After a long period of declining rates, the prevalence of coal workers’ pneumoconiosis (CWP) is on the rise, and coal miners are developing CWP at relatively young ages.

Those are among the conclusions of a report on the health effects of coal mining just released by the National Institute for Occupational Safety and Health (NIOSH).

The“Current Intelligence Bulletin 64: Coal Mine Dust Exposures and Associated Health Outcomes”updates the information on coal mine dust exposures and associated health effects from 1995 to the present, focusing on whether or not whether recommendations from a 1995 report needed to be updated or supplemented in light of recent findings.

NIOSH researchers found that the increase in CWP –which has been linked to exposure to coal dust -- is concentrated in the central Appalachian region of southern West Virginia, eastern Kentucky, and western Virginia.

“The cause of this resurgence in disease is likely multifactorial,” according to the bulletin. “Possible expla­nations include excessive exposure due to increases in coal mine dust levels and duration of exposure (longer working hours), and increases in crystalline silica exposure (see below). As indicated by data on disease prevalence and severity, workers in smaller mines may be at special risk.”

Bulletin #64 concludes that NIOSH’s earlier recommendations concerning the prevention of occupational respiratory disease among coal miners “remains essentially unaffected” by findings that have emerged since the publication of the 1995 document entitled,Criteria for a Recommended Standard—Occupational Exposure to Respirable Coal Mine Dust.

“While findings published since 1995 refine or add further to the understand­ing of the respiratory health effects of coal mine dust described in the NIOSH CCD, they do not contradict or critically modify the primary conclusions and associated recommendations given there. Rather, the new findings strength­en those conclusions and recommendations.”

The authors of the bulletin said that, as in the past, “every effort needs to be made to reduce exposure to both coal mine dust and to crystalline silica dust.” In order to accomplish that goal, they recommended establishing a separate compliance standard in order to provide an effective limit to exposure to crystalline silica dust.

The guidelines for acceptable exposure limits remain:
  • Exposures to respirable coal mine dust should be limited to 1 mg/m3 as a time-weighted average concentration for up to a 10 hour day during a 40 hour work week;
  • Exposures to respirable crystalline silica should be limited to 0.05 mg/m3 as a time-weighted average concentration for up to a 10 hour day during a 40 hour work week;
  • The periodic medical examination for coal miners should include spirometry;
  • Periodic medical examinations should include a standardized respiratory symptom questionnaire;
  • Surface coal miners should be added to and included in the periodic medical monitoring.