Mining Topic: Respiratory Diseases

What is the health and safety problem?

Miners are at risk of developing lung diseases called pneumoconioses because of their regular exposure to airborne dust, and miners who are exposed to exhaust from diesel engines have an increased risk of dying from lung cancer.

The two main pneumoconioses (meaning dusty lung) that affect miners are:

• coal workers’ pneumoconiosis (CWP) commonly called black lung; and
• silicosis.

CWP is associated with coal mining, but silicosis can affect workers in many types of mines and quarries, including coal mines.

Other respiratory diseases, such as chronic obstructive pulmonary disease (COPD), may also occur in miners separately from, or in addition to pneumoconiosis.

Exhaust from diesel engines has the potential to produce symptoms typical of asthma, and diesel exhaust exposure may contribute to other respiratory symptoms such as increased cough and phlegm. Additionally, miners with five or more years mining experience have an increased chance of dying from lung cancer.

What is the extent of the problem?

In 2010, CWP was the cause or a contributing factor in the death of 486 people. More than $45 billion dollars in federal compensation benefits have been paid to miners with CWP since 1968.

After a long period of decline, an increase in CWP has recently been seen in some areas of the country. A nationwide pneumoconiosis surveillance program administered by the National Institute for Occupational Safety and Health’s (NIOSH) Respiratory Health Division identified CWP in 2% of underground coal miners examined during 2007-2011. A newly published report shows that 2% of examined surface coal mine workers—most of whom had never worked in underground mines—had CWP.

The recently published Diesel Exhaust in Miners Study of over 12,000 miners showed a significant increased risk of dying from lung cancer among miners who had ever worked underground. This risk increased as the miners’ exposure to respirable elemental carbon – representing diesel exhaust – increased.

How is the NIOSH Mining program addressing this problem?

OMSHR (the NIOSH Office of Mine Safety and Health Research) conducts research to identify sources of respirable dust and diesel exhaust exposure in mining, and develops exposure control technologies.

Reducing miners’ exposure to airborne dust directly reduces their risk of developing dust-related respiratory disease.

OMSHR has active programs working to reduce dust exposure to coal miners operating longwall and continuous mining equipment. OMSHR is also investigating how to reduce dust exposure to miners in all commodities who are mobile workers (they don’t have a fixed work position), or who perform work:

• with exploratory and blasthole drills,
• with other surface mining equipment,
• with mills and processing equipment, or
• in operating cabs and rooms.

OMSHR is also assessing the application and performance of engineering controls to reduce diesel exhaust ‘at the tail pipe’ and in areas where miners perform their work.

Finally, OMSHR is continuing work to develop and improve monitors that will provide on-shift information about concentrations of airborne agents so that operators and miners can take steps to quickly correct conditions that could lead to excessive exposures. A summary of OMSHR’s current efforts related to monitoring exposure to dust and toxic substances can be found at: http://www.cdc.gov/niosh/mining/topics/monitoringdust.html.

What are the significant findings?

OMSHR has published resources for the mining industry to assist their effort to control dust and diesel exposure. These include Best Practices for Dust Control in Coal Mining, Best Practices for Dust Control in Metal/Nonmetal Mining, Dust Control Handbook for Industrial Minerals Mining and Processing, and Diesel Aerosols and Gases in Underground Mines: Guide to Exposure Assessment and Control.

OMSHR research has produced a continuous personal dust monitor that can provide an accurate measurement of airborne respirable dust at the end of a mine workers’ work shift, and provides on-shift information that the worker can use to reduce his or her exposure. This instrument has been approved for use as a coal mine dust personal sampler. Recent MSHA rulemaking specifies this instrument be used to measure dust exposure in certain coal mining operations.

OMSHR has also developed a mobile video exposure monitoring method and software application (Helmet-Cam) that combines real-time exposure data with concurrently recorded point-of-view video to identify exposure sources for mobile workers.

Factors affecting the protection from airborne dust by enclosed equipment operator cabs have been identified by OMSHR researchers, and a method to quantify air leakage into cabs has been published.

An instrument to monitor personal exposure to diesel exhaust particulate has been developed and demonstrated by OMSHR researchers. This instrument is commercially available.

What are the next steps?

OMSHR is currently evaluating potential dust control technologies such as tailgate spray manifolds on the longwall shearer, improved water sprays on longwall shields, stand-alone dust collectors on continuous mining sections, maintaining the dust control effectiveness of equipment cabs, and the application of optical remote sensing technology to monitor the source and movement of dust over extended areas.

OMSHR has also undertaken development of a methodology that would provide information about a worker’s exposure to respirable silica (quartz) at the end of the work shift. If this approach is validated, the delay in receipt of laboratory results would be eliminated. Removing this delay would allow the employer to more rapidly implement enhanced exposure controls, reducing the risk of silicosis among the exposed miners. 

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