing their jobs, plus permissible exposure limits for respirable dust that cause disease, are two ingredients in the black lung epidemic. Tomorrow I’ll elaborate on three more ingredients: an arcane averaging policy that diluted the results dust samples; the mining industry’s legal maneuvers to obstruct protections for coal miners; and the workers’ decisions to delay having diagnostic tests for lung disease.




  1. #1 Mentifex (Arthur T. Murray)
    Seattle WA USA
    July 6, 2017

    Round up the usual suspects. But actually, even more than “We’ll always have Paris,” my favorite line is, “Of all the gin joints in all the towns in all the world, she walks into mine.”