As per a recent study by the National Institute for Occupational Safety and Health (NIOSH), exposure to coal dust can increase the severity of emphysema in both smokers and non-smokers.
The findings of the study highlight a health problem related to a growing industry, as coal production has nearly doubled worldwide in the past 25 years.
"In this study we have shown that coal mine dust exposure is a significant predictor of emphysema severity," said Dr. Eileen Kuempel, a senior scientist at NIOSH and lead author of the study.
The researchers compared lung autopsy results from 722 individuals, including 616 coal miners from West Virginia and 106 non-miners from West Virginia and Vermont.
In addition, age at death, race, miner/non-miner status and smoking history were established where possible, and individual exposure to coal dust was estimated using work history data and job-specific dust exposure estimates.
They then examined sections of the lungs to determine the presence and extent of emphysema.
A smaller subset of the study group had their lung tissue analysed for dust content. Emphysema was graded for type and severity.
The findings revealed that cumulative exposure to respirable coalmine dust was a highly significant predictor of emphysema severity after accounting for cigarette smoking, age at death, and race.
The researchers observed that miners tended to be older at death than non-miners due to a higher proportion of accidental or other sudden deaths among the non-miners.
Miners also smoked less on average, though differences were non significant.
However, emphysema in miners was significantly more severe than in non-miners among both smokers and never-smokers.
And predictably emphysema was also more severe among smokers than never smokers in both miners and non-miners.
Coal mine dust exposure and cigarette smoking had similar, additive effects on emphysema severity in this study.
The lung tissue analysis supported the findings- the greater the concentration of coaldust in the lungs, the more severe the emphysema.
The study has been published in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine (AJRCCM).